Επιστημονικές Δημοσιεύσεις

Heat stress decreases human physical work capacity (PWC), but the extent to which solar radiation (SOLAR) compounds this response is not well understood. This study empirically quantified how SOLAR impacts PWC in the heat, considering wide, but controlled, variations in air temperature, humidity, and clothing coverage. We also provide correction equations so PWC can be quantified outdoors using heat stress indices that do not ordinarily account for SOLAR (including the Heat Stress Index, Humidex, and Wet-Bulb Temperature). Fourteen young adult males (7 donning a work coverall, 7 with shorts and trainers) walked for 1 h at a fixed heart rate of 130 beats∙min-1, in seven combinations of air temperature (25 to 45°C) and relative humidity (20 or 80%), with and without SOLAR (800 W/m2 from solar lamps). Cumulative energy expenditure in the heat, relative to the work achieved in a cool reference condition, was used to determine PWC%. Skin temperature was the primary determinant of PWC in the heat. In dry climates with exposed skin (0.3 Clo), SOLAR caused PWC to decrease exponentially with rising air temperature, whereas work coveralls (0.9 Clo) negated this effect. In humid conditions, the SOLAR-induced reduction in PWC was consistent and linear across all levels of air temperature and clothing conditions. Wet-Bulb Globe Temperature and the Universal Thermal Climate Index represented SOLAR correctly and did not require a correction factor. For the Heat Stress Index, Humidex, and Wet-Bulb Temperature, correction factors are provided enabling forecasting of heat effects on work productivity.

Introduction: This study evaluated how single or combinations of weather parameters (temperature, humidity, wind speed, solar load) affect peak performance during endurance running events and identify which events are most vulnerable to varying weather conditions.

Methods: Results for the marathon, 50 km race-walk, 20 km race-walk, 10,000 m, 5,000 m and 3,000 m-steeplechase were obtained from the official websites of large competitions. We identified meteorological data from nearby (8.9 ± 9.3 km) weather stations for 1258 races held between 1936 and 2019 across 42 countries, enabling analysis of 7867 athletes.

Results: The Wet-Bulb Globe Temperature (WBGT) across races ranged from -7 to 33 °C, with 27% of races taking place in cold/cool, 47% in neutral, 18% in moderate heat, 7% in high heat, and 1% in extreme heat conditions, according to the World Athletics classification. Machine learning decision trees (R2 values: 0.21-0.58) showed that air temperature (importance score: 40%) was the most important weather parameter. But, when used alone, air temperature had lower predictive power (R2 values: 0.04-0.34) than WBGT (R2 values: 0.11-0.47). Conditions of 7.5-15 °C WBGT (or 10-17.5 °C air temperature) increase the likelihood for peak performance. For every degree WBGT outside these optimum conditions, performance declined by 0.3-0.4%.

Conclusion: More than one-quarter of endurance running events were held in moderate, high, or extreme heat and this number reaches one-half for events other than the marathon. All four weather parameters must be evaluated to mitigate the health and performance implications of exercising at maximal intensities in a hot environment with athletes adopting heat mitigation strategies when possible.

Extreme heat undermines the working capacity of individuals, resulting in lower productivity, and thus economic output. Here we analyse the present and future economic damages due to reduced labour productivity caused by extreme heat in Europe. For the analysis of current impacts, we focused on heatwaves occurring in four recent anomalously hot years (2003, 2010, 2015, and 2018) and compared our findings to the historical period 1981-2010. In the selected years, the total estimated damages attributed to heatwaves amounted to 0.3-0.5% of European gross domestic product (GDP). However, the identified losses were largely heterogeneous across space, consistently showing GDP impacts beyond 1% in more vulnerable regions. Future projections indicate that by 2060 impacts might increase in Europe by a factor of almost five compared to the historical period 1981-2010 if no further mitigation or adaptation actions are taken, suggesting the presence of more pronounced effects in the regions where these damages are already acute.

Ambient temperature can affect the survival rate of humans. Studies have shown a relationship between ambient temperature and mortality rate in hot and cold environments. This effect of ambient temperature on mortality seems to be more pronounced in older people. The aim of this study is to examine the effects of thermal stress on cardiovascular mortality and the associated relative risk per degree Celsius in Greek individuals ≥70 years old. Mortality data 1999-2012 were matched with the midday temperature. The present study found a higher circulatory mortality when ambient temperature is below or above the temperature range 6 to 39 °C.

Rising environmental temperatures have become a growing challenge for societies across the globe. At the same time, occupational heat strain undermines the health and productivity of individuals working in key industries. In this chapter, we combine a narrative review with observational studies to outline the 18 factors affecting the risk for experiencing heat strain during work and leisure, which are: acclimatization, aging, anthropometrics, clothing, cultural habits, diet, disabilities, drugs and addictions, environmental stress, ethnicity, heat mitigation, medical conditions, metabolic demands, physical fitness, sex, sleep deprivation, work duration, and work experience. Addressing these risk factors will generate significant savings to healthcare systems from the occupational heat illness, absenteeism, and mortality associated with heat strain. Increased efforts should be made to educate individuals and organizations about the health, performance, and productivity risks related to heat strain and appropriate screening protocols should be incorporated within health and safety legislation.

Governments, international sports bodies, and industry must take responsibility for barriers to health experienced by migrant workers involved in events such as the Olympic Games and FIFA World Cup, argue Kristine Husøy Onarheim and colleagues.

Data suggest migrant construction workers are at risk of work related ill health, injury, and death, but better evidence to inform policy making and improve their health is needed, say Andreas Flouris and colleagues.

Background: The European Union Directives stipulate mandatory tests for the presence of any infections in donors and donations of substances of human origin (SoHO). In some circumstances, other pathogens, including fungi and parasites, may also pose a threat to the microbial safety of SoHO.

Objective: The aim of the two systematic reviews is to identify, collect, and evaluate scientific evidence for the presence of fungal and parasitic infections in donors and donations of SoHO, and their transmission via transfusion and transplantation.

Methods: An algorithmic search, one each for fungal and parasitic disease, was applied to 6 scientific databases (PubMed, EMBASE, Web of Science, Scopus, Cochrane Library [trials], and CINAHL). Additionally, manual and algorithmic searches were employed in 15 gray literature databases and 22 scientific organization websites. The criteria for eligibility included peer-reviewed publications and peer-reviewed abstract publications from conference proceedings examining the prevalence, incidence, odds ratios, risk ratios, and risk differences for the presence of fungi and parasites in donors and SoHO donations, and their transmission to recipients. Only studies that scrutinized the donors and donations of human blood, blood components, tissues, cells, and organs were considered eligible. Data extraction from eligible publications will be performed independently by two reviewers. Data synthesis will include a qualitative description of the studies lacking evidence suitable for a meta-analysis and a random or fixed-effect meta-analysis model for quantitative data synthesis.

Results: This is an ongoing study. The systematic reviews are funded by the European Centre for Disease Prevention and Control, and the results are expected to be presented by the end of 2021.

Conclusions: The systematic reviews will provide the basis for developing a risk assessment for fungal and parasitic disease transmission via SoHO.

Background: Occupational heat exposure can provoke health problems that increase the risk of certain diseases and affect workers’ ability to maintain healthy and productive lives. This study investigates the effects of occupational heat stress on workers’ physiological strain and labor productivity, as well as examining multiple interventions to mitigate the problem.

Methods: We monitored 518 full work-shifts obtained from 238 experienced and acclimatized individuals who work in key industrial sectors located in Cyprus, Greece, Qatar, and Spain. Continuous core body temperature, mean skin temperature, heart rate, and labor productivity were collected from the beginning to the end of all work-shifts.

Results: In workplaces where self-pacing is not feasible or very limited, we found that occupational heat stress is associated with the heat strain experienced by workers. Strategies focusing on hydration, work-rest cycles, and ventilated clothing were able to mitigate the physiological heat strain experienced by workers. Increasing mechanization enhanced labor productivity without increasing workers’ physiological strain.

Conclusions: Empowering laborers to self-pace is the basis of heat mitigation, while tailored strategies focusing on hydration, work-rest cycles, ventilated garments, and mechanization can further reduce the physiological heat strain experienced by workers under certain conditions.

Objectives: To derive an empirical model for the impact of aerobic fitness (maximal oxygen consumption; V̇O2max in mL∙kg-1∙min-1) on physical work capacity (PWC) in the heat.

Design: Prospective, repeated measures.

Methods: Total work completed during 1 h of treadmill walking at a fixed heart rate of 130 b∙min-1 was assessed in 19 young adult males across a variety of warm and hot climate types, characterised by wet-bulb globe temperatures (WBGT) ranging from 12 to 40 °C. For data presentation and obtaining initial parameter estimates for modelling, participants were grouped into low (n = 6, 74 trials), moderate (n = 8, 76 trials), and high (n = 5, 29 trials) fitness, with group mean V̇O2max 42, 52, and 64 mL∙kg-1∙min-1, respectively. For the heated conditions (WBGT 18 to 40 °C), we calculated PWC% by expressing total energy expenditure (kJ above resting) in each trial relative to that achieved in a cool reference condition (WBGT = 12 °C = 100% PWC).

Results: The relative reduction in energy expenditure (PWC%) caused by heat was significantly smaller by up to 16% for the fit participants compared to those with lower aerobic capacity. V̇O2max also modulated the relationship between sweat rate and body temperature changes to increasing WBGT. Including individual V̇O2max data in the PWC prediction model increased the predicting power by 4%.

Conclusions: Incorporating individual V̇O2max improved the predictive power of the heat stress index WBGT for Physical Work Capacity in the heat. The largest impact of V̇O2max on PWC was observed at a WBGT between 25 and 35 °C.

Purpose: We investigated the environmental conditions in which all outdoor International Tennis Federation (ITF) junior tournaments (athlete ages: <18 y) were held during 2010-2019. Thereafter, we performed a crossover trial (ClinicalTrials.gov: NCT04197375) assessing the efficacy of head-neck precooling for mitigating the heat-induced psychophysical and performance impacts on junior athletes during tennis match play. Methods: ITF junior tournament information was collected. We identified meteorological data from nearby (13.6 [20.3] km) weather stations for 3056 (76%) tournaments. Results: Overall, 30.1% of tournaments were held in hot (25°C-30°C wet-bulb globe temperature [WBGT]; 25.9%), very hot (30°C-35°C WBGT; 4.1%), or extremely hot (>35°C WBGT; 0.1%) conditions. Thereafter, 8 acclimatized male junior tennis athletes (age = 16.0 [0.9] y; height = 1.82 [0.04] m; weight = 71.3 [11.1] kg) were evaluated during 2 matches: one with head-neck precooling (27.7°C [2.2°C] WBGT) and one without (27.9°C [1.8°C] WBGT). Head-neck precooling reduced athletes’ core temperature from 36.9°C (0.2°C) to 36.4°C (0.2°C) (P = .001; d = 2.4), an effect reduced by warm-up. Head-neck precooling reduced skin temperature (by 0.3°C [1.3°C]) for the majority of the match and led to improved (P < .05) perceived exertion (by 13%), thermal comfort (by 14%), and thermal sensation (by 15%). Muscle temperature, heart rate, body weight, and urine specific gravity remained unaffected (P ≥ .05; d < 0.2). Small or moderate improvements were observed in most performance parameters assessed (d = 0.20-0.79).

Conclusions: Thirty percent of the last decade’s ITF junior tournaments were held in hot, very hot, or extremely hot conditions (25°C-36°C WBGT). In such conditions, head-neck precooling may somewhat lessen the physiological and perceptual heat strain and lead to small to moderate improvements in the match-play performance of adolescent athletes.

Background: The aim of the study was to investigate the effect of a simulated heat-wave on the labour productivity and physiological strain experienced by workers.

Methods: Seven males were confined for ten days in controlled ambient conditions. A familiarisation day was followed by three (pre, during, and post-heat-wave) 3-day periods. During each day volunteers participated in a simulated work-shift incorporating two physical activity sessions each followed by a session of assembly line task. Conditions were hot (work: 35.4 °C; rest: 26.3 °C) during, and temperate (work: 25.4 °C; rest: 22.3 °C) pre and post the simulated heat-wave. Physiological, biological, behavioural, and subjective data were collected throughout the study.

Results: The simulated heat-wave undermined human capacity for work by increasing the number of mistakes committed, time spent on unplanned breaks, and the physiological strain experienced by the participants. Early adaptations were able to mitigate the observed implications on the second and third days of the heat-wave, as well as impacting positively on the post-heat-wave period.

Conclusions: Here, we show for first time that a controlled simulated heat-wave increases workers’ physiological strain and reduces labour productivity on the first day, but it promotes adaptations mitigating the observed implications during the subsequent days.

Objectives: To provide perspectives from the HEAT-SHIELD project (www.heat-shield.eu): a multi-national, inter-sectoral, and cross-disciplinary initiative, incorporating twenty European research institutions, as well as occupational health and industrial partners, on solutions to combat negative health and productivity effects caused by working on a warmer world.

Methods: In this invited review, we focus on the theoretical and methodological advancements developed to combat occupational heat stress during the last five years of operation.

Results: We outline how we created climate forecast models to incorporate humidity, wind and solar radiation to the traditional temperature-based climate projections, providing the basis for timely, policy-relevant, industry-specific and individualized information. Further, we summarise the industry-specific guidelines we developed regarding technical and biophysical cooling solutions considering effectiveness, cost, sustainability, and the practical implementation potential in outdoor and indoor settings, in addition to field-testing of selected solutions with time-motion analyses and biophysical evaluations. All recommendations were adjusted following feedback from workshops with employers, employees, safety officers, and adjacent stakeholders such as local or national health policy makers. The cross-scientific approach was also used for providing policy-relevant information based on socioeconomic analyses and identification of vulnerable regions considered to be more relevant for political actions than average continental recommendations and interventions.

Discussion: From the HEAT-SHIELD experiences developed within European settings, we discuss how this inter-sectoral approach may be adopted or translated into actionable knowledge across continents where workers and societies are affected by escalating environmental temperatures.

Escalating environmental temperatures are expected to influence performance and planning of several future football events, for example, FIFA World Cups, regular league and continental cup matches and climate projections for Tokyo (Olympic Games postponed to August 2021) implies that athletes are facing high heat exposure in the next Olympic football tournament. Prompted by global warming, but also with current conditions and historic heat-events in mind, it is relevant to consider the consequences for football play and players health. Heat stress has detrimental effects on endurance performances and sudden or extreme exposure is a major health concern. Moreover, heat stress could, in some situations, create an unsportsmanlike competitive advantage for the home team and fair play may require special planning and precaution procedures.

Successful implementation of cooling strategies obviously depends on identifying effective interventions, but in industrial settings, it is equally important to consider feasibility and economic viability. Many cooling interventions are available, but the decision processes affecting adoption by end-users are not well elucidated. We therefore arranged two series of meetings with stakeholders to identify knowledge gaps, receive feedback on proposed cooling interventions, and discuss factors affecting implementation of heat-health interventions. This included four meetings attended by employers, employees, and health and safety officers (n = 41), and three meetings attended primarily by policy makers (n = 74), with feedback obtained via qualitative and quantitative questionnaires and focus group discussions. On a 10-point scale, both employers and employees valued worker safety (9.1 ± 1.8; mean±SD) and health (8.5 ± 1.9) as more important than protecting company profits (6.3 ± 2.3). Of the respondents, 41% were unaware of any cooling strategies at their company and of those who were aware, only 30% thought the interventions were effective. Following presentation of proposed interventions, the respondents rated “facilitated hydration”, “optimization of clothing/protective equipment”, and “rescheduling of work tasks” as the top-three preferred solutions. The main barriers for adopting cooling interventions were cost, feasibility, employer perceptions, and legislation. In conclusion, preventing negative health and safety effects was deemed to be more important than preventing productivity loss. Regardless of work sector or occupation, both health and wealth were emphasized as important parameters and considered as somewhat interrelated. However, a large fraction of the European worker force lacks information on effective measures to mitigate occupational heat stress. List of abbreviations: OH-Stress: Occupational heat stress; WBGT: Wet Bulb Globe Temperature.

Background: Within the context of the COVID-19 pandemic, the WHO endorses facemask use to limit aerosol-spreading of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, concerns have been raised regarding facemask-associated dyspnea, thermal distress and self-reported impairment of cognition. Accordingly, we tested how facemask-use affects motor-cognitive performances of relevance for occupational safety. We hypothesized that mask use would affect cognitively dominated performances and thermal discomfort, but not alter whole-body thermal balance. Methods: Eight participants completed a facemask and a barefaced (control) trial, in a counterbalanced order, in 40°C and 20% humidity conditions. Motor-cognitive performance, physiological (rectal, mean skin and local facial temperatures) and perceptual (thermal comfort and dyspnea) measures were assessed at baseline and following 45 min of light work (100 W). Results: Perceived dyspnea was aggravated with prolonged facemask use (p = 0.04), resulting in 36% greater breathlessness compared to control. However, no other differences were observed in motor-cognitive performance, physiological strain, or thermal discomfort. Conclusions: Contradicting negative self-reported impacts of facemask-use, only dyspnea was aggravated in the present study, thereby reinforcing global recommendations of mask use, even in hot environments. (Funded by: European Union’s Horizon 2020 research and innovation program under the grant agreement No 668786).

New findings: What is the central question of this study? Repeated heat exposure during the summer months can enhance heat loss in humans (seasonal heat acclimatisation), but does the magnitude of that enhancement differ between young and older adults when assessed during passive heat exposure? What is the main finding and its importance? While seasonal heat acclimatisation enhanced evaporative heat loss (i.e. sweating) in both young and older adults, those improvements led to a greater reduction in body heat storage in older adults. These outcomes indicate that heat acclimatisation may confer greater thermoregulatory benefits with increasing age.

Abstract: Repeated heat exposure throughout summer can enhance heat loss in humans (seasonal heat acclimatisation), although the effect of ageing on those improvements remains unclear. We therefore sought to assess thermoregulatory function in young and older adults during environmental heat exposure prior to and following seasonal heat acclimatisation, hypothesizing that the magnitude of adaptation would be greater in older relative to young adults. To achieve this, 14 young (19-27 years) and 10 older adults (55-72 years), who resided in a temperate humid-continental climate, completed a 3 h resting heat exposure (44°C, ∼30% relative humidity) in the winter-spring months as part of a larger investigation (pre-acclimatisation), before being re-evaluated using the same heat stress test following the summer months (post-acclimatisation). Whole-body dry and evaporative heat exchange, and metabolic rate were measured throughout using direct and indirect calorimetry (respectively), and used to quantify body heat storage (metabolic rate + dry heat gain – evaporative heat loss). Evaporative heat loss increased in both groups following acclimatisation, but those improvements led to a decrease in body heat storage in older (mean difference (95% CI); 213 (295, 131) kJ; P < 0.001), but not young adults (-25 (-94, 44) kJ; P = 0.458). Thus, body heat storage was greater in older compared to young adults before (222 (123, 314) kJ; P < 0.001), but not following acclimatisation (34 (-55, 123) kJ; P = 0.433). Although there is a need for larger and more controlled confirmatory studies, our findings indicate that seasonal heat acclimatisation may induce greater thermoregulatory adaptation in older compared to young adults.

Health and performance impairments provoked by thermal stress are societal challenges geographically spreading and intensifying with global warming. Yet, science may be underestimating the true impact, since no study has evaluated effects of sunlight exposure on human brain temperature and function. Accordingly, performance in cognitively dominated and combined motor-cognitive tasks and markers of rising brainstem temperature were evaluated during exposure to simulated sunlight (equal to ~1000 watt/m2). Acute exposure did not affect any performance measures, whereas prolonged exposure of the head and neck provoked an elevation of the core temperature by 1 °C and significant impairments of cognitively dominated and motor task performances. Importantly, impairments emerged at considerably lower hyperthermia levels compared to previous experiments and to the trials in the presents study without radiant heating of the head. These findings highlight the importance of including the effect of sunlight radiative heating of the head and neck in future scientific evaluations of environmental heat stress impacts and specific protection of the head to minimize detrimental effects.

White adipose tissue (WAT) thermogenic activity may play a role in whole-body energy balance and two of its main regulators are thought to be environmental temperature (Tenv) and exercise. Low Tenv may increase uncoupling protein one (UCP1; the main biomarker of thermogenic activity) in WAT to regulate body temperature. On the other hand, exercise may stimulate UCP1 in WAT, which is thought to alter body weight regulation. However, our understanding of the roles (if any) of Tenv and exercise in WAT thermogenic activity remains incomplete. Our aim was to examine the impacts of low Tenv and exercise on WAT thermogenic activity, which may alter energy homeostasis and body weight regulation. We conducted a series of four experimental studies, supported by two systematic reviews and meta-analyses. We found increased UCP1 mRNA (p = 0.03; but not protein level) in human WAT biopsy samples collected during the cold part of the year, a finding supported by a systematic review and meta-analysis (PROSPERO review protocol: CRD42019120116). Additional clinical trials (NCT04037371; NCT04037410) using Positron Emission Tomography/Computed Tomography (PET/CT) revealed no impact of low Tenv on human WAT thermogenic activity (p > 0.05). Furthermore, we found no effects of exercise on UCP1 mRNA or protein levels (p > 0.05) in WAT biopsy samples from a human randomized controlled trial (Clinical trial: NCT04039685), a finding supported by systematic review and meta-analytic data (PROSPERO review protocol: CRD42019120213). Taken together, the present experimental and meta-analytic findings of UCP1 and SUVmax, demonstrate that cold and exercise may play insignificant roles in human WAT thermogenic activity.

Aging exacerbates hyperthermia and cardiovascular strain during passive heat exposure, but it remains unclear whether those effects worsen in older adults with type 2 diabetes (T2D). We examined these responses in unacclimatized, physically active, older individuals with (n = 13, mean ± SD age: 60 ± 8 years, HbA1c: 7.0 ± 1.0%) and without (Control, n = 30, 62 ± 6 years) well-controlled T2D during a brief, 3-h passive exposure to extreme heat (44°C, 30% relative humidity). Metabolic heat production, dry heat gain, total heat gain (metabolic heat production + dry heat gain), evaporative heat loss, body heat storage (summation of heat gain/loss), rectal and mean skin temperatures as well as heart rate were measured continuously. No between-group differences were observed for metabolic heat production (T2D vs. Control; 53 ± 5 vs. 55 ± 7 W/m2), dry heat gain (48 ± 9 vs. 47 ± 11 W/m2), total heat gain (101 ± 10 vs. 102 ± 14 W/m2) and evaporative heat loss (83 ± 10 vs. 85 ± 12 W/m2) over the 3 h (all P > 0.05). Consequently, the changes in body heat storage (380 ± 93 vs. 358 ± 172 kJ, P = 0.67) were similar between groups. Moreover, no between-group differences in rectal and mean skin temperatures or heart rate were measured. We conclude that unacclimatized, physically active, older adults with well-controlled T2D do not experience greater hyperthermia and cardiovascular strain compared to their healthy counterparts while resting in extreme heat for a brief, 3-h period.

Heat exposure constitutes a major threat for European workers, with significant impacts on the workers’ health and productivity. Climate projections over the next decades show a continuous and accelerated warming over Europe together with longer, more intense and more frequent heatwaves on regional and local scales. In this work, we assess the increased risk in future occupational heat stress levels using the wet bulb globe temperature (WBGT), an index adopted by the International Standards Organization as regulatory index to measure the heat exposure of working people. Our results show that, in large parts of Europe, future heat exposure will indeed exceed critical levels for physically active humans far more often than in today’s climate, and labour productivity might be largely reduced in southern Europe. European industries should adapt to the projected changes to prevent major consequences for the workers’ health and to preserve economic productivity.

Purpose: This study aimed to detect potential differences in heart-rate variability (HRV) during a moderate-intensity intermittent exercise in the heat among physically active young (25.8 ± 1.9 years), middle-aged (43.5 ± 2.8 years), and older (62.9 ± 3.7 years) men.

Methods: Thirty-three participants (11/group) performed four successive bouts of 15-min cycling at a moderate fixed rate of metabolic heat production of ~ 400 W; each separated by a 15-min recovery with 1 h of final recovery in a hot and dry environment (35 °C, 20% relative humidity). Twelve HRV indices were computed that have been commonly described in the literature, and characterized various domains of the variability and complexity of heart rate.

Results: Cardiac autonomic regulation during intermittent exercise in the heat, as well as during pre-exercise rest and recovery was significantly affected by age, as changes were observed among the three different aged groups in five indices (p ≤ 0.05). Similarly, time influenced cardiac autonomic regulation as three indices showed changes across time (p ≤ 0.05) during intermittent exercise, whilst five indices displayed significant changes (p ≤ 0.05) during rest and recovery in the heat.

Conclusions: This study supports that moderate-intensity intermittent exercise in the heat is associated with significant cardiac autonomic dysregulation in older men, as compared to young and middle-aged men, yet it highlights the importance of developing preventative health strategies for heat-related illness in aged individuals.

The frequency of extreme heat events, such as the summer of 2003 in Europe, and their corresponding consequences for human beings are expected to increase under a warmer climate. The joint collaboration of institutional agencies and multidisciplinary approaches is essential for a successful development of heat-health warning systems and action plans which can reduce the impacts of extreme heat on the population. The present work constitutes a state-of-the-art review of 16 European heat-health warning systems and heat-health action plans, based on the existing literature, web search (over the National Meteorological Services websites) and questionnaires. The aim of this study is to pave the way for future heat-health warning systems, such as the one currently under development in the framework of the Horizon 2020 HEAT-SHIELD project. Some aspects are highlighted among the variety of examined European warning systems. The meteorological variables that trigger the warnings should present a clear link with the impact under consideration and should be chosen depending on the purpose and target of the warnings. Setting long-term planning actions as well as pre-alert levels might prevent and reduce damages due to heat. Finally, education and communication are key elements of the success of a warning system.

Heat stress is a deadly occupational hazard that is projected to increase in severity with global warming. While upper limits for heat stress designed to protect all workers have been recommended by occupational safety institutes for some time, heat stress continues to compromise health and productivity. In our view, this is largely explained by the inability of existing guidelines to consider the inter-individual (age, sex, disease, others) and intra-individual (medication use, fitness, hydration, others) factors that cause extensive variability in physiological tolerance to a given heat stress. In conditions that do not exceed the recommended limits, this ‘one size fits all’ approach to heat stress management can lead to reductions in productivity in more heat-tolerant workers, while compromising safety in less heat-tolerant workers who may develop heat-related illness, even in temperate conditions. Herein, we discuss future directions in occupational heat stress management that consider this individual variability.

We conducted a secondary analysis to investigate whether age-related attenuations in heart rate variability (HRV) worsen during exposure to moderate, dry (36.5°C, 20% RH) or humid (36.5°C, 60% RH) heat conditions that resulted in greater body heat storage among older compared to young participants, and during humid compared to dry heat, regardless of age. Six HRV indices [heart rate (HR), coefficient of variation (CoV), detrended fluctuation analysis: α1, low frequency power, high frequency power, and low/high frequency ratio] were assessed in 10 young (21 ± 3 y) and 9 older (65 ± 5 y) adults for 15-min prior to (baseline), and at the end of a 120-min exposure to dry and humid heat while seated at rest. Our results demonstrated a condition (dry and humid) x time (baseline and end) interaction effect on HR (p = 0.047) such that HR gradually increased during humid heat exposure yet remained similar during dry heat exposure across groups. We also found an age-related attenuation in CoV at baseline for both the dry (young: 0.097 ± 0.023%; older: 0.054 ± 0.016%) and humid (young: 0.093 ± 0.034%; older: 0.056 ± 0.014%) heat conditions (p < 0.02). Those age-related attenuations in CoV, however, were not magnified throughout the exposure nor different between conditions (p > 0.05). While older adults stored more heat during a brief 120-min exposure to dry heat compared to their young counterparts, this was not paralleled by further age-related impairments in HRV even when body heat storage and cardiovascular strain were exacerbated by exposure to humid heat.

This physiology study assesses whole-body heat loss in physically active middle-aged and older men with vs without type 2 diabetes after aerobic cycling to evaluate whether type 2 diabetes impairs heat loss and by what mechanism.

Performing exercise in the heat can increase the risk of health complications, especially among middle-aged and older adults who have impaired whole-body heat loss (WBHL) relative to young adults.1 That risk may be higher among patients with type 2 diabetes due to abnormalities in cutaneous vasodilation and sweating, which facilitate WBHL.2 However, repeated brief exercise for 7 days or more during heat exposure (heat acclimation) may mitigate this risk by enhancing WBHL.3 We therefore assessed whether type 2 diabetes impairs heat loss in physically active middle-aged and older adults during exercise heat stress and whether heat acclimation could offset any impairment.

Existing heat–health warning systems focus on warning vulnerable groups in order to reduce mortality. However, human health and performance are affected at much lower environmental heat strain levels than those directly associated with higher mortality. Moreover, workers are at elevated health risks when exposed to prolonged heat. This study describes the multilingual “HEAT-SHIELD occupational warning system” platform (https://heatshield.zonalab.it/) operating for Europe and developed within the framework of the HEAT-SHIELD project. This system is based on probabilistic medium-range forecasts calibrated on approximately 1800 meteorological stations in Europe and provides the ensemble forecast of the daily maximum heat stress. The platform provides a non-customized output represented by a map showing the weekly maximum probability of exceeding a specific heat stress condition, for each of the four upcoming weeks. Customized output allows the forecast of the personalized local heat-stress-risk based on workers’ physical, clothing and behavioral characteristics and the work environment (outdoors in the sun or shade), also taking into account heat acclimatization. Personal daily heat stress risk levels and behavioral suggestions (hydration and work breaks recommended) to be taken into consideration in the short term (5 days) are provided together with long-term heat risk forecasts (up to 46 days), all which are useful for planning work activities. The HEAT-SHIELD platform provides adaptation strategies for “managing” the impact of global warming.

Bicyclists can be subjected to crashes, which can cause injuries over the whole body, especially the head. Head injuries can be prevented by wearing bicycle helmets; however, bicycle helmets are frequently not worn due to a variety of reasons. One of the most common complaints about wearing bicycle helmets relates to thermal discomfort. So far, insufficient attention has been given to the thermal performance of helmets. This paper aimed to introduce and develop an adaptive model for the online monitoring of head thermal comfort based on easily measured variables, which can be measured continuously using impeded sensors in the helmet. During the course of this work, 22 participants in total were subjected to different levels of environmental conditions (air temperature, air velocity, mechanical work and helmet thermal resistance) to develop a general model to predict head thermal comfort. A reduced-order general linear regression model with three input variables, namely, temperature difference between ambient temperature and average under-helmet temperature, cyclist’s heart rate and the interaction between ambient temperature and helmet thermal resistance, was the most suitable to predict the cyclist’s head thermal comfort and showed maximum mean absolute percentage error (MAPE) of 8.4%. Based on the selected model variables, a smart helmet prototype (SmartHelmet) was developed using impeded sensing technology, which was used to validate the developed general model. Finally, we introduced a framework of calculation for an adaptive personalised model to predict head thermal comfort based on streaming data from the SmartHelmet prototype.

The assessment of energy cost (EC) at the workplace remains a key topic in occupational health due to the ever-increasing prevalence of work-related issues. This review provides a detailed list of EC estimations in jobs/tasks included in tourism, agriculture, construction, manufacturing, and transportation industries. A total of 61 studies evaluated the EC of 1,667 workers while performing a large number of tasks related to each of the aforementioned five industries. Agriculture includes the most energy-demanding jobs (males: 6.0 ± 2.5 kcal/min; females: 2.9 ± 1.0 kcal/min). Jobs in the construction industry were the 2nd most demanding (males: 4.9 ± 1.6 kcal/min; no data for females). The industry with the 3rd highest EC estimate was manufacturing (males: 3.8 ± 1.1 kcal/min; females: 3.0 ± 1.3 kcal/min). Transportation presented relatively moderate EC estimates (males: 3.1 ± 1.0 kcal/min; no data for females). Tourism jobs demonstrated the lowest EC values (2.5 ± 0.9 kcal/min for males and females). It is hoped that this information will aid the development of future instruments and guidelines aiming to protect workers’ health, safety, and productivity. Future research should provide updated EC estimates within a wide spectrum of occupational settings taking into account the sex, age, and physiological characteristics of the workers as well as the individual characteristics of each workplace.

Occupational heat strain is a public health threat, and for outdoor industries there is a direct influence from elevated environmental temperatures during heat waves. However, the impact in indoor settings is more complex as industrial heat production and building architecture become factors of importance. Therefore, this study evaluated effects of heat waves on manufacturing productivity. Production halls in a manufacturing company were instrumented with 33 dataloggers to track air temperature and humidity. In addition, outdoor thermal conditions collected from a weather station next to the factory and daily productivity evaluated as overall equipment efficiency (OEE) were obtained, with interaction between productivity and thermal conditions analyzed before, during, and after four documented heat waves (average daily air temperature above 24°C on at least three consecutive days). Outdoor (before: 21.3° ± 4.6°C, during: 25.5° ± 4.3°C, and after: 19.8° ± 3.8°C) and indoor air temperatures (before: 30.4° ± 1.3°C, during: 32.8° ± 1.4°C, and after: 30.1° ± 1.4°C) were significantly elevated during the heat waves (p < 0.05). OEE was not different during the heat waves when compared with control, pre-heat-wave, and post-heat-wave OEE. Reduced OEE was observed in 3-day periods following the second and fourth heat wave (p < 0.05). Indoor workers in settings with high industrial heat production are exposed to a significant thermal stress that may increase during heat waves, but the impact on productivity cannot be directly derived from outdoor factors. The significant decline in productivity immediately following two of the documented heat waves could relate to a cumulative effect of the thermal strain experienced during work combined with high heat stress in the recovery time between work shifts.

Numerous individual factors (e.g. fitness, sex, body morphology) are known to independently modulate heat exchange during exercise in the heat. However, in our view, the individual factor(s) making the greatest contribution to the variation in heat exchange among men and women remains poorly understood, despite several studies. We therefore sought to revisit this question by assessing whole-body dry and evaporative heat exchange using direct calorimetry in a heterogeneous sample of 100 young men (= 57) and women (= 43). Participants performed three 30 min bouts of cycling at very light (men/women; 300/250 W), light (400/325 W) and moderate (500/400 W) metabolic heat production rates, separated by a 15 min recovery, in dry heat (40°C, ∼12% relative humidity). Positive associations were observed between the evaporative heat loss requirement (metabolic heat production ± dry heat exchange) and evaporative heat loss (all < 0.01), especially during moderate exercise (men, = 0.62; women, = 0.82), which explained 19–67% of individual variation. Peak aerobic power (in millilitres per kilogram per minute) was also positively related to evaporative heat loss in both sexes, albeit only during light and moderate exercise (= 0.33–0.43; all < 0.05), explaining a further 5–9% of individual variation. Dry heat exchange shared negative associations with body mass and surface area during all exercise bouts in both sexes (= −0.29 to −0.55; all < 0.05), explaining 9–30% of individual variation. We therefore demonstrate that the evaporative heat loss requirement, peak aerobic power and body morphology are the greatest contributors to the variation in whole-body heat exchange among young men and women exercising in dry heat, with the strength of those relationships being heat-load dependent.

New findings: What is the central question of this study? Does a delay in cold water immersion treatment affect the cardiac autonomic control of exertionally heat-strained individuals? What is the main finding and its importance? Cold water immersion is effective for treating exertionally heat-strained individuals even when treatment is commenced with a significant delay. However, that treatment delay leads to only partial/transient restoration of cardiac autonomic control. Therefore, we recommend that exertional heatstroke patients are continuously monitored for several hours even after core temperature has returned to normal values.

Abstract: Immediate cold water immersion (CWI) is the gold-standard treatment for exertional heatstroke. In the field, however, treatment is often delayed, primarily owing to a delayed paramedic response and/or inaccurate diagnosis. We examined the effect of treatment (reduction of rectal temperature to 37.5°C) delays of 5 (short), 20 (moderate) and 40 (prolonged) min on cardiac autonomic control [as assessed via heart rate variability (HRV)] in eight exertionally heat-strained (40.0°C rectal temperature) individuals. Eleven HRV indices were computed that have been described commonly in the literature and characterize almost all known domains of the variability and complexity of the cardiopulmonary system. We found that the cardiac autonomic control (as assessed via HRV) of exertionally heat-strained individuals was significantly affected by the amount of time it took for the CWI treatment to be applied. Six out of 11 HRV indices studied, from all variability domains, displayed strong (P ≤ 0.005) time × delay interaction effects. Moreover, the number of significantly (P ≤ 0.005) abnormal (i.e. different from the short delay) HRV indices more than doubled (seven versus 15) from the moderate delay to the prolonged delay. Finally, our results demonstrated that a CWI treatment applied with delays of 20 and, primarily, 40 min did not lead to a full restoration of cardiac autonomic control of exertionally heat-strained individuals. In conclusion, this study supports CWI for treating exertionally heat-strained individuals even when applied with prolonged delay, but it highlights the importance of continued cardiac monitoring of patients who have suffered exertional heatstroke for several hours after restoration of core temperature to normal.

Our primary objective in this study was to design and implement the FAME Lab PHS Calculator software (PHSFL) (www.famelab.gr/research/downloads), a free tool to calculate the predicted heat strain of an individual based on ISO 7933:2018. Our secondary objective was to optimize the practicality of the PHSFL by incorporating knowledge from other ISO standards and published literature. The third objective of this study was to assess: (i) the criterion-related validity of the PHSFL by comparing its results against those obtained using the original ISO 7933:2018 code; and (ii) the construct validity of the PHSFL by comparing its results against those obtained via field experiments performed in human participants during work in the heat. Our analysis for criterion validity demonstrates that PHSFL provides valid results within the required computational accuracy, according to Annex F of ISO 7933:2018. The construct validity showed that root mean square errors (RMSE) and 95% limits of agreement (LOA) were minimal between measured and predicted core temperature (RMSE: 0.3°C; LOA: 0.06 ± 0.58°C) and small between measured and predicted mean skin temperature (RMSE: 1.1°C; LOA: 0.59 ± 1.83°C). In conclusion, the PHSFL software demonstrated strong criterion-related and construct-related validity.

Less is known on bone mass gains in dancers involved in vocational dance training. The present study found that, as young vocational dancers progress on their professional training, their bone health remains consistently lower compared to non-exercising controls. Endocrine mechanisms do not seem to explain these findings.

Purpose: Little is known on bone mass development in dancers involved in vocational training. The aim of the present study was to model bone mineral content (BMC) accruals and to determine whether circulating levels of oestrogens, growth hormone (GH), and insulin-like growth factor I (IGF-1) explain differences in bone mass gains between vocational dance students and matched controls.

Methods: The total of 67 vocational female dancers (VFDs) and 68 aged-matched controls (12.1 ± 1.9 years and 12.7 ± 2.0 years at baseline, respectively) were followed for two consecutive years (34 VFD and 31 controls remained in the study for the full duration). BMC was evaluated annually at impact [femoral neck (FN); lumbar spine (LS)] and non-impact sites (forearm) using DXA. Anthropometry, age at menarche (questionnaire), and hormone serum concentrations (immunoradiometric assays) were also assessed for the same period.

Results: VFD demonstrated consistently reduced body weight (p < 0.001) and BMC at all three anatomical sites (p < 0.001) compared to controls throughout the study period. Menarche, body weight, GH, and IGF-1 were significantly associated with bone mass changes over time (p < 0.05) but did not explain group differences in BMC gains at impact sites (p > 0.05). However, body weight did explain the differences between groups in terms of BMC gains at the forearm (non-impact site).

Conclusion: Two consecutive years of vocational dance training revealed that young female dancers demonstrate consistently lower bone mass compared to controls at both impact and non-impact sites. The studied endocrine parameters do not seem to explain group differences in terms of bone mass gains at impact sites.

Changing patterns of heat waves are part of the global warming effect and the importance of changes is reinforced by their negative impact on society. Firstly, heat waves were analyzed in Brnik (Slovenia) and Larisa (Greece) in the period 1981⁻2017 to reflect the environment which workers are exposed to. Secondly, outdoor workers (70 from Greece, 216 from Slovenia) provided a self-assessment of heat stress. The heat wave timeline is presented as an effective way of illustrating long-term changes in heat waves’ characteristics for various stakeholders. In both countries, workers assessed as significant the heat stress impact on productivity (Greece 69%, Slovenia 71%; p > 0.05), and in Slovenia also on well-being (74%; p < 0.01). The main experienced symptoms and diseases were thirst (Greece 70%, Slovenia 82%; p = 0.03), excessive sweating (67%, 85%; p = 0.01), exhaustion (51%, 62%; p > 0.05) and headache (44%, 53%; p > 0.05). The most common way to reduce heat stress was drinking more water (Greece 64%, Slovenia 82%; p = 0.001). Among the informed workers, the prevalent source of information was discussions. Therefore, educational campaigns are recommended, together with the testing of the efficiency of mitigation measures that will be proposed on the Heat-Shield project portal.

Given the lack of relevant data, the aim of this study was to examine femur cortical and trabecular bone in female and male professional ballet dancers. 40 professional ballet dancers and 40 sex- and age-matched non-exercising controls volunteered. Femoral bone density was scanned by dual-energy X-ray absorptiometry (DXA) scan. A 3D-DXA software was used to analyse trabecular and cortical bone. Anthropometry, maturation (Tanner staging), menstrual parameters (age at menarche and primary amenorrhea), energy availability and nutritional analysis (3-day record) were also assessed.Compared to non-exercising participants, dancers exhibited significantly higher volumetric density for integral, cortical and trabecular bone, and thicker cortex at the femur. Ballet dancers demonstrated lower body weight compared to controls (p < 0.01). Female dancers had their menarche later than controls, and the prevalence of primary amenorrhea were significantly higher in dancers than controls (p < 0.01). Dancer’s energy availability was below the normal range (<30 kcal/kgFFM/day). Despite the presence of certain osteoporosis risk factors such as low energy availability, primary amenorrhoea and lower body weight, professional ballet dancers revealed higher bone density for both cortical and trabecular bone compartments compared to controls.

Purpose: To evaluate the prevalence of dehydration in occupational settings and contextualize findings to effects on performance in cognitively dominated tasks, simple and complex motor tasks during moderate and high heat stress.

Methods: The study included an occupational part with hydration assessed in five industries across Europe with urine samples collected from 139 workers and analyzed for urine specific gravity. In addition, laboratory experiments included eight male participants completing mild-intensity exercise once with full fluid replacement to maintain euhydration, and once with restricted water intake until the dehydration level corresponded to 2% bodyweight deficit. Following familiarization, euhydration and dehydration sessions were completed on separate days in random order (cross-over design) with assessment of simple motor (target pinch), complex motor (visuo-motor tracking), cognitive (math addition) and combined motor-cognitive (math and pinch) performance at baseline, at 1°C (MOD) and 2°C (HYPER) delta increase in body core temperature.

Results: The field studies revealed that 70% of all workers had urine specific gravity values ≥1.020 corresponding to the urine specific gravity (1.020±0.001) at the end of the laboratory dehydration session. At this hydration level, HYPER was associated with reductions in simple motor task performance by 4±1%, math task by 4±1%, math and pinch by 9±3% and visuo-motor tracking by 16±4% (all P<0.05 compared to baseline), whereas no significant changes were observed when the heat stress was MOD (P>0.05). In the euhydration session, HYPER reduced complex (tracking) motor performance by 10±3% and simple pinch by 3±1% (both P<0.05, compared to baseline), while performance in the two cognitively dominated tasks were unaffected when dehydration was prevented (P>0.05).

Conclusion: Dehydration at levels commonly observed across a range of occupational settings with environmental heat stress aggravates the impact of hyperthermia on performance in tasks relying on combinations of cognitive function and motor response accuracy.

Background: Atrial natriuretic peptide increases lipolysis in human adipocytes by binding to natriuretic peptide receptor-A (NPRA). The aim of the current study was to examine the associations of NPRA mRNA of subcutaneous adipose tissue with fat mass, fat-free mass, body mass index (BMI) and arterial blood pressure in medication-free healthy men. Method: Thirty-two volunteers [age (years): 36.06±7.36, BMI: 27.60±4.63 (kg/m 2)] underwent assessments of body height/weight, % fat mass, fat-free mass (kg), blood pressure, and a subcutaneous adipose tissue biopsy via a surgical technique. Results: We found that NPRA mRNA was negatively associated with % fat mass (r=-0.40, R 2=0.16, p=0.03) and BMI (r=-0.45, R 2=0.20, p=0.01). Cohen’s f 2 effect size analyses showed a small effect size between NPRA mRNA and BMI ( f 2 =0.25). One-way analysis of variance with Bonferroni post-hoc tests showed a tendency for mean differences of NPRA mRNA across BMI categories (p=0.06). This was confirmed by Cohen’s d effect size analyses revealing a large effect size of NPRA mRNA between obese individuals (BMI≥30 kg/m 2) and either normal weight (BMI=19-25 kg/m 2; d=0.94) or overweight (BMI=25-30 kg/m 2; d=1.12) individuals. Conclusions: NPRA mRNA is negatively associated with % fat mass and BMI in medication-free healthy men, suggesting a possible role of NPRA in the control of fat mass accumulation.

The aim of this study was to investigate the impact of aging and sex on athletic performance during the 7-day Marathon des Sables (MdS) in the Sahara Desert. Anonymous data for age, sex, and average running speed (km/h) for all the athletes who registered in the MdS during the period 2000-2015 were retrieved from the official website of the race and other endurance websites. Participants were distributed into the following age groups: 18-22 yrs, 23-27 yrs, 28-32 yrs, 33-37 yrs, 38-42 yrs, 43-47 yrs, 48-52 yrs, 53-57 yrs, 58-62 yrs, 63-67 yrs, and 68-80 yrs. Average running speed (km/h) during the entire race was used to characterize athletic performance. Results showed that the number of participants in the MdS has been steadily increasing from 570 in the year 2000 to 1,329 in the year 2015 (p < 0.001). Men (5.78 ± 1.55 km/h) demonstrate statistically increased performance throughout the MdS compared to women (5.04 ± 1.25 km/h). Abandonment data show that approximately 6.5% of the athletes do not complete the race. The highest performance in the MdS is achieved by athletes 33-42 years-old (p < 0.05). Athletes competing in the MdS are as old as 80 years and the number of athletes older than 52-years-old is increasing. It is concluded that the highest performance in the MdS is achieved by athletes 33-42 years. Nevertheless, ageing past 42 years is associated with decreased performance. Given the steadily increased participation of athletes aged > 52 years, future studies should investigate the physiological impact of this extreme event on elderly individuals during and following the race.

The association of genetic polymorphisms with low bone mineral density in elite athletes have not been considered previously. The present study found that bone mass phenotypes in elite and pre-elite dancers are related to genetic variants at the Wnt/β-catenin and ER pathways.

Introduction: Some athletes (e.g. gymnasts, dancers, swimmers) are at increased risk for low bone mineral density (BMD) which, if untreated, can lead to osteoporosis. To investigate the association of genetic polymorphisms in the oestrogen receptor (ER) and the Wnt/β-catenin signalling pathways with low BMD in elite and pre-elite dancers (impact sport athletes).

Methods: The study included three phases: (1) 151 elite and pre-elite dancers were screened for the presence of low BMD and traditional osteoporosis risk factors (low body weight, menstrual disturbances, low energy availability); (2) a genetic association study was conducted in 151 elite and pre-elite dancers and age- and sex- controls; (3) serum sclerostin was measured in 101 pre-elite dancers and age- and sex-matched controls within a 3-year period.

Results: Eighty dancers revealed low BMD: 56.3% had at least one traditional osteoporosis risk factor, whereas 28.6% did not display any risk factor (37.2% revealed traditional osteoporosis risk factors, but had normal BMD). Body weight, menstrual disturbances and energy availability did not fully predict bone mass acquisition. Instead, genetic polymorphisms in the ER and Wnt/β-catenin pathways were found to be risk factors for low BMD in elite dancers. Sclerostin was significantly increased in dancers compared to controls during the 3-year follow-up (p < 0.05).

Conclusions: Elite and pre-elite dancers demonstrate high prevalence of low BMD, which is likely related to genetic variants at the Wnt/β-catenin and ER pathways and not to factors usually associated with BMD in athletes (body weight, menstrual disturbances, energy deficiency).

We examined if physical characteristics could be used to predict cooling time during cold water immersion (CWI, 2 °C) following exertional hyperthermia (rectal temperature ≥39.5 °C) in a physically heterogeneous group of men and women (n = 62). Lean body mass was the only significant predictor of cooling time following CWI (R2 = 0.137; P < 0.001); however, that prediction did not provide the precision (mean residual square error: 3.18 ± 2.28 min) required to act as a safe alternative to rectal temperature measurements.

Introduction: The aim of this study was to investigate the impact of heat acclimatization on athletic performance during the 7-day Marathon des Sables (MdS) which takes place in the Sahara Desert. Methods: Anonymous data for nationality and average running speed (km/h) of all runners who ran the MdS during the period 2000–2015 were collected from the official website of the race and other related websites. Average maximum temperature for each runner’s country during the month preceding the MdS was collected from www.weatherbase.com. Athletes were divided into two Torigin groups as follows: 25 to 15 ̊C (i.e., cold countries) and 15 to 35 ̊C (i.e., warm countries). Results: Overall, 12 467 (10 828 men; 1639 women) athletes from 78 countries (37 cold; 41 warm) participated in the MdS during the 16-year study period. The ambient temperature of these countries one month prior to the MdS ranged from 24.2 to 34.4 ̊C. Athletes’ average running speed during the MdS ranged from 2.9 to 13.4 km/h. Moreover, athletes who originated from warm countries ran the MdS 10.7% faster compared to athletes from cold countries. Conclusion: The natural heat acclimatization achieved by living in warmer countries seems to provide an advantage during the MdS.

The aim of this study was to examine the effect of natural ageing on heart rate variability during and following exercise-induced heat stress in females. Eleven young (∼24 years) and 13 older (∼51 years), habitually active females completed an experimental session consisting of baseline rest, moderate intensity intermittent exercise (four 15-min bouts separated by 15-min recovery) and 1-hour of final recovery in a hot and dry (35°C, 20% relative humidity) environment. Respiratory and heart rate recordings were continuously logged with 10-min periods analysed at the end of: baseline rest; each of the exercise and recovery bouts; and during the 1-hour final recovery period. Comparisons over time during exercise and recovery, and between groups were conducted via two-way repeated-measures ANCOVAs with rest values as the covariate. During baseline rest, older females exhibited lower heart rate variability compared to young females with similar levels of respiration and most (∼71-79%) heart rate variability measures during repeated exercise and recovery. However, older females exhibited heart rate variability metrics suggestive of greater parasympathetic modulation (greater long axis of Poincare plot, cardiac vagal index; lower low-high frequency ratio) during repeated exercise with lower indices during the latter stage of prolonged recovery (less very low frequency component, Largest Lyapunov Exponent; greater cardiac sympathetic index). The current study documented several unique, age-dependent differences in heart rate variability, independent of respiration, during and following exercise-induced heat stress for females that may assist in the detection of normal heat-induced adaptations as well as individuals vulnerable to heat stress.


The relationship between non-thermoneutral zone temperatures with increased mortality in elderly individuals is well established. However, less is known regarding the effect of night-time temperature on mortality in elderly individuals. The aim of this study was to investigate the association between night-time temperature and mortality in elderly people (≥ 70 years) in Cyprus.


All-cause mortality data covering the period 2004-2014 were retrieved from the Health Monitoring Unit of the Cypriot Ministry of Health. Midnight (00:00) temperature data from weather stations across the island of Cyprus covering the same time period were collected from www.wunderground.com. Night-time temperatures were categorized into six 5-degree Celsius categories (≤ 8 ℃, 9-13 ℃, 14-18 ℃, 19-23 ℃, 24-28 ℃, and ≥ 29 ℃). The 19-23 ℃ category was defined as thermoneutral zone.


A total of 43,107 elderly individuals died during the monitored period and the most prevalent cause of death was “diseases of the circulatory system” (41.5%; p < 0.001). Mortality due to diseases of the circulatory system was significantly reduced when night-time temperature was at the thermoneutral zone during the previous night (p < 0.05). The prevalence of deaths due to circulatory causes was higher for females compared to males (p < 0.001) (Cohen’s d = 0.34). Furthermore, there was higher prevalence of deaths during extreme night time temperatures compared with thermoneutral zone (0.24 ≥ Cohen’s d ≤ 1.01).


Mortality due to circulatory causes, the most prevalent cause of death in Cyprus, is increased when night-time temperature is above or below the thermoneutral zone.

Background: Occupational heat strain (ie, the effect of environmental heat stress on the body) directly threatens workers’ ability to live healthy and productive lives. We estimated the effects of occupational heat strain on workers’ health and productivity outcomes. Methods: Following PRISMA guidelines for this systematic review and meta-analysis, we searched PubMed and Embase from database inception to Feb 5, 2018, for relevant studies in any labour environment and at any level of occupational heat strain. No restrictions on language, workers’ health status, or study design were applied. Occupational heat strain was defined using international health and safety guidelines and standards. We excluded studies that calculated effects using simulations or statistical models instead of actual measurements, and any grey literature. Risk of bias, data extraction, and sensitivity analysis were performed by two independent investigators. Six random-effects meta-analyses estimated the prevalence of occupational heat strain, kidney disease or acute kidney injury, productivity loss, core temperature, change in urine specific gravity, and odds of occupational heat strain occurring during or at the end of a work shift in heat stress conditions. The review protocol is available on PROSPERO, registration number CRD42017083271. Findings: Of 958 reports identified through our systematic search, 111 studies done in 30 countries, including 447 million workers from more than 40 different occupations, were eligible for analysis. Our meta-analyses showed that individuals working a single work shift under heat stress (defined as wet-bulb globe temperature beyond 22·0 or 24·8°C depending on work intensity) were 4·01 times (95% CI 2·45–6·58; nine studies with 11 582 workers) more likely to experience occupational heat strain than an individual working in thermoneutral conditions, while their core temperature was increased by 0·7°C (0·4–1·0; 17 studies with 1090 workers) and their urine specific gravity was increased by 14·5% (0·0031, 0·0014–0·0048; 14 studies with 691 workers). During or at the end of a work shift under heat stress, 35% (31–39; 33 studies with 13 088 workers) of workers experienced occupational heat strain, while 30% (21–39; 11 studies with 8076 workers) reported productivity losses. Finally, 15% (11–19; ten studies with 21 721 workers) of individuals who typically or frequently worked under heat stress (minimum of 6 h per day, 5 days per week, for 2 months of the year) experienced kidney disease or acute kidney injury. Overall, this analysis include a variety of populations, exposures, and occupations to comply with a wider adoption of evidence synthesis, but resulted in large heterogeneity in our meta-analyses. Grading of Recommendations, Assessment, Development and Evaluation analysis revealed moderate confidence for most results and very low confidence in two cases (average core temperature and change in urine specific gravity) due to studies being funded by industry. Interpretation: Occupational heat strain has important health and productivity outcomes and should be recognised as a public health problem. Concerted international action is needed to mitigate its effects in light of climate change and the anticipated rise in heat stress.

Patients with multiple sclerosis experience many complications that gradually lead them to comorbidity and disability. Exercise could prevent and ameliorate the symptoms that comorbidity or inactivity generate. However, until recently it was suggested that multiple sclerosis patients should not participate in exercise training programs because these patients are characterized by thermoregulatory failure and the heat stress due to physical work could exacerbate the disease symptoms. Furthermore, taken into account that 60–80% of the multiple sclerosis patients present adverse clinical symptoms when their body temperature is increased (not only due to physical working but even when immerse in hot water or by exposure to infrared lamps or to the sun), the need for the development of treatment strategies to overcome the thermoregulatory problem in these patients is crucial. Given that pre-cooling has been proposed as an effective method, the aim of this systematic review is to discuss the current knowledge for the effects of cooling therapy on the functional capacity of multiple sclerosis patients. The relevant literature includes many articles, but only a handful of studies published thus far have used a cooling intervention in multiple sclerosis patients and have examined the effects of pre-cooling on functional capacity. These studies used active cooling methods, namely garments or other material that are cooled by circulating liquid through a tube, as well as passive, cooling methods. Passive cooling methods include passive cooling garments or other material namely garments that have ice or gel packs inside them. Overall, the results of all the studies analysed in this review demonstrated that pre-cooling therapy can prevent the symptom worsening due to increased body temperature in multiple sclerosis patients without causing adverse effects. Therefore, such strategies could serve as a complimentary therapeutic approach in multiple sclerosis patients.

Workers in many industries are required to perform arduous work in high heat-stress conditions, which can lead to rapid increases in body temperature that elevate the risk of heat-related illness and even death. Traditionally, effort to mitigate work-related heat injury has been directed toward the assessment of environmental heat stress (e.g., wet-bulb globe temperature), rather than toward the associated physiological strain responses (e.g., heart rate and skin and core temperatures). However, because a worker’s physiological response to a given heat stress is modified independently by inter-individual factors (e.g., age, sex, chronic disease, others) and intra-individual factors both within (e.g., medication use, fitness, acclimation and hydration state, others) and beyond (e.g., shift duration, illness, others) the worker’s control, it becomes challenging to protect workers on an individual basis from heat-related injury without assessing those physiological responses. Recent advancements in wearable technology have made it possible to monitor one or more physiological indices of heat strain. Nonetheless, information on the utility of the wearable systems available for assessing occupational heat strain is unavailable. This communication is therefore directed toward identifying the physiological indices of heat strain that may be quantified in the workplace and evaluating the wearable monitoring systems available for assessing those responses. Finally, emphasis is placed on the barriers associated with implementing these devices to assist in mitigating work-related heat injury. This information is fundamental for protecting worker health and could also be utilized to prevent heat illnesses in vulnerable people during leisure or athletic activities.

The aim of this systematic review was to review the recent literature regarding the effect of heat waves on mortality in elderly adults. A systematic search of the literature, was conducted by two reviewers during March 2018, using three electronic databases (PubMed, Web of Science, and Scopus). The PRISMA guidelines were used for the quality assessment of the published studies. The literature search identified a total of 345 articles, while only 24 studies met the inclusion criteria and were included in this analysis. Overall, the results from these studies show that, although recent advances in technology allow scientists to predict heat waves, thereby enabling health agencies to alert the public with heat advisories, the number of heat wave-induced deaths remains high. The underlying reasons for these increases in heat-wave-induced mortality remains unclear, highlighting the need for developing evidence-based thresholds for the activation and implementation of actions plans to protect the health of heat-vulnerable elderly populations.

Rising environmental temperatures represent a major threat to human health. The activation of heat advisories using evidence-based thresholds for high-risk outdoor ambient temperatures have been shown to be an effective strategy to save lives during hot weather. However, although the relationship between weather and human health has been widely defined by outdoor temperature, corresponding increases in indoor temperature during heat events can also be harmful to health especially in vulnerable populations. In this review, we discuss our current understanding of the relationship between outdoor temperature and human health and examine how human health can also be adversely influenced by high indoor temperatures during heat events. Our assessment of the existing literature revealed a high degree of variability in what can be considered an acceptable indoor temperature because there are differences in how different groups of people may respond physiologically and behaviorally to the same living environment. Finally, we demonstrate that both non-physiological (e.g., geographical location, urban density, building design) and physiological (e.g., sex, age, fitness, state of health) factors must be considered when defining an indoor temperature threshold for preserving human health in a warming global climate.

The study examined the effects of a motivational self-talk intervention on endurance cycling performance in hot conditions. Participants were 16 physically active adult men. After a baseline VO2 peak assessment and two training sessions, participants completed a 30 min cycling trial in a hot environment (35°C, 45% relative humidity) while maintaining a steady rate of perceived exertion. Participants of the intervention group produced greater power output during the final third of the trial. Findings suggest that the self-talk strategy seems to have compromised the aversive effects of the demanding environmental conditions and provide support for the psychobiological model of endurance performance.

Population aging and global warming generate important public health risks, as older adults have increased susceptibility to heat stress (SHS). We defined and validated sex-specific screening criteria for SHS during work and leisure activities in hot environments in individuals aged 31-70 years using age, anthropometry, and cardiorespiratory fitness. A total of 123 males and 44 females [44 ± 14 years; 22.9 ± 7.4% body fat; 40.3 ± 8.6 peak oxygen uptake (mlO2/kg/min)] participated, separated into the Analysis (n = 111) and Validation (n = 56) groups. Within these groups, participants were categorized into YOUNG (19-30 years; n = 47) and OLDER (31-70 years; n = 120). All participants performed exercise in the heat inside a direct calorimeter. Screening criteria for OLDER participants were defined from the Analysis group and were cross-validated in the Validation group. Results showed that 30% of OLDER individuals in the Analysis group were screened as SHS positive. A total of 274 statistically valid (p < 0.05) criteria were identified suggesting that OLDER participants were at risk for SHS when demonstrating two or more of the following (males/females): age ≥ 53.0/55.8 years; body mass index ≥29.5/25.7 kg/m2; body fat percentage ≥ 28.8/34.9; body surface area ≤2.0/1.7 m2; peak oxygen uptake ≤48.3/41.4 mlO2/kg fat free mass/min. In the Validation group, McNemar χ2 comparisons confirmed acceptable validity for the developed criteria. We conclude that the developed criteria can effectively screen individuals 31-70 years who are at risk for SHS during work and leisure activities in hot environments and can provide simple and effective means to mitigate the public health risks caused by heat exposure.

We evaluated the extent to which age, cardiorespiratory fitness, and body fat can independently determine whole-body heat loss (WBHL) in 87 otherwise healthy adults. We show that increasing age is a major predictor for decreasing WBHL in otherwise healthy adults (aged 20-70 years), accounting for 40% of the variation in the largest study to date. While greater body fat also had a minor detrimental impact on WBHL, there was no significant role for cardiorespiratory fitness.


This study was designed to determine whether age-related impairments in whole-body heat loss, which are known to exist in dry heat, also occur in humid heat in women.


To evaluate this possibility, 10 young (25 ± 4 yr) and 10 older (51 ± 7 yr) women matched for body surface area (young, 1.69 ± 0.11; older, 1.76 ± 0.14 m2P = 0.21) and peak oxygen consumption (V˙O2peak) (young, 38.6 ± 4.6; older, 34.8 ± 6.6 mL·kg−1·min−1P = 0.15) performed four 15-min bouts of cycling at a fixed metabolic heat production rate (300 W; equivalent to ~45% V˙O2peak), each separated by a 15-min recovery, in dry (35°C, 20% relative humidity) and humid heat (35°C, 60% relative humidity). Total heat loss (evaporative ± dry heat exchange) and metabolic heat production were measured using direct and indirect calorimetry, respectively. Body heat storage was measured as the temporal summation of heat production and loss.


Total heat loss was lower in humid conditions compared with dry conditions during all exercise bouts in both groups (all P < 0.05), resulting in 49% and 39% greater body heat storage in young and older women, respectively (both P < 0.01). Total heat loss was also lower in older women compared with young women during exercise bouts 1, 2 and 3 in dry heat (all P < 0.05) and bouts 1 and 2 in humid heat (both P < 0.05). Consequently, body heat storage was 29% and 16% greater in older women compared with young women in dry and humid conditions, respectively (both P < 0.05).


Increasing ambient humidity reduces heat loss capacity in young and older women. However, older women display impaired heat loss relative to young women in both dry and humid heat, and may therefore be at greater risk of heat-related injury during light-to-moderate activity.

Introduction: In this study we (i) introduced time-motion analysis for assessing the impact of workplace heat on the work shift time spent doing labor (WTL) of grape-picking workers, (ii) examined whether seasonal environmental differences can influence their WTL, and (iii) investigated whether their WTL can be assessed by monitoring productivity or the vineyard manager’s estimate of WTL. Methods: Seven grape-picking workers were assessed during the summer and/or autumn via video throughout four work shifts. Results: Air temperature (26.8 ± 4.8°C), wet bulb globe temperature (WBGT; 25.2 ± 4.1°C), universal thermal climate index (UTCI; 35.2 ± 6.7°C), and solar radiation (719.1 ± 187.5 W/m2) were associated with changes in mean skin temperature (1.7 ± 1.8°C) (p < 0.05). Time-motion analysis showed that 12.4% (summer 15.3% vs. autumn 10.0%; p < 0.001) of total work shift time was spent on irregular breaks (WTB). There was a 0.8%, 0.8%, 0.6%, and 2.1% increase in hourly WTB for every degree Celsius increase in temperature, WBGT, UTCI, and mean skin temperature, respectively (p < 0.01). Seasonal changes in UTCI explained 64.0% of the seasonal changes in WTL (p = 0.017). Productivity explained 36.6% of the variance in WTL (p < 0.001), while the vineyard manager’s WTL estimate was too optimistic (p < 0.001) and explained only 2.8% of the variance in the true WTL (p = 0.456). Conclusion: Time-motion analysis accurately assesses WTL, evaluating every second spent by each worker during every work shift. The studied grape-picking workers experienced increased workplace heat, leading to significant labor loss. Monitoring productivity or the vineyard manager’s estimate of each worker’s WTL did not completely reflect the true WTL in these grape-picking workers.

Objective: The aim of this study was to evaluate the browning and origin of fatty acids (FAs) in the maintenance of triacylglycerol (TG) storage and/or as fuel for thermogenesis in perirenal adipose tissue (periWAT) and inguinal adipose tissue (ingWAT) of rats fed a low-protein, high-carbohydrate (LPHC) diet.

Methods: LPHC (6% protein, 74% carbohydrate) or control (C; 17% protein, 63% carbohydrate) diets were administered to rats for 15 d. The tissues were stained with hematoxylin and eosin for histologic analysis. The content of uncoupling protein 1 (UCP1) was determined by immunofluorescence. Levels of T-box transcription factor (TBX1), PR domain containing 16 (PRDM16), adipose triacylglycerol lipase (ATGL), hormone-sensitive lipase, lipoprotein lipase (LPL), glycerokinase, phosphoenolpyruvate carboxykinase (PEPCK), glucose transporter 4, β3-adrenergic receptor (AR), β1-AR, protein kinase A (PKA), adenosine-monophosphate-activated protein kinase (AMPK), and phospho-AMPK were determined by immunoblotting. Serum fibroblast growth factor 21 (FGF21) was measured using a commercial kit (Student’s t tests, P < 0.05).

Results: The LPHC diet increased FGF21 levels by 150-fold. The presence of multilocular adipocytes, combined with the increased contents of UCP1, TBX1, and PRDM16 in periWAT of LPHC-fed rats, suggested the occurrence of browning. The contents of β1-AR and LPL were increased in the periWAT. The ingWAT showed higher ATGL and PEPCK levels, phospho-AMPK/AMPK ratio, and reduced β3-AR and PKA levels.

Conclusion: These findings suggest that browning occurred only in the periWAT and that higher utilization of FAs from blood lipoproteins acted as fuel for thermogenesis. Increased glycerol 3-phosphate generation by glyceroneogenesis increased FAs reesterification from lipolysis, explaining the increased TG storage in the ingWAT.

Keywords: Brite; Energy expenditure; High-carbohydrate diet; Low-protein; Protein restriction; White adipose tissue.

In cool conditions, physiologic markers accurately predict endurance performance, but it is unclear whether thermal strain and perceived thermal strain modify the strength of these relationships. This study examined the relationships between traditional determinants of endurance performance and time to complete a 5-km time trial in the heat. Seventeen club runners completed graded exercise tests (GXT) in hot (GXTHOT; 32°C, 60% RH, 27.2°C WBGT) and cool conditions (GXTCOOL; 13°C, 50% RH, 9.3°C WBGT) to determine maximal oxygen uptake (V̇O2max), running economy (RE), velocity at V̇O2max (vV̇O2max), and running speeds corresponding to the lactate threshold (LT, 2 mmol.l−1) and lactate turnpoint (LTP, 4 mmol.l−1). Simultaneous multiple linear regression was used to predict 5 km time, using these determinants, indicating neither GXTHOT (R2 = 0.72) nor GXTCOOL (R2 = 0.86) predicted performance in the heat as strongly has previously been reported in cool conditions. vV̇O2max was the strongest individual predictor of performance, both when assessed in GXTHOT (r = −0.83) and GXTCOOL (r = −0.90). The GXTs revealed the following correlations for individual predictors in GXTHOT; V̇O2max r = −0.7, RE r = 0.36, LT r = −0.77, LTP r = −0.78 and in GXTCOOL; V̇O2max r = −0.67, RE r = 0.62, LT r = −0.79, LTP r = −0.8. These data indicate (i) GXTHOT does not predict 5 km running performance in the heat as strongly as a GXTCOOL, (ii) as in cool conditions, vV̇O2max may best predict running performance in the heat.

Adipose tissue biopsies offer tissue samples that, upon analysis, may provide insightful overviews of mechanisms relating to metabolism and disease. To obtain subcutaneous adipose tissue biopsies in the abdominal area, researchers and physicians use either a surgical or a needle-based technique. However, surgical subcutaneous fat biopsies can offer tissue samples that may provide a more comprehensive overview of the complexities of biological indices in white adipose tissue. Usually, a surgical adipose tissue biopsy includes a diathermy treatment for cauterizing blood vessels to prevent excessive bleeding. Nevertheless, side effects, such as flash fires and skin lesions in the tissue, have been reported after diathermy. Therefore, we aimed to standardize a surgical abdominal adipose tissue biopsy performed under local anesthesia using a non-diathermy method. We conducted 115 subcutaneous adipose tissue biopsies in healthy men using a non-diathermy abdominal surgical biopsy method. Our results showed three cases of excessive post-operation bleeding out of 115 operations (2.61%).In conclusion, our standardized subcutaneous abdominal adipose tissue surgical biopsy using a non-diathermy method can be safely applied to healthy men at the bedside, with minimal side effects.

Regular exercise and diet may contribute to white adipose tissue (WAT) conversion into a brown adipose-like phenotype that may increase resting energy expenditure (REE), leading to weight loss. We examined the relationship between REE, physical activity (PA) participation and diet with browning formation markers of subcutaneous WAT in healthy men. We assessed REE, diet and body composition of 32 healthy men [age (years): 36.06 ± 7.36, body mass index (BMI): 27.06 ± 4.62 (kg/m 2 )]. Participants also underwent measurements of PA [metabolic equivalent (MET)-min/week] using the International Physical Activity Questionnaire (IPAQ), while they undertook a subcutaneous fat biopsy from the abdominal region to assess the mRNA expressions of uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), peroxisome proliferator-activated receptor alpha (PPARα) and peroxisome proliferator-activated receptor gamma (PPARγ). We found no associations between the UCP1, PGC-1α, PPARα and PPARγ mRNAs with REE, PA levels and diet (p > 0.05). However, the PGC-1α, PPARα and PPARγ mRNAs were more expressed in individuals displaying moderate rather than low PA levels (p < 0.05). Furthermore, PGC-1α, PPARα and PPARγ mRNAs were negatively correlated with fat mass percentage (p < 0.05). PGC-1α and PPARα mRNAs were also negatively correlated with BMI, while PGC-1α mRNA was inversely associated with waist-to-hip ratio (p < 0.05). REE, PA levels and diet are not associated with browning formation indices of subcutaneous adipose tissue in healthy adult men.

Purpose: The American Conference of Governmental and Industrial Hygienists (ACGIH®) Threshold Limit Values (TLV® guidelines) for work in the heat consist of work-rest (WR) allocations designed to ensure a stable core temperature that does not exceed 38°C. However, the TLV® guidelines have not been validated in older workers. This is an important shortcoming given that adults as young as 40 years demonstrate impairments in their ability to dissipate heat. We therefore evaluated body temperature responses in older adults during work performed in accordance to the TLV® recommended guidelines.

Methods: On three occasions, 9 healthy older (58 ± 5 years) males performed a 120-min work-simulated protocol in accordance with the TLV® guidelines for moderate-to-heavy intensity work (360 W fixed rate of heat production) in different wet-bulb globe temperatures (WBGT). The first was 120 min of continuous (CON) cycling at 28.0°C WBGT (CON[28°C]). The other two protocols were 15-min intermittent work bouts performed with different WR cycles and WBGT: (i) WR of 3:1 at 29.0°C (WR3:1[29°C]) and (ii) WR of 1:1 at 30.0°C (WR1:1[30°C]). Rectal temperature was measured continuously. The rate of change in mean body temperature was determined via thermometry (weighting coefficients: rectal, 0.9; mean skin temperature, 0.1) and direct calorimetry.

Results: Rectal temperature exceeded 38°C in all participants in CON[28°C] and WR3:1[29°C] whereas a statistically similar proportion of workers exceeded 38°C in WR1:1[30°C] (χ2; P = 0.32). The average time for rectal temperature to reach 38°C was: CON[28°C], 53 ± 7; WR3:1[29°C], 79 ± 11; and WR1:1[30°C], 100 ± 29 min. Finally, while a stable mean body temperature was not achieved in any work condition as measured by thermometry (i.e., >0°C·min-1; all P<0.01), heat balance as determined by direct calorimetry was achieved in WR3:1[29°C] and WR1:1[30°C] (both P ≥ 0.08).

Conclusion: Our findings indicate that the TLV® guidelines do not prevent body core temperature from exceeding 38°C in older workers. Furthermore, a stable core temperature was not achieved within safe limits (i.e., ≤38°C) indicating that the TLV® guidelines may not adequately protect all individuals during work in hot conditions.

Background: Professional dancers are at risk of developing low bone mineral density (BMD). However, whether low BMD phenotypes already exist in pre-vocational dance students is relatively unknown.
Aim: To cross-sectionally assess bone mass parameters in female dance students selected for professional dance training (first year vocational dance students) in relation to aged- and sex-matched controls.
Methods: 34 female selected for professional dance training (10.9yrs ±0.7) and 30 controls (11.1yrs ±0.5) were examined. Anthropometry, pubertal development (Tanner) and dietary data (3- day food diary) were recorded. BMD and bone mineral content (BMC) at forearm, femur neck (FN) and lumbar spine (LS) were assessed using Dual-Energy X-Ray Absorptiometry. Volumetric densities were estimated by calculating bone mineral apparent density (BMAD).
Results: Dancers were mainly at Tanner pubertal stage I (vs. stage IV in controls, p<0.001), and demonstrated significantly lower body weight (p<0.001) and height (p<0.01) than controls. Calorie intake was not different between groups, but calcium intake was significantly greater in dancers (p<0.05). Dancers revealed a significantly lower BMC and BMD values at all anatomical sites (p<0.001), and significantly lower BMAD values at the LS and FN (p<0.001). When adjusted for covariates (body weight, height, pubertal development and calcium intake), dance students continued to display a significantly lower BMD and BMAD at the FN (p<0.05; p<0.001) at the forearm (p<0.01).
Conclusion: Before undergoing professional dance training, first year vocational dance students demon- strated inferior bone mass compared to controls. Longitudinal models are required to assess how bone health-status changes with time throughout professional training.

According to existing literature, bone health in ballet dancers is controversial. We have verified that, compared to controls, young female and male vocational ballet dancers have lower bone mineral density (BMD) at both impact and non-impact sites, whereas female professional ballet dancers have lower BMD only at non-impact sites.

Introduction: The aims of this study were to (a) assess bone mineral density (BMD) in vocational (VBD) and professional (PBD) ballet dancers and (b) investigate its association with body mass (BM), fat mass (FM), lean mass (LM), maturation and menarche.

Methods: The total of 152 VBD (13 ± 2.3 years; 112 girls, 40 boys) and 96 controls (14 ± 2.1 years; 56 girls, 40 boys) and 184 PBD (28 ± 8.5 years; 129 females, 55 males) and 160 controls (27 ± 9.5 years; 110 female, 50 males) were assessed at the lumbar spine (LS), femoral neck (FN), forearm and total body by dual-energy X-ray absorptiometry. Maturation and menarche were assessed via questionnaires.

Results: VBD revealed lower unadjusted BMD at all anatomical sites compared to controls (p < 0.001); following adjustments for Tanner stage and gynaecological age, female VBD showed similar BMD values at impact sites. However, no factors were found to explain the lower adjusted BMD values in VBD (female and male) at the forearm (non-impact site), nor for the lower adjusted BMD values in male VBD at the FN. Compared to controls, female PBD showed higher unadjusted and adjusted BMD for potential associated factors at the FN (impact site) (p < 0.001) and lower adjusted at the forearm (p < 0.001). Male PBD did not reveal lower BMD than controls at any site.

Conclusions: Both females and males VBD have lower BMD at impact and non-impact sites compared to control, whereas this is only the case at non-impact site in female PBD. Maturation seems to explain the lower BMD at impact sites in female VBD.

Background: Little is known about cold-related mortality in south Europe. The aim of this study was to investigate the association between extreme cold weather and mortality in Greece.

Methods: Daily mortality data covering the period 1999-2012 were retrieved through the Hellenic Statistical Authority Archive. 24-hour mean temperature was collected from 16 weather stations spread throughout the country. Analyses were focused on days with extremely low temperatures (5th percentile) as well as on the following seven days.

Results: The two leading death causes during extreme cold weather were diseases of the nervous system (36.5%) and diseases of the respiratory system (26.8%). The prevalence of deaths due the aforementioned causes was significantly increased on extreme cold weather (and following seven days) when compared to warm temperature days (temperatures ranging between 15-20 °C; p < 0.001). In addition, temperature during extreme cold weather was significantly associated with increased mortality; a decrease of 1 °C in mean temperature significantly increased mortality by 2.8% (p < 0.001). On the first and second day following extreme cold weather, mortality increased by 0.6% (p < 0.001) and 0.8% (p < 0.01), respectively.

Conclusion: Extreme cold weather is associated with all-cause mortality and also with cause-specific mortality. During extreme cold days, the diseases of the nervous and respiratory systems rise the most in Greece.

In the aftermath of the Paris Agreement, there is a crucial need for scientists in both thermal physiology and climate change research to develop the integrated approaches necessary to evaluate the health, economic, technological, social, and cultural impacts of 1.5°C warming. Our aim was to explore the fidelity of remote temperature measurements for quantitatively identifying the continuous redistribution of heat within both the Earth and the human body. Not accounting for the regional distribution of warming and heat storage patterns can undermine the results of thermal physiology and climate change research. These concepts are discussed herein using two parallel examples: the so-called slowdown of the Earth’s surface temperature warming in the period 1998-2013; and the controversial results in thermal physiology, arising from relying heavily on core temperature measurements. In total, the concept of heat is of major importance for the integrity of systems, such as the Earth and human body. At present, our understanding about the interplay of key factors modulating the heat distribution on the surface of the Earth and in the human body remains incomplete. Identifying and accounting for the interconnections among these factors will be instrumental in improving the accuracy of both climate models and health guidelines.

Understanding the impact of regular exercise training on uncoupling protein 1 (UCP1) activity in classical brown adipose tissue (CBAT) is vital to our knowledge of whole-body thermogenic activity. The purpose of this systematic review was to evaluate the available experimental evidence on the effect of regular exercise training on UCP1 expression in CBAT. We performed a literature search using PubMed (1966-2016), Scopus, and EMBASE (1974-2016). Studies in any language that examined the effect of regular exercise training on UCP1 expression in CBAT, and not white adipose tissue (WAT), were eligible. Reviews, editorials, and conference proceedings were excluded. Nine studies fulfilled the set criteria. Risk of bias was assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool. The quality of reporting the results in the included studies was assessed using the 38-item checklist of the Animal Research Reporting of In Vivo Experiments (ARRIVE). Based on the evidence available and a comprehensive analysis of different confounding factors, we conclude that regular exercise training does not represent a major stimulus of UCP1 expression in CBAT. However, regular exercise training may induce adaptive responses to CBAT thermogenic activity in cases where: (i) animals consume a high-fat diet, (ii) exercise is combined with cold exposure, and (iii) animals show endogenously low UCP1 levels. Finally, it is important to note an inconsistency in the results from the analysed studies, which may be attributed to a number of confounding factors, increased risk of bias, as well as low quality of reporting the results.

Cardio-metabolic diseases (CMDs) comprise a cluster of risk factors that contribute to chronic pathological conditions with adverse consequences for cardiovascular function and metabolic processes. A wide range of CMD prevalence rates among different ethnic groups has been documented. In view of accumulated evidence, there is a trend toward increasing CMD prevalence rates in Eastern Europe and Western Asia. Numerous studies have revealed an association between uncoupling protein 1 (UCP1) gene variants and CMDs. UCP1 activity is essential for brown adipose tissue (BAT)-mediated thermogenesis. Experimental animal studies and epidemiological studies in humans highlight the significance of BAT-mediated thermogenesis in protecting against obesity and maintaining a lean phenotype. We hypothesize that the genetic variation in UCP1 gene expression observed among different ethnic groups could contribute to the ethnic-specific predisposition to CMD development. Constructing such prevalence maps of UCP1 gene variants could contribute significantly into identifying high-risk ethnic groups predisposed to the development of CMDs, and further shaping public health policies by the improvement of existing preventive and management strategies.

Background: Exercise may activate a brown adipose-like phenotype in white adipose tissue. The aim of this systematic review was to identify the effects of physical activity on the link between peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1a) and fibronectin type III domain-containing protein 5 (FNDC5) in muscle, circulating Irisin and uncoupling protein one (UCP1) of white adipocytes in humans. Methods: Two databases (PubMed 1966 to 08/2016 and EMBASE 1974 to 08/2016) were searched using an appropriate algorithm. We included articles that examined physical activity and/or exercise in humans that met the following criteria: a) PGC-1a in conjunction with FNDC5 measurements, and b) FNDC5 and/or circulating Irisin and/or UCP1 levels in white adipocytes. Results: We included 51 studies (12 randomised controlled trials) with 2474 participants. Out of the 51 studies, 16 examined PGC-1a and FNDC5 in response to exercise, and only four found increases in both PGC-1a and FNDC5 mRNA and one showed increased FNDC5 mRNA. In total, 22 out of 45 studies that examined circulating Irisin in response to exercise showed increased concentrations when ELISA techniques were used; two studies also revealed increased Irisin levels measured via mass spectrometry. Three studies showed a positive association of circulating Irisin with physical activity levels. One study found no exercise effects on UCP1 mRNA in white adipocytes. Conclusions: The effects of physical activity on the link between PGC-1a, FNDC5 mRNA in muscle and UCP1 in white human adipocytes has attracted little scientific attention. Current methods for Irisin identification lack precision and, therefore, the existing evidence does not allow for conclusions to be made regarding Irisin responses to physical activity. We found a contrast between standardised review methods and accuracy of the measurements used. This should be considered in future systematic reviews.

“Welcome to the world of Temperature!” With these words the present journal was launched as a publication with special focus on temperature issues and their essential importance for life.1 The shared focus and international collaboration is more relevant than ever as our future world will involve more heat and increased prevalence of heat-induced issues. Even with the least pessimistic climate scenarios predicting only small increases in the average global temperature, we will face higher frequencies of heat waves and marked increase in the total number of hot days in the vulnerable regions of the world.

We examined whether older individuals experience greater levels of hyperthermia and cardiovascular strain during an extreme heat exposure compared to young adults. During a 3-hour extreme heat exposure (44°C, 30% relative humidity), we compared body heat storage, core temperature (rectal, visceral) and cardiovascular (heart rate, cardiac output, mean arterial pressure, limb blood flow) responses of young adults (n = 30, 19-28 years) against those of older adults (n = 30, 55-73 years). Direct calorimetry measured whole-body evaporative and dry heat exchange. Body heat storage was calculated as the temporal summation of heat production (indirect calorimetry) and whole-body heat loss (direct calorimetry) over the exposure period. While both groups gained a similar amount of heat in the first hour, the older adults showed an attenuated increase in evaporative heat loss (p < 0.033) in the first 30-min. Thereafter, the older adults were unable to compensate for a greater rate of heat gain (11 ± 1 ; p < 0.05) with a corresponding increase in evaporative heat loss. Older adults stored more heat (358 ± 173 kJ) relative to their younger (202 ± 92 kJ; p < 0.001) counterparts at the end of the exposure leading to greater elevations in rectal (p = 0.043) and visceral (p = 0.05) temperatures, albeit not clinically significant (rise < 0.5°C). Older adults experienced a reduction in calf blood flow (p < 0.01) with heat stress, yet no differences in cardiac output, blood pressure or heart rate. We conclude, in healthy habitually active individuals, despite no clinically observable cardiovascular or temperature changes, older adults experience greater heat gain and decreased limb perfusion in response to 3-hour heat exposure.

Purpose: We evaluated core temperature responses and the change in body heat content (ΔHb) during work performed according to the ACGIH threshold limit values (TLV) for heat stress, which are designed to ensure a stable core temperature that does not exceed 38.0°C.

Methods: Nine young males performed a 120-min work protocol consisting of cycling at a fixed rate of heat production (360 W). On the basis of the TLV, each protocol consisted of a different work-rest (WR) allocation performed in different wet-bulb globe temperatures (WBGT). The first was 120 min of continuous (CON) cycling at 28.0°C WBGT (CON[28.0°C]). The remaining three protocols were intermittent work bouts (15-min duration) performed at various WR and WBGT: (i) WR of 3:1 at 29.0°C (WR3:1[29.0°C]), (ii) WR of 1:1 at 30.0°C (WR1:1[30.0°C]), and (iii) WR of 1:3 at 31.5°C (WR1:3[31.5°C]) (total exercise time: 90, 60, and 30 min, respectively). The change in rectal (ΔTre) and mean body temperature (ΔTb) was evaluated with thermometry. ΔHb was determined via direct calorimetry and also used to calculate ΔTb.

Results: Although average rectal temperature did not exceed 38.0°C, heat balance was not achieved during exercise in any work protocol (i.e., rate of ΔTre > 0°C·min; all P values ≤ 0.02). Consequently, it was projected that if work was extended to 4 h, the distribution of participant core temperatures higher and lower than 38.0°C would be statistically similar (all P values ≥ 0.10). Furthermore, ΔHb was similar between protocols (P = 0.70). However, a greater ΔTb was observed with calorimetry relative to thermometry in WR3:1[29.0°C] (P = 0.03), WR1:1[30.0°C] (P = 0.02), and WR1:3[31.5°C] (P < 0.01) but not CON[28.0°C] (P = 0.32).

Conclusion: The current study demonstrated that heat balance was not achieved and ΔTb and ΔHb were inconsistent, suggesting that the TLV may not adequately protect workers during work in hot conditions.

We examined the separate and combined effects of plasma osmolality and baroreceptor loading status on postexercise heat loss responses. Nine young males completed a 45-min treadmill exercise protocol at 58 ± 2% V̇o2 peak, followed by a 60-min recovery. On separate days, participants received 0.9% NaCl (ISO), 3.0% NaCl (HYP), or no infusion (natural recovery) throughout exercise. In two additional sessions (no infusion), lower-body negative (LBNP) or positive (LBPP) pressure was applied throughout the final 45 min of recovery. Local sweat rate (LSR; ventilated capsule: chest, forearm, upper back, forehead) and skin blood flow (SkBF; laser-Doppler flowmetry: forearm, upper back) were continuously measured. During HYP, upper back LSR was attenuated from end-exercise to 10 min of recovery by ∼0.35 ± 0.10 mg·min(-1)·cm(-2) and during the last 20 min of recovery by ∼0.13 ± 0.03 mg·min(-1)·cm(-2), while chest LSR was lower by 0.18 ± 0.06 mg·min(-1)·cm(-2) at 50 min of recovery compared with natural recovery (all P < 0.05). Forearm and forehead LSRs were not affected by plasma hyperosmolality during HYP (all P > 0.28), which suggests regional differences in the osmotic modulation of postexercise LSR. Furthermore, LBPP application attenuated LSR by ∼0.07-0.28 mg·min(-1)·cm(-2) during the last 30 min of recovery at all sites except the forehead compared with natural recovery (all P < 0.05). Relative to natural recovery, forearm and upper back SkBF were elevated during LBPP, ISO, and HYP by ∼6-10% by the end of recovery (all P < 0.05). We conclude that 1) hyperosmolality attenuates postexercise sweating heterogeneously among skin regions, and 2) baroreceptor loading modulates postexercise SkBF independently of changes in plasma osmolality without regional differences.

We examined whether sustained changes in baroreceptor loading status during prolonged postexercise recovery can alter the metaboreceptors’ influence on heat loss. Thirteen young males performed a 1-min isometric handgrip exercise (IHG) at 60% maximal voluntary contraction followed by 2 min of forearm ischemia (to activate metaboreceptors) before and 15, 30, 45, and 60 min after a 15-min intense treadmill running exercise (>90% maximal heart rate) in the heat (35°C). This was repeated on three separate days with continuous lower body positive (LBPP, +40 mmHg), negative (LBNP, -20 mmHg), or no pressure (Control) from 13- to 65-min postexercise. Sweat rate (ventilated capsule; forearm, chest, upper back) and cutaneous vascular conductance (CVC; forearm, upper back) were measured. Relative to pre-IHG levels, sweating at all sites increased during IHG and remained elevated during ischemia at baseline and similarly at 30, 45, and 60 min postexercise (site average sweat rate increase during ischemia: Control, 0.13 ± 0.02; LBPP, 0.12 ± 0.02; LBNP, 0.15 ± 0.02 mg·min(-1)·cm(-2); all P < 0.01), but not at 15 min (all P > 0.10). LBPP and LBNP did not modulate the pattern of sweating to IHG and ischemia (all P > 0.05). At 15-min postexercise, forearm CVC was reduced from pre-IHG levels during both IHG and ischemia under LBNP only (ischemia: 3.9 ± 0.8% CVCmax; P < 0.02). Therefore, we show metaboreceptors increase postexercise sweating in the middle to late stages of recovery (30-60 min), independent of baroreceptor loading status and similarly between skin sites. In contrast, metaboreflex modulation of forearm but not upper back CVC occurs only in the early stages of recovery (15 min) and is dependent upon baroreceptor unloading.

We examined whether older individuals with and without Type 2 diabetes (T2D) experience differences in heart rate variability (HRV) during a 3-h exposure to high heat stress compared with young adults. Young (Young; n = 22; 23 ± 3 yr) and older individuals with (T2D; n = 11; 59 ± 9 yr) and without (Older; n = 25; 63 ± 5 yr) T2D were exposed to heat stress (44°C, 30% relative humidity) for 3 h. Fifty-five HRV measures were assessed for 15 min at baseline and at minutes 82.5-97.5 (Mid) and minutes 165-180 (End) during heat stress. When compared with Young, a similar number of HRV indices were significantly different (P < 0.05) in Older (Baseline: 35; Mid: 29; End: 32) and T2D (Baseline: 31; Mid: 30; End: 27). In contrast, the number of HRV indices significantly different (P < 0.05) between Older and T2D were far fewer (Baseline: 13, Mid: 1, End: 3). Within-group analyses demonstrated a greater change in the Young group’s HRV during heat stress compared with Older and T2D; the number of significantly different (P < 0.05) HRV indices between baseline and End were 42, 29, and 20, for Young, Older, and T2D, respectively. Analysis of specific HRV domains suggest that the Young group experienced greater sympathetic activity during heat stress compared with Older and T2D. In conclusion, when compared with young, older individuals with and without T2D demonstrate low HRV at baseline and less change in HRV (including an attenuated sympathetic response) during 3 h high heat stress, potentially contributing to impaired thermoregulatory function.

We developed and validated an aquaticity assessment test (AAT) for the evaluation of human physical adequacy in the water. Forty-six volunteers (25M/21F; 20 8 years) participated and performed 10 easy-to-administer and practical aquatic tasks. Group A was formed by 36 elite athletes (M/F 20/16, 24.7 10yrs) from two sports categories d epending on their affinity to the water environment: terrestrial (wrestling, cycling, dancing) and aquatic (swimming, synchronized swimming, free diving) sports. Group B was formed by 10 non-athlete participants (5M/5F, 14.4 1.4yrs) and was assessed by two independent evaluators. Participants in Group A performed the aquatic tasks once to develop the final AAT items and cutoffs. Participants in Group B per-formed the aquatic tasks twice on different days to assess repeatability. Factor analysis recom-mended all 10 aquatic tasks to be included in the final AAT, resulting in scores ranging from 9.5 to 49.5. The AAT scores were statistically different between the terrestrial and the aquatic sports’ participants (p <0.001). The duration of the test was 25 min from the time of water entry. Receiver operating characteristics curve analyses demonstrated that the cutoffs for low and high aquaticity levels in this sample were 23.7 and 43.3, respectively. Reliability analyses demon-strated that the aquaticity scores obtained on different days and by different examiners highly correlated (p <0.001) and were not significantly different (p >0.05). The AAT appears to be a valid and reliable tool for the evaluation of human physical adequacy in the water. It is an easy and user-friendly test which can be performed in any swimming pool without a need for highly trained staff and specialized equipment, however more research needs to be done in order to be applied in other population group.

Introduction: Obesity constitutes a serious global health concern reaching pandemic prevalence rates. The existence of functional brown adipose tissue (BAT) in adult humans has provoked intense research interest in the role of this metabolically active tissue in whole-body energy balance and body weight reg-ulation. A number of environmental, physiological, pathological, and pharmacological stimuli have been proposed to induce BAT-mediated thermogenesis and functional thermogenic BAT-like activity in white adipose tissue (WAT), opening new avenues for therapeutic strategies based on enhancing the number of beige adipocytes in WAT. Hypothesis: Recent evidence support a role of L-menthol cooling, mediated by TRPM8 receptor, on UCP1-dependent thermogenesis and BAT-like activity in classical WAT depots along with the recruitment of BAT at specific anatomical sites. L-Menthol-induced BAT thermogenesis has been suggested to occur by a b-adrenergic-independent mechanism, avoiding potential side-effects due to extensive b-adrenergic stimulation mediated by available beta receptor agonists. L-Menthol has been also linked to the activation of the cold-gated ion channel TRPA1. However, its role in L-menthol-induced UCP1-dependent thermo-genic activity in BAT and WAT remains undetermined. White adipose tissue plasticity has important clin-ical implications for obesity prevention and/or treatment because higher levels of UCP1-dependent thermogenesis can lead to enhanced energy expenditure at a considerable extent. We hypothesize that chronic dietary L-menthol treatment could induce TRPM8- and TRPA1-dependent WAT adaptations, resembling BAT-like activity, and overall improve whole-body metabolic health in obese and overweight individuals. Conclusions: The putative impact of chronic L-menthol dietary treatment on the stimulation of BAT-like activity in classical WAT depots in humans remains unknown. A detailed experimental design has been proposed to investigate the hypothesized L-menthol-induced browning of WAT. If our hypothesis was to be confirmed, TRPM8/TRPA1-induced metabolic adaptations of WAT to BAT-like activity could provide a promising novel therapeutic approach for increasing energy expenditure, regulating body weight, and preventing obesity and its related co-morbidities in humans.

The proportion of older workers has increased substantially in recent years, with over 25% of the Canadian labour force aged ≥55 years. Along with chronological age comes age-related declines in functional capacity associated with impair-ments to the cardiorespiratory and muscular systems. As a result, older workers are reported to exhibit reductions in work output and in the ability to perform and/or sustain the required effort when performing work tasks. However, research has presented some conflicting views on the consequences of aging in the workforce, as physically demanding occupations can be associated with improved or maintained physical function. Furthermore, the current methods for evaluating physical function in older workers often lack specificity and relevance to the actual work tasks, leading to an underestimation of physical capacity in the older worker. Nevertheless, industry often lacks the appropriate information and/or tools to accommodate the aging workforce, particularly in the context of physical employment standards. Ultimately, if appropriate workplace strategies and work performance standards are adopted to optimize the strengths and protect against the vulnerability of the aging workers, they can perform as effectively as their younger counterparts. Our aim in this review is to evaluate the impact of different individual (including physiological decline, chronic disease, lifestyle, and physical activity) and occupational (including shift work, sleep deprivation, and cold/heat exposure) factors on the physical decline of older workers, and therefore the risk of work-related injuries or illness.

Context: It has been indicated that acute active and passive tobacco cigarette smoking may cause changes on redox status balance that may result in significant pathologies. However, no study has evaluated the effects of active and passive e-cigarette smoking on redox status of consumers.

Objective: To examine the acute effects of active and passive e-cigarette and tobacco cigarette smoking on selected redox status markers.

Methods: Using a randomized single-blind crossover design, 30 participants (15 smokers and 15 nonsmokers) were exposed to three different experimental conditions. Smokers underwent a control session, an active tobacco cigarette smoking session (smoked 2 cigarettes within 30-min) and an active e-cigarette smoking session (smoked a pre-determined number of puffs within 30-min using a liquid with 11 ng/ml nicotine). Similarly, nonsmokers underwent a control session, a passive tobacco cigarette smoking session (exposure of 1 h to 23 ± 1 ppm of CO in a 60 m(3) environmental chamber) and a passive e-cigarette smoking session (exposure of 1 h to air enriched with pre- determined number of puffs in a 60 m(3) environmental chamber). Total antioxidant capacity (TAC), catalase activity (CAT) and reduced glutathione (GSH) were assessed in participants’ blood prior to, immediately after, and 1-h post-exposure.

Results: TAC, CAT and GSH remained similar to baseline levels immediately after and 1-h-post exposure (p > 0.05) in all trials.

Conclusions: Tobacco and e-cigarette smoking exposure do not acutely alter the response of the antioxidant system, neither under active nor passive smoking conditions. Overall, there is not distinction between tobacco and e-cigarette active and passive smoking effects on specific redox status indices.

In this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trial performance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trials in the heat (30C) was on average reduced by 15% in the 14 studies that fulfilled the inclusion criteria. Ambient temperature per se was a poor predictor of the integrated environmental heat stress and 2 of the prevailing heat stress indices (WBGT and UTCI) failed to predict the environmental influence on performance. The weighing of wind speed appears to be too low for predicting the effect for cycling in trained acclimatized subjects, where performance may be maintained in outdoor time trials at ambient temperatures as high as 36C (36 C UTCI; 28 C WBGT). Power output during indoor trials may also be maintained with temperatures up to at least 27C when humidity is modest and wind speed matches the movement speed generated during outdoor cycling, whereas marked reductions are observed when air movement is minimal. For running, representing an exercise mode with lower movement speed and higher heat production for a given metabolic rate, it appears that endurance is affected even at much lower ambient temperatures. On this basis we conclude that environmental heat stress impacts self-paced endurance performance. However, the effect is markedly modified by acclimatization status and exercise mode, as the wind generated by the exercise (movement speed) or the environment (natural or fan air movement) exerts a strong in fluence.

We assessed the physical demands associated with electrical utilities work in North America and how they influence the level of thermal and cardiovascular strain experienced. Three common job categories were monitored as they are normally performed in thirty-two electrical utility workers: (i) Ground Work (n = 11), (ii) Bucket Work (n = 9), and (iii) Manual Pole Work (n = 12). Video analysis was performed to determine the proportion of the work monitoring period (duration: 187 ± 104 min) spent at different levels of physical effort (i.e., rest as well as light, moderate and heavy effort). Core and skin temperatures as well as heart rate were measured continuously. On average, workers spent 35.9 ± 15.9, 36.8 ± 17.8, 24.7 ± 12.8, and 2.6 ± 3.3% of the work period at rest and performing work classified as light, moderate, and heavy physical effort, respectively. Moreover, a greater proportion of the work period was spent performing heavy work in Ground Work (1.6 ± 1.4%) relative to Bucket Work (0.0 ± 0.0%; P<0.01) and in Manual Pole Climbing (5.5 ± 3.6%) in comparison to both other work job (both P≤0.03). Furthermore, the proportion of time spent during work classified as heavy physical effort was positively correlated to the mean (r = 0.51, P<0.01) and peak (r = 0.42, P = 0.02) core temperatures achieved during the work period as well as the mean heart rate response (presented as a percentage of heart rate reserve; r = 0.40, P = 0.03). Finally, mean and peak core temperatures and mean heart rate responses increased from the first to the second half of the work shift; however, no differences in the proportion of the work spent at the different intensity classifications were observed. We show that Manual Pole Work is associated with greater levels of physical effort compared to Ground or Bucket Work. Moreover, we suggest that the proportion of time spent performing work classified as heavy physical exertion is related to the level of thermal and cardiovascular strain experienced and that workers may not be employing self-pacing as a strategy to manage their level of physiological strain.

Purpose: We evaluated core temperature responses and the change in body heat content (ΔHb) during work performed according to the ACGIH threshold limit values (TLV) for heat stress, which are designed to ensure a stable core temperature that does not exceed 38.0°C.

Methods: Nine young males performed a 120-min work protocol consisting of cycling at a fixed rate of heat production (360 W). On the basis of the TLV, each protocol consisted of a different work-rest (WR) allocation performed in different wet-bulb globe temperatures (WBGT). The first was 120 min of continuous (CON) cycling at 28.0°C WBGT (CON[28.0°C]). The remaining three protocols were intermittent work bouts (15-min duration) performed at various WR and WBGT: (i) WR of 3:1 at 29.0°C (WR3:1[29.0°C]), (ii) WR of 1:1 at 30.0°C (WR1:1[30.0°C]), and (iii) WR of 1:3 at 31.5°C (WR1:3[31.5°C]) (total exercise time: 90, 60, and 30 min, respectively). The change in rectal (ΔTre) and mean body temperature (ΔTb) was evaluated with thermometry. ΔHb was determined via direct calorimetry and also used to calculate ΔTb.

Results: Although average rectal temperature did not exceed 38.0°C, heat balance was not achieved during exercise in any work protocol (i.e., rate of ΔTre > 0°C·min; all P values ≤ 0.02). Consequently, it was projected that if work was extended to 4 h, the distribution of participant core temperatures higher and lower than 38.0°C would be statistically similar (all P values ≥ 0.10). Furthermore, ΔHb was similar between protocols (P = 0.70). However, a greater ΔTb was observed with calorimetry relative to thermometry in WR3:1[29.0°C] (P = 0.03), WR1:1[30.0°C] (P = 0.02), and WR1:3[31.5°C] (P < 0.01) but not CON[28.0°C] (P = 0.32).

Conclusion: The current study demonstrated that heat balance was not achieved and ΔTb and ΔHb were inconsistent, suggesting that the TLV may not adequately protect workers during work in hot conditions.

The aim of this study was to evaluate thermogenesis in the interscapular brown adipose tissue (IBAT) of rats submitted to low-protein, high-carbohydrate (LPHC) diet and the involvement of adrenergic stimulation in this process. Male rats (~100 g) were submitted to LPHC (6 %-protein; 74 %-carbohydrate) or control (C; 17 %-protein; 63 %-carbohydrate) isocaloric diets for 15 days. The IBAT temperature was evaluated in the rats before and after the administration of noradrenaline (NA) (20 μg 100 g b w1 min1). The expression levels of uncoupling protein 1 (UCP1) and other proteins involved in the regulation of UCP1 expression were determined by Western blot (Student’s t test, P 0.05). The LPHC diet promoted a 1.1 °C increase in the basal temperature of IBAT when compared with the basal temperature in the IBAT of the C group. NA administration promoted a 0.3 °C increase in basal temperature in the IBAT of the C rats and a 0.5 °C increase in the IBAT of the LPHC group. The level of UCP1 increased 60 % in the IBAT of LPHC-fed rats, and among the proteins involved in its expression, such as β3-AR and α1-AR, there was a 40 % increase in the levels of p38-MAPK and a 30 % decrease in CREB when compared to the C rats. The higher sympathetic flux to IBAT, which is a consequence of the administration of the LPHC diet to rats, activates thermogenesis and increases the expression of UCP1 in the tissue. Our results suggest that the increase in UCP1 content may occur via p38 MAPK and ATF2.

Purpose We examined effects of a three-game, 1-week microcycle (G1, G2, G3) on recovery of performance and inflammatory responses in professional male footballers. Methods Players were randomized into an experimental
(EXP; N = 20) and a control group (CON; N = 20). Blood was drawn and repeated sprint ability (RSA), muscle soreness and knee range of motion (KJRM) were determined pre- and post-games and during recovery. Results High-intensity running during G2 was 7–14 % less compared to G1 and G3. RSA declined in EXP by 2–9 % 3 days post-game with G2 causing the greatest performance impairment. In EXP, game play increased muscle
soreness (~sevenfold) compared to CON with G2 inducing the greatest rise, while KJRM was attenuated post-game in EXP compared to CON (5–7 %) and recovered slower post G2 and G3 than G1. CK, CRP, sVCAM-1, sP-Selectin and cortisol peaked 48 h post-games with G2 eliciting the greatest increase. Leukocyte count, testosterone, IL-1β and IL6 responses, although altered 24 h post each game, were comparable among games. Plasma TBARS and pro-tein carbonyls rose by ~50 % post-games with G2 eliciting the greatest increase 48 h of recovery. Reduced to oxidized glutathione ratio declined for 24 h post all games with G2 displaying the slowest recovery. Total antioxidant capacity and glutathione peroxidase activity increased (9–56 %) for 48 h in response to game play. Conclusion In summary, post-game performance recov-ery and inflammatory adaptations in response to a three-game weekly microcycle displayed a different response pattern, with strong indications of a largest physiological stress and fatigue after the middle game that was preceded by only a 3-day recovery.

We investigated the absorption and metabolism pharmacokinetics of a single L-menthol oral versus skin administration and the effects on human thermogenesis and metabolic rate. Twenty healthy adults were randomly distributed into oral (capsule) and skin (gel) groups and treated with 10 mg kg1 L-menthol (ORALMENT; SKIN MENT) or control (lactose capsule: ORALCON; water application: SKINCON) in a random order on two different days. Levels of serum L-menthol increased similarly in ORALMENT and SKINMENT (p > 0.05). L-menthol glucuronidation was greater in ORALMENT than SKINMENT (p < 0.05). Cutaneous vasoconstriction, rectal temperature and body heat storage showed greater increase following SKINMENT compared to ORALMENT and control conditions (p < 0.05). Metabolic rate increased from baseline by 18% in SKINMENT and 10% in ORALMENT and respiratory exchange ratio decreased more in ORALMENT (5.4%) than SKINMENT (4.8%) compared to control conditions (p < 0.05). Levels of plasma adiponectin and leptin as well as heart rate variability were similar to control following either treatment (p > 0.05). Participants reported no cold, shivering, discomfort, stress or skin irritation. We conclude that a single L-menthol skin administration increased thermogenesis and metabolic rate in humans. These effects are minor fol-lowing L-menthol oral administration probably due to faster glucuronidation and greater blood menthol glucuronide levels.

Studies have reported that older females have impaired heat loss responses during work in the heat compared to young females. However, it remains unclear at what level of heat stress these differences occur. Therefore, we examined whole-body heat loss [evaporative (HE) and dry heat loss, via direct calorimetry] and changes in body heat storage (ΔHb, via di-rect and indirect calorimetry) in 10 young (23±4 years) and 10 older (58±5 years) females matched for body surface area and aerobic fitness (VO2peak) during three 30-min exercise bouts performed at incremental rates of metabolic heat production of 250 (Ex1), 325 (Ex2) and 400 (Ex3) W in the heat (40°C, 15% relative humidity). Exercise bouts were separated by 15 min of recovery. Since dry heat gain was similar between young and older females during exercise (p=0.52) and recovery (p=0.42), differences in whole-body heat loss were solely due to HE. Our results show that older females had a significantly lower HE at the end of Ex2 (young: 383±34 W; older: 343±39 W, p=0.04) and Ex3 (young: 437±36 W; older: 389±29 W, p=0.008), however no difference was measured at the end of Ex1 (p=0.24). Also, the magnitude of difference in the maximal level of HE achieved between the young and older females became greater with increasing heat loads (Ex1=10.2%, Ex2=11.6% and Ex3=12.4%). Furthermore, a significantly greater ΔHb was measured for all heat loads for the older females (Ex1: 178±44 kJ; Ex2: 151±38 kJ; Ex3: 216±25 kJ, p=0.002) relative to the younger females (Ex1: 127±35 kJ; Ex2: 96±45 kJ; Ex3: 146±46 kJ). In contrast, no dif-ferences in HE or ΔHb were observed during recovery (p>0.05). We show that older habitu-ally active females have an impaired capacity to dissipate heat compared to young females during exercise-induced heat loads of 325 W when performed in the heat.

Aging is associated with an attenuated physiological ability to dissipate heat. However, it remains unclear if age-related impairments in heat dissipation only occur above a certain level of heat stress and whether this response is altered by aerobic fitness. Therefore, we examined changes in whole body evaporative heat loss (HE) as determined using whole body direct calorimetry in young (n = 10; 21 ± 1 yr), untrained middle-aged (n = 10; 48 ± 5 yr), and older (n = 10; 65 ± 3 yr) males matched for body surface area. We also studied a group of trained middle-aged males (n = 10; 49 ± 5 yr) matched for body surface area with all groups and for aerobic fitness with the young group. Participants performed intermittent aerobic exercise (30-min exercise bouts separated by 15-min rest) in the heat (40°C and 15% relative humidity) at progressively greater fixed rates of heat production equal to 300 (Ex1), 400 (Ex2), and 500 (Ex3) W. Results showed that HE was significantly lower in middle-aged untrained (Ex2: 426 ± 34; and Ex3: 497 ± 17 W) and older (Ex2: 424 ± 38; and Ex3: 485 ± 44 W) compared with young (Ex2: 472 ± 42; and Ex3: 558 ± 51 W) and middle-aged trained (474 ± 21; Ex3: 552 ± 23 W) males at the end of Ex2 and Ex3 (P < 0.05). No differences among groups were observed during recovery. We conclude that impairments in HE in older and middle-aged untrained males occur at exercise-induced heat loads of ≥400 W when performed in a hot environment. These impairments in untrained middle-aged males can be minimized through regular aerobic exercise training.

While the link between thermoregulation and aging is generally accepted, much further research, reflection, and debate is required to elucidate the physiological and molecular pathways that generate the observed thermal-induced changes in lifespan. Our aim in this review is to present, discuss, and scrutinize the thermoregulatory mechanisms that are implicated in the aging process in endotherms and ectotherms. Our analysis demonstrates that low body temperature benefits lifespan in both endothermic and ectothermic organisms. Research in endotherms has delved deeper into the physiological and molecular mechanisms linking body temperature and longevity. While research in ectotherms has been steadily increasing during the past decades, further mechanistic work is required in order to fully elucidate the underlying phenomena. What is abundantly clear is that both endotherms and ectotherms have a specific temperature zone at which they function optimally. This zone is defended through both physiological and behavioral means and plays a major role on organismal senescence. That low body temperature may be beneficial for lifespan is contrary to conventional medical theory where reduced body temperature is usually considered as a sign of underlying pathology. Regardless, this phenomenon has been targeted by scientists with the expectation that advancements may compress morbidity, as well as lower disease and mortality risk. The available evidence suggests that lowered body temperature may prolong life span, yet finding the key to temperature regulation remains the problem. While we are still far from a complete understanding of the mechanisms linking body temperature and longevity, we are getting closer.

The human capacity to perform prolonged exercise is impaired in hot environments. To address this issue, a number of studies have investigated behavioral aspects of thermoregulation that are recognized as important factors in determining performance. In this review, we evaluated and interpreted the available knowledge regarding the voluntary control of exercise work rate in hot environments. Our analysis indicated that: (a) Voluntary reductions in exercise work rate in uncompensable heat aid thermoregulation and are, therefore, thermoregulatory behaviors. (b) Unlike thermal behavior during rest, the role of thermal comfort as the ultimate mediator of thermal behavior during exercise in the heat remains uncertain. By contrast, the rating of perceived exertion appears to be the key perceptual controller under such conditions, with thermal perception playing a more modulatory role. (c) Prior to increases in core temperature (when only skin temperature is elevated), reductions in self-selected exercise work rate in the heat are likely mediated by thermal perception (thermal comfort and sensation) and its influence on the rating of perceived exertion. (d) However, when both core and skin temperatures are elevated, factors associated with cardiovascular strain likely dictate the rate of perceived exertion response, thereby mediating such voluntary reductions in exercise work rate.

We thank the correspondents [1] for their interest in the recent consensus statement on training and competing in the heat [2]. However, we were somewhat perplexed to note that the authors considered that the consensus statement “did not highlight one of the main current limitations: the recommendations for various sporting governing bodies (i.e., event organizers and international federations) are still based on the Wet-Bulb Globe Temperature (WBGT) index”. Indeed, one of the main recommendations in the consensus statement is that “the WBGT is an environmental heat stress index and not a representation of human heat strain. It is therefore difficult to establish absolute participation cut-off values across sports for different athletes and we rather recommend implementing preventive countermeasures or evaluating the specific demands of the sport when preparing extreme heat policies” [2].

The purpose of this study was to assess the physiological strain experienced by North American electrical utility workers during the performance of their normal work duties in heat stressed conditions. Three common job categories were monitored as they are normally performed in 32 electrical utility workers: (i) Ground Work (n = 11); (ii) Bucket Work (n = 9); and (iii) Manual Pole Work (n = 12). Worker hydration status (urine specific gravity (USG)) was measured prior to and following the work monitoring period (duration: 187 ± 104 min). Core and skin temperatures as well as heart rate were measured continuously. Physiological Strain Index (PSI) was calculated from the measurements of core temperature and heart rate. Prior to the start of the work shift, 38% of workers were euhydrated (USG < 1.020; n = 12) whereas the majority of workers were dehydrated (USG > 1.020; prevalence: 75%; p < 0.01) following work. The overall mean and peak core temperatures for all monitored workers were 37.9 ± 0.3 °C and 38.3 ± 0.5 °C, respectively. When responses were compared between job categories, greater mean and peak increases in core temperature were observed in Manual Pole Work relative to the other job categories (both p < 0.04). In fact, six workers performing Manual Pole Work achieved core temperatures in excess of 38.5 °C, while only one other worker surpassed this threshold in Bucket Work. The high levels of thermal strain were paralleled by elevated mean and peak heart rate and PSI responses, which were greater in Manual Pole Work in comparison to the other job categories (all p ≤ 0.05). Furthermore, two workers performing Manual Pole Work achieved severely elevated core temperatures reaching or exceeding 39.5 °C along with prolonged periods of near maximal heart rate responses (i.e., >90% of heart rate reserve). We report elevated levels of thermal and cardiovascular strain in electrical utility workers during work in the heat and potentially dangerous levels of hyperthermia during particularly strenuous work.

Purpose: The aging-induced reduction in whole-body heat loss (HL) capacity generates concerns regarding the continued participation of older workers in occupations such as firefighting. We compared HL and change in body heat storage (S) during intermittent exercise in warm/dry and warm/humid conditions among older male firefighters (OLDER, n = 9, age = 54.7 ± 2.1 yr), older (age-matched) nonfirefighters (NON-FF, n = 9, age = 52.8 ± 1.2 yr), and young firefighters (YOUNG, n = 6, age = 26.7 ± 0.8 yr).

Methods: We measured evaporative heat loss and dry heat exchange via the Snellen whole-body direct calorimeter while participants performed four 15-min bouts of cycling at 400 W of metabolic heat production separated by 15-min recovery periods in warm/dry (35 °C, 20% relative humidity) and warm/humid (35 °C, 60% relative humidity) conditions.

Results: We found no differences (P > 0.05) in HL or cumulative S (ΔS) between OLDER and NON-FF in the warm/dry (ΔS: OLDER = 233 ± 26 kJ, NON-FF = 270 ± 29 kJ) or warm/humid (ΔS: OLDER = 548 ± 24 kJ, NON-FF = 504 ± 47 kJ) conditions. The OLDER and NON-FF had lower HL than the YOUNG during exercise in both environmental conditions (P < 0.05). The OLDER stored 40% (P > 0.05) and 46% (P = 0.004) more heat than YOUNG in the warm/dry and warm/humid conditions, respectively. The NON-FF stored 63% (P = 0.016) and 34% (P = 0.025) more heat than the YOUNG in the dry and humid conditions, respectively.

Conclusions: Older firefighters and age-matched nonfirefighters demonstrate similar HL and S during work in the heat. Moreover, HL is significantly reduced in older compared to younger firefighters during exercise in both warm/dry and warm/humid conditions. Consequently, older firefighters may be more susceptible to thermal injury while on duty than their younger counterparts.

We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12 h, 36 h and 60 h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12 h, 36 h and 60 h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60 h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12 h (both limbs) and 36 h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36 h at 60°/s and for 60 h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes’ football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players’ physical conditioning level.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimise performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimise performance is to heat acclimatise. Heat acclimatisation should comprise repeated exercise-heat exposures over 1–2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimise dehydration during exercise. Following the development of commercial cooling systems (eg, cooling-vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organisers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimising the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events, for hydration and body cooling opportunities, when competitions are held in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimise performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimise performance is to heat acclimatise. Heat acclimatisation should comprise repeated exercise-heat exposures over 1–2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimise dehydration during exercise. Following the development of commercial cooling systems (eg, cooling-vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organisers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimising the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events, for hydration and body cooling opportunities, when competitions are held in the heat.

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consen-sus statement is to provide up-to-date recommendations to optimize performance during sporting activities under-taken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise-heat exposures over 1–2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vest), athletes can implement cooling strategies to facili-tate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event orga- nizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competi-tions are held in the heat.

Dear Editor-in-Chief,

The paper by Kobayashi entitled “Temperature receptors in cutaneous nerve endings are thermostat molecules that induce thermoregulatory behaviors against thermal load”1 summarizes a series of elegant studies conducted by Kobayashi and colleagues during the past 30 years. These studies have challenged the “hypothalamic proportional control” model which remains the most widely accepted approach for the functional architecture of endothermic thermoregulation over the past 50+ years.2 Kobayashi opposes the dogma that receptors are sensors, arguing instead that receptors are “comparators.”1 He proposes that heat- and cold-sensitive neurons are comparators of temperature and evoke impulses when temperature surpasses a receptor activation threshold. In turn, these impulses are not a form of neural code (as assumed by the “hypothalamic proportional control” model) but they are actually triggers to activate target effector neurons in the brain. For instance, when skin temperature is below its threshold value, peripheral cold-sensitive neurons evoke impulses to stimulate target neurons in the brain responsible for appropriate heat-seeking responses. Consequently, skin coolness “…only occurs in the sensation world in our mind.”3 Ergo, the “comparator” model suggests that effectors are triggered via sensory neurons directly, without the involvement/presence of a separate decision-making network or temperature code computations.

Stretching exercises to increase the range of motion (ROM) of joints have been used by sports coaches and medical professionals for improving performance and rehabilitation. The ability of connective and muscular tissues to change their architecture in response to stretching is important for their proper function, repair, and performance. Given the dearth of relevant data in the literature, this review examined two key elements of stretching: stretch intensity and stretch position; and their significance to ROM, delayed onset muscle soreness (DOMS), and inflammation in different populations. A search of three databases, Pub-Med, Google Scholar, and Cochrane Reviews, identified 152 articles, which were subsequently categorized into four groups: athletes (24), clinical (29), elderly (12), and general population (87). The use of different populations facilitated a wider examination of the stretching components and their effects. All 152 articles incorporated information regarding duration, frequency and stretch position, whereas only 79 referred to the intensity of stretching and 22 of these 79 studies were deemed high quality. It appears that the intensity of stretching is relatively under-researched, and the importance of body position and its influence on stretch intensity, is largely unknown. In conclusion, this review has highlighted areas for future research, including stretch intensity and position and their effect on musculo-tendinous tissue, in relation to the sensation of pain, delayed onset muscle soreness, inflammation, as well as muscle health and performance.

Background and objective: While some authors report that dancers have reduced bone mineral density (BMD) and increased risk of osteoporosis, others have stressed the positive effects of dance training on developing healthy BMD. Given the existing controversy, the aim of this systematic review was to examine the best evidence-based information available in relation to female dancers.

Methods: Four databases (Web of Science, PubMed, EBSCO, Scopus) and two dance science journals (Journal of Dance Medicine and Science and Medical Problems of Performing Artists) were searched for relevant material using the keywords “dance”, “ballet”, “BMD”, “bone density”, “osteoporosis” and “female athlete triad syndrome”. A total of 257 abstracts were screened using selected inclusion (studies involving bone measurements in dancers) and exclusion (editorials, opinion papers, chapters in books, narrative reviews and non-English language papers) criteria according to PRISMA guidelines. Following the above screening, a total of 108 abstracts were identified as potentially relevant. After the exclusion of conference proceedings, review papers, studies focusing only in male dancers and studies in which dancers’ information were combined with other athletes, the eligible papers were subsequently assessed using the GRADE system and grouped according to: (1) prevalence of low BMD and associated factors, (2) incidence of low BMD and risk factors, (3) prevention/treatment of low BMD in dancers, and (4) other studies.

Results: Of the 257 abstracts that were initially screened, only 35 studies were finally considered. Only one of these 35 was of high quality, while the remaining 34 were of relatively low quality. Seven studies reported prevalence of low BMD and associated factors, 10 reported associated factors with no prevalence data, while one reported prevalence with no associated factors data. One study cited risk factors, while another one elaborated on the treatment of low BMD in dancers. The remaining 15 studies were classified as “other studies”.

Conclusions: It remains unclear whether low BMD is prevalent in female dancers. The present review highlights the need for high-quality BMD research in this area.

Immediate treatment with cold water immersion (CWI) is the gold standard for exertional heatstroke. In the field, however, treatment is often delayed due to delayed para-medic response and/or inaccurate diagnosis. We exam-ined the effect of treatment (reduction of rectal temperature to 37.5 °C) delays of 5, 20, and 40 min on core cooling rates in eight exertionally heat-stressed (40.0 °C rectal temperature) individuals. We found that rectal temperature was elevated above baseline (P< 0.05) at the end of all delay periods (5 min: 40.08 ± 0.32; 20 min: 39.92 ± 0.40; 40 min: 39.57 ± 0.29 °C). Mean arterial pressure was reduced (P< 0.05) below baseline (92 ± 1.8 mm Hg) after all delay periods (5 min: 75 ± 2.6; 20 min: 74 ± 1.7; 40 min: 70 ± 2.1 mm Hg; P> 0.05). Rectal core cooling rates were similar among conditions (5 min: 0.20 ± 0.01; 20 min: 0.17 ± 0.02; 40 min: 0.17 ± 0.01 °C/min; P> 0.05). The rectal temperature afterdrop following CWI was similar across conditions (5 min: 35.95; 20 min: 35.61; 40 min: 35.87 °C; P> 0.05). We conclude that the effectiveness of 2 °C CWI as a treat-ment for exertional heat stress remains high even when applied with a delay of 40 min. Therefore, our results support that CWI is the most appropriate treatment for exertional heatstroke as it is capable of quickly reversing hyperthermia even when treatment is commenced with a significant delay.

We introduced noninvasive and accurate techniques to estimate muscle temperature (Tm) of vastus lateralis (VL), triceps brachii (TB), and trapezius (TRAP) during rest, exercise, and postexercise recovery using the insulation disk (iDISK) technique. Thirty-six volunteers (24 men, 12 women; 73.0 ± 12.2 kg; 1.75 ± 0.07 m; 24.4 ± 5.5 yr; 49.2 ± 6.8 ml·kg(-1)·min(-1) peak oxygen uptake) underwent periods of rest, cycling exercise at 40% of peak oxygen uptake, and postexercise recovery in three environments: Normal (24°C, 56% relative humidity), Hot-Humid (30°C, 60% relative humidity), and Hot-Dry (40°C, 24% relative humidity). Participants were randomly allocated into the “model” and the “validation” groups. Results in the model group demonstrated that Tm (VL: 36.65 ± 1.27°C; TB: 35.76 ± 1.73°C; TRAP: 36.53 ± 0.96°C) was increased compared with iDISK (VL: 35.67 ± 1.71°C; TB: 34.77 ± 2.27°C; TRAP: 35.98 ± 1.34°C) across all environments (P < 0.001). Stepwise regression analysis generated models that accurately predicted Tm (predTm) of VL (R(2) = 0.73-0.91), TB (R(2) = 0.85-0.93), and TRAP (R(2) = 0.84-0.86) using iDISK and the difference between the current iDISK temperature and that recorded between 1 and 4 min before. Cross-validation analyses in the validation group demonstrated small differences (P < 0.05) of no physiological significance, small effect size of the differences, and strong associations (r = 0.85-0.97; P < 0.001) between Tm and predTm. Moreover, narrow 95% limits of agreement and low percent coefficient of variation were observed between Tm and predTm. It is concluded that the developed noninvasive, practical, and inexpensive techniques provide accurate estimations of VL, TB, and TRAP Tm during rest, cycling exercise, and postexercise recovery.

We examined the temporal variation of iron’s status markers during a 60 h period following a football game. Thirty-four male football players were randomly assigned to a control group (CG, N = 14, participated only in measurements and training) or an experimental group (EG, N = 20, took part in a football game one week after the completion of the competitive season). All participants trained regularly for two consecutive days after the game. Training and game load was monitored with high time-resolution global positioning system (GPS) devices. Blood samples were collected and muscle damage markers and repeated sprint ability (RSA) were assessed pre-game and at 2 h, 12 h 36 h and 60 h post-game. No changes were noted in CG. Iron concentration decreased (P < 0.05) 2 h post-game and normalised thereafter whereas total iron binding capacity increased (P < 0.05) 12-60 h of recovery (P < 0.05). Erythrocytes, haemoglobin (HGB) concentration, plasma volume, haematocrit, mean cell volume, mean cell HGB, mean cell HGB concentration, red cell width-SD, red cell width-CV, ferritin concentration and transferrin saturation remained unaltered during the intervention period. Creatine kinase activity and muscle soreness increased (P < 0.05) throughout recovery in EG. RSA declined (P < 0.05) until 36 h of recovery and normalised thereafter. Our data demonstrate that iron status markers are only transiently affected by a football game.

The thermal effects related to wearing headgear are complex and different studies have investigated single parts of this topic. This review aims at summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of this review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. However, the head is among the most sensitive body parts related to thermal comfort, thereby directly affecting the willingness to wear headgear. Several methods have been used to study thermal aspects of headgear, which could be categorized as (i) numerical, (ii) biophysical, (iii) combined numerical and biophysical, and (iv) user trials. The application of these methods established that heat transfer mainly takes place through radiation and convection. Headgear parameters relevant to these heat transfer pathways, are reviewed and suggestions are provided for improving existing headgear concepts and developing new concepts, ultimately leading to more accepted headgear.

An increase in energy intake and/or a decrease in energy expenditure lead to fat storage, causing overweight and obesity phenotypes. The objective of this review was to analyse, for the first time using a systematic approach, all published evidence from the past 8 years regarding the molecular pathways linking non-shivering thermogenesis and obesity in mammals, focusing on mechanisms involved in brown adipose tissue development. Two major databases were scanned from 2006 to 2013 using ‘brown adipose tissue’ AND ‘uncoupling protein-1’ AND ‘mammalian thermoregulation’ AND ‘obesity’ as key words. A total of 61 articles were retrieved using the search criteria. The available research used knockout methodologies, various substances, molecules and agonist treatments, or different temperature and diet conditions, to assess the molecular pathways linking non-shivering thermogenesis and obesity. By integrating the results of the evaluated animal and human studies, our analysis identified specific molecules that enhance non-shivering thermogenesis and metabolism by: (i) stimulating ‘brite’ (brown-like) cell development in white adipose tissue; (ii) increasing uncoupling protein-1 expression in brite adipocytes; and (iii) augmenting brown and/or brite adipose tissue mass. The latter can be also increased through low temperature, hibernation and/or molecules involved in brown adipocyte differentiation. Cold stimuli and/or certain molecules activate uncoupling protein-1 in the existing brown adipocytes, thus increasing total energy expenditure by a magnitude proportional to the number of available brown adipocytes. Future research should address the interplay between body mass, brown adipose tissue mass, as well as the main molecules involved in brite cell development.

Objective: Augmented brown adipose tissue (BAT) mass and activity lead to higher basic metabolic rate which is beneficial against obesity. Our aim was to investigate whether habitual (i.e. usual weekly participation) physical activity is linked with BAT activity and mass in humans, in a group of patients undergoing 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scanning.

Design: Cross-sectional study.

Patients: Forty patients with cancer [26 male; 14 female; age 52·7 ± 17·5; body mass index (BMI) 26·4 ± 4·5].

Measurements: Patients completed the ‘usual week’ form of the International Physical Activity Questionnaire and underwent assessment of BAT activity/mass via 18F-fluorodeoxyglucose PET/CT.

Results: We detected a significant association between habitual physical activity (METs-minute/week) and BAT activity [normalized by body weight (BW) (τ = 0·28, P = 0·02), body surface area (BSA) (τ = 0·29, P = 0·02) and lean body mass (LBM) (τ = 0·38, P = 0·002)]. We also found a significant negative relationship between BMI and BAT activity [normalized by BW (τ = −0·30, P = 0·006), BSA (τ = −0·31, P = 0·004) and LBM (τ = −0·45, P = 0·001)] as well as a significant negative relationship between age and BAT activity [normalized by LBM (τ = −0·28, P = 0·01)]. The results also indicate significant differences between low/moderate/high levels of habitual physical activity and BAT activity (P < 0·05). Moreover, BAT activity was different across the BMI categories (normal/overweight/obese) in both sexes (P < 0·05). Finally, BAT activity was greater in women than in men (P < 0·05).

Conclusions: Increased participation in habitual physical activity is associated with higher BAT activity. Moreover, individuals with normal BMI demonstrate higher BAT activity compared to overweight and obese individuals. Finally, age is inversely linked with BAT activity, while women demonstrate higher BAT activity than men.

Developing a unifying theory for the functional architecture of endothermic thermoregulation has been proven to be a challenging endeavor. Three papers published in this issue of Temperature take a closer look at this problem and add interesting views to our knowledge about the way that endothermic thermoregulation works.

Heat waves are the cause of many preventable deaths around the world, especially among older adults and in countries with more temperate climates. In the present study, we examined the effects of age on whole-body heat loss and heat storage during passive exposure to environmental conditions representative of the upper temperature extremes experienced in Canada. Direct and indirect calorimetry measured whole-body evaporative heat loss and dry heat exchange, as well as the change in body heat content. Twelve younger (21 ± 3 years) and 12 older (65 ± 5 years) adults with similar body weight (younger: 72.0 ± 4.4 kg; older: 80.1 ± 4.2 kg) and body surface area (younger: 1.8 ± 0.1 m2; older: 2.0 ± 0.1 m2) rested for 2 h in a hot–dry [36.5 °C, 20% relative humidity (RH)] or hot–humid (36.5 °C, 60% RH) environment. In both conditions, evaporative heat loss was not significantly different between groups (dry: p = 0.758; humid: p = 0.814). However, the rate of dry heat gain was significantly greater (by approx. 10 W) for older adults relative to younger adults during the hot–dry (p = 0.032) and hot–humid exposure (p = 0.019). Consequently, the cumulative change in body heat content after 2 h of rest was significantly greater in older adults in the hot–dry (older: 212 ± 25 kJ; younger: 131 ± 27 kJ, p = 0.018) as well as the hot–humid condition (older: 426 ± 37 kJ; younger: 317 ± 45 kJ, p = 0.037). These findings demonstrate that older individuals store more heat during short exposures to dry and humid heat, suggesting that they may experience increased levels of thermal strain in such conditions than people of younger age.

The objectives of this study were to: (i) to develop questionnaires that can identify never-smoking children and adults experiencing increased exposure to secondhand smoke (SHS+), (ii) to determine their validity against hair nicotine, and (iii) assess their reliability. A sample of 191 children (85 males; 106 females; 7–18 years) and 95 adult (23 males; 72 females; 18–62 years) never-smokers consented to hair nicotine analysis and answered a large number of questions assessing all sources of SHS. A randomly-selected 30% answered the questions again after 20–30 days. Prevalence of SHS+ in children and adults was 0.52±0.07 and 0.67±0.10, respectively (p<0.05). The Smoke Scale for Children (SS-C) and the Smoke Scale for Adults (SS-A) were developed via factor analysis and included nine questions each. Positivity criteria for SS-C and SS-A via receiver operating characteristics curve analysis were identified at >16.5 and >16, respectively. Significant Kappa agreement (p<0.05) was confirmed when comparing the SS-C and SS-A to hair nicotine concentration. Reliability analyses demonstrated that the SS-C and SS-A scores obtained on two different days are highly correlated (p<0.001) and not significantly different (p>0.05). Area under the curve and McNemar’s Chi-square showed no pair-wise differences in sensitivity and specificity at the cutoff point between the two different days for SS-C and SS-A (p>0.05). We conclude that the SS-C and the SS-A represent valid, reliable, practical, and inexpensive instruments to identify children and adult never-smokers exposed to increased SHS. Future research should aim to further increase the validity of the two questionnaires.

An overview of the physiology of human thermoregulation is presented, including a discussion of the principle of heat balance and the various heat exchange pathways together with physiological adaptations during thermal challenges. Thermoeffector responses (i.e., eccrine sweating, cutaneous vasodilation) during heat stress are examined, as well as the thermoregulatory mechanisms activated during passive heat/cold stress, exercise, and postexercise, such as shivering and nonshivering thermogenesis. Aspects related to nonthermal modulators of thermoeffector responses are explored and the effects of body composition, aerobic fitness, heat acclimation, sex, age, chronic disease (i.e., diabetes), hydration, and cardiovascular function on the body’s capacity to dissipate heat are discussed.

Purpose: We examined whether treatment for exertional heat stress via ice water immersion (IWI) or natural recovery is affected by the intensity of physical work performed and, thus, the time taken to reach hyperthermia.

Methods: Nine adults (18-45 years; 17.9 ± 2.8 percent body fat; 57.0 ± 2.0 mL kg(-1) min(-1) peak oxygen uptake) completed four conditions incorporating either walking or jogging at 40 °C (20 % relative humidity) while wearing a non-permeable rain poncho. Upon reaching 39.5 °C rectal temperature (Tre), participants recovered either via IWI in 2 °C water or via natural recovery (seated in a ~29 °C environment) until T re returned to 38 °C.

Results: Cooling rates were greater in the IWI [Tre: 0.24 °C min(-1); esophageal temperature (Tes): 0.24 °C min(-1)] than the natural recovery (Tre and Tes: 0.03 °C min(-1)) conditions (p < 0.001) with no differences between the two moderate and the two low intensity conditions (p > 0.05). Cooling rates for T re and T es were greater in the 39.0-38.5 °C (Tre: 0.19 °C min(-1); Tes: 0.31 °C min(-1)) compared with the 39.5-39.0 °C (Tre: 0.11 °C min(-1); Tes: 0.13 °C min(-1)) period across conditions (p < 0.05). Similar reductions in heart rate and mean arterial pressure were observed during recovery across conditions (p > 0.05), albeit occurred faster during IWI. Percent change in plasma volume at the end of natural recovery and IWI was 5.96 and 9.58%, respectively (p < 0.001).

Conclusion: The intensity of physical work performed and, thus, the time taken to reach hyperthermia does not affect the effectiveness of either IWI treatment or natural recovery. Therefore, while the path to hyperthermia may be different for each patient, the path to recovery must always be immediate IWI treatment.

Purpose: We assessed the efficacy of different treatments (i.e., treatment with ice water immersion vs. natural recovery) and the effect of exercise intensities (i.e., low vs. high) for restoring heart rate variability (HRV) indices during recovery from exertional heat stress (EHS).

Methods: Nine healthy adults (26 ± 3 years, 174.2 ± 3.8 cm, 74.6 ± 4.3 kg, 17.9 ± 2.8 % body fat, 57 ± 2 mL·kg·(-1) min(-1) peak oxygen uptake) completed four EHS sessions incorporating either walking (4.0-4.5 km·h(-1), 2 % incline) or jogging (~7.0 km·h(-1), 2 % incline) on a treadmill in a hot-dry environment (40 °C, 20-30 % relative humidity) while wearing a non-permeable rain poncho for a slow or fast rate of rectal temperature (T re) increase, respectively. Upon reaching a T re of 39.5 °C, participants recovered until T re returned to 38 °C either passively or with whole-body immersion in 2 °C water. A comprehensive panel of 93 HRV measures were computed from the time, frequency, time-frequency, scale-invariant, entropy and non-linear domains.

Results: Exertional heat stress significantly affected 60/93 HRV measures analysed. Analyses during recovery demonstrated that there were no significant differences between HRV measures that had been influenced by EHS at the end of passive recovery vs. whole-body cooling treatment (p > 0.05). Nevertheless, the cooling treatment required statistically significantly less time to reduce T re (p < 0.001).

Conclusions: While EHS has a marked effect on autonomic nervous system modulation and whole-body immersion in 2 °C water results in faster cooling, there were no observed differences in restoration of autonomic heart rate modulation as measured by HRV indices with whole-body cold-water immersion compared to passive recovery in thermoneutral conditions.

Purpose: We evaluated the changes in core temperature, heart rate, and heart rate variability (HRV) during the induction and decay of heat acclimation.

Methods: Ten males (23 ± 3 years; 79.5 ± 3.5 kg; 15.2 ± 4.5 percent body fat; 51.13 ± 4.61 mLO(2)∙kg(-1)∙min(-1) peak oxygen uptake) underwent a 14-day heat acclimation protocol comprising of 90-min cycling at ~50 % peak oxygen uptake at 40 °C and ~20 % relative humidity. Core temperature, heart rate, and 102 HRV measures were recorded during a heat tolerance test conducted at baseline (day 0) and at the end of the induction (day 14) and decay (day 28) phases.

Results: Heat acclimation resulted in significantly reduced core temperature [rectal (χ (2) = 1298.14, p < 0.001); esophageal (χ (2) = 1069.88, p < 0.001)] and heart rate (χ (2) = 1230.17, p < 0.001). Following the decay phase, 26, 40, and 60 % of the heat acclimation-induced reductions in rectal temperature, esophageal temperature, and heart rate, respectively, were lost. Heat acclimation was accompanied by profound and broad changes in HRV: at the end of the induction phase, 75 of the 102 variability measures computed were significantly different (p < 0.001), compared to only 47 of the 102 at the end of the decay phase.

Conclusions: Heat acclimation is accompanied by reduced core temperature, significant bradycardia, and marked alterations in HRV, which we interpret as being related to vagal dominance. The observed changes in core temperature persist for at least 2 weeks of non-exposure to heat, while the changes in heart rate and HRV decay faster and are only partly evident after 2 weeks of non-exposure to heat.

We assessed the acute effects of a 1-h exposure to second-hand smoke (SHS) on complete blood count (CBC) markers in a controlled simulated bar/restaurant environment. Nineteen adult never-smokers completed a 1-h .exposure to SHS at bar/restaurant levels, and a 1-h exposure to normal room air. Blood samples were collected at the baseline at 30 min during each exposure, and at 0, 0.5, 1, 2, 3, and 4 h after each exposure. The values of white blood cells (WBC) at 1 h (p = 0.010), 3 h (p = 0.040), and 4 h (p = 0.008) following SHS were significantly increased compared with the baseline values. Also, there was a positive association between the WBC and cotinine levels (r = 0.28, p = 0.007). A 1-h exposure to SHS at bar/restaurant levels significantly increased the WBC for at least 4 h following the exposure time. This effect of SHS on WBC has dose-response characteristics and should be considered to prescribing CBC.

Recent trials demonstrated that a single brief exposure to secondhand smoke (SHS) generates acute adverse health effects. We evaluated the acute (immediately after exposure) and short-term (0.5, 1, 2, 3 and 4 h after exposure) effects of SHS on cardiac autonomic control and myocardial integrity. Nineteen adult healthy never-smokers underwent a 1 h exposure to SHS at bar/restaurant levels and a 1 h control exposure. Heart rate variability (HRV), serum cotinine, and six cardiac protein markers were assessed before, during, and up to four hours following each exposure. SHS reduced the standard deviation of normal-to-normal intervals and increased cotinine levels, creatine kinase (CK)-MB, and myoglobin (p < 0.05). We conclude that acute exposure to SHS suppresses HRV and augments CK-MB and myoglobin. The SHS-induced elevations in CK-MB and myoglobin may reflect a generalized lytic state, especially of the cardiac muscle, which is apparent for at least 2 h following the SHS exposure.

Colostrum is the first milk produced by mammalian mothers and is essential for the health and survival of the newborn. Bovine colostrum (BC) has greater concentrations of the bioactive components (i.e. immune and growth factors) than those found in human colostrum. As a result, BC supplementation has been recently adopted by many sport competitors as a means of enhancing immune function as well as improving performance. Improvements in physical performance associated with BC supplementation may stem from the ability of BC to maintain gastrointestinal (GI) integrity by decreasing GI permeability. During exercise in the heat, blood flow to the GI tract is reduced that leads to endotoxin leakage into circulation. Endotoxins, such as lipopolysaccharide, can trigger an inflammatory cascade leading to physiological strain that, in turn, increases heat storage and decreases time to exhaustion. GI permeability is lessened during passive heat stress following BC supplementation, but the influence of BC supplementation on GI function during exercise heat stress remains to be determined. The implications of endotoxemia during exercise in the heat is a matter of growing importance and warrants further study given the global increase in ambient temperatures during sport competitions.

Previous studies have shown that secondhand smoke induces lung function impairment and increases proinflammatory cytokines. The aim of the present study was to evaluate the acute effects of secondhand smoke on airway acidification and airway oxidative stress in never-smokers. In a randomized controlled cross-over trial, 18 young healthy never-smokers were assessed at baseline and 0, 30, 60, 120, 180 and 240 min after one-hour secondhand smoke exposure at bar/restaurant levels. Exhaled NO and CO measurements, exhaled breath condensate collection (for pH, H(2)O(2) and NO(2)(-)/NO(3)(-) measurements) and spirometry were performed at all time-points. Secondhand smoke exposure induced increases in serum cotinine and exhaled CO that persisted until 240 min. Exhaled breath condensate pH decreased immediately after exposure (p < 0.001) and returned to baseline by 180 min, whereas H(2)O(2) increased at 120 min and remained increased at 240 min (p = 0.001). No changes in exhaled NO and NO(2)/NO(3) were observed, while decreases in FEV(1) (p < 0.001) and FEV(1)/FVC (p < 0.001) were observed after exposure and returned to baseline by 180 min. A 1-h exposure to secondhand smoke induced airway acidification and increased airway oxidative stress, accompanied by significant impairment of lung function. Despite the reversal in EBC pH and lung function, airway oxidative stress remained increased 4 h after the exposure. Clinical trial registration number (EudraCT): 2009-013545-28.

Milk provides a rich source of macro- and micro-nutrients, and other more original compounds, the value of which is significant from a nutritional as well as a physiological perspective. Milk proteins have an increased nutritional value that is widely recognised and in many countries dairy products contribute significantly to daily protein intake. The biodefensive properties of mammalian milk proteins as well as the unique biological activities associated with each of them have been widely acknowledged for many years. These aspects are important for the use of milk proteins and milk-protein-derived peptides in dietary and pharmaceutical applications, respectively. Moreover, proteins and peptides influence various health conditions and exert regulatory functions in the human organism. Immunoglobulins are a well-known example of bioactive milk proteins, as they offer an excellent natural defence system to the neonate against bacterial infections. Overall, a large range of bioactivities have been reported for the bioactive compounds contained in milk.Our aim in this Special Issue is to explore in detail the bioactive compounds of milk and to identify their potential health effects.

Background: Heart rate variability (HRV) indices (LF, HF, LF/HF, RMSSD, and pNN50) under combined heat and orthostatic stress leading up to and during accidental syncope (EXP group: one man, two women; age: 23.7 +/- 2.9 yr) were compared with data collected from subjects who did not experience syncope (CON group: one man, two women; age: 22.3 +/- 1.5 yr).

Methods: Minute averages of HRV indices were collected during 5 min at baseline (Base), 5 min leading up to syncope (PRE), and 5 min during syncope (Syncope) (i.e., 2 min leading up to, 1 min during, and 2 min post-syncope). Data were individually analyzed as 1-min means during Syncope as well as 5-min means during Base, PRE, and Syncope.

Results: Between-group results revealed that LF and LF/HF were significantly higher and HF was significantly lower in EXP compared to CON subjects at minutes 1, 2, and 3 during Syncope. Further, RMSSD (CON: 161.1 +/- 37.0 ms; EXP: 17.5 +/- 13.3 ms) and pNN50 (CON: 26.4 +/- 36.3%; EXP: 1.3 +/- 1.2%) were significantly lower in EXP compared to CON subjects at minute 3 during Syncope. During Syncope, 5-min averages of LF (CON: 46.1 +/- 13.9 nu; EXP: 77.5 +/- 6.6 nu) and LF/HF (CON: 1.0 0.5; EXP: 3.8 +/- 1.7) were significantly higher, and HF (CON: 53.9 +/- 13.9 nu; EXP: 22.5 +/ 1 6.6 nu) was significantly lower in EXP subjects compared to CON.

Discussion: Our findings show that autonomic nervous system modulation leading up to and during accidental syncope induced by heat and orthostatic stress is characterized by an exaggerated suppression of parasympathetic and elevation of sympathetic activity. Thus, elevated LF and LF/HF, and lower HF, RMSSD, and pNN50 may represent risk factors for accidental syncope.

Context: Electronic cigarettes (e-cigarettes) are becoming increasingly popular yet their effects on health remain unknown.

Objective: To conduct the first comprehensive and standardized assessment of the acute impact of active and passive e-cigarette smoking on serum cotinine and lung function, as compared to active and passive tobacco cigarette smoking.

Materials and methods: Fifteen smokers (≥15 cigarettes/day; seven females; eight males) and 15 never-smokers (seven females; eight males) completed this repeated-measures controlled study. Smokers underwent a control session, an active tobacco cigarette (their favorite brand) smoking session and an active e-cigarette smoking session. Never-smokers underwent a control session, a passive tobacco cigarette smoking session and a passive e-cigarette smoking session. Serum cotinine, lung function, exhaled carbon monoxide and nitric oxide were assessed. The level of significance was set at p ≤ 0.001 to adjust for multiple comparisons.

Results: e-Cigarettes and tobacco cigarettes generated similar (p > 0.001) effects on serum cotinine levels after active (60.6 ± 34.3 versus 61.3 ± 36.6 ng/ml) and passive (2.4 ± 0.9 versus 2.6 ± 0.6 ng/ml) smoking. Neither a brief session of active e-cigarette smoking (indicative: 3% reduction in FEV1/FVC) nor a 1 h passive e-cigarette smoking (indicative: 2.3% reduction in FEV1/FVC) significantly affected the lung function (p > 0.001). In contrast, active (indicative: 7.2% reduction in FEV1/FVC; p < 0.001) but not passive (indicative: 3.4% reduction in FEV1/FVC; p = 0.005) tobacco cigarette smoking undermined lung function.

Conclusion: Regarding short-term usage, the studied e-cigarettes generate smaller changes in lung function but similar nicotinergic impact to tobacco cigarettes. Future research should target the health effects of long-term e-cigarette usage, including the effects of nicotine dosage.

Given the widespread incidence of smoking as well as its deleterious health effects, it is crucial to examine practical and cost effective prognostic markers assessing its health impact. Heart rate variability (HRV) is a straightforward and cost effective technique to foresee health problems of cardiovascular nature and may be used to predict in advance smoking-induced health effects. In this review we evaluate the existing biological evidence regarding the effects of smoking on HRV and their associated cardiovascular consequences. In addition, we summarize fundamental information on the various HRV indicators and their diagnostic significance in relation to heart failure. An in depth analysis of the various HRV indices characterizing changes in the activation of the autonomic nervous system is provided together with a critical evaluation of all evidence published to date on the influence of chronic and acute active and passive smoking on HRV. Overall, the vast majority of published evidence suggests that acute and chronic active and passive smoking generate marked disruptions in the normal autonomic nervous system functioning characterized by increased sympathetic drive and reduced HRV and parasympathetic modulation. The proposed mechanisms that may generate this smoke-induced HRV reduction as well as its clinical implications are thoroughly evaluated.

The objectives of this study were to: (i) to develop questionnaires that can identify never-smoking children and adults experiencing increased exposure to secondhand smoke (SHS+), (ii) to determine their validity against hair nicotine, and (iii) assess their reliability. A sample of 191 children (85 males; 106 females; 7–18 years) and 95 adult (23 males; 72 females; 18–62 years) never-smokers consented to hair nicotine analysis and answered a large number of questions assessing all sources of SHS. A randomly-selected 30% answered the questions again after 20–30 days. Prevalence of SHS+ in children and adults was 0.52±0.07 and 0.67±0.10, respectively (p<0.05). The Smoke Scale for Children (SS-C) and the Smoke Scale for Adults (SS-A) were developed via factor analysis and included nine questions each. Positivity criteria for SS-C and SS-A via receiver operating characteristics curve analysis were identified at >16.5 and >16, respectively. Significant Kappa agreement (p<0.05) was confirmed when comparing the SS-C and SS-A to hair nicotine concentration. Reliability analyses demonstrated that the SS-C and SS-A scores obtained on two different days are highly correlated (p<0.001) and not significantly different (p>0.05). Area under the curve and McNemar’s Chi-square showed no pair-wise differences in sensitivity and specificity at the cutoff point between the two different days for SS-C and SS-A (p>0.05). We conclude that the SS-C and the SS-A represent valid, reliable, practical, and inexpensive instruments to identify children and adult never-smokers exposed to increased SHS. Future research should aim to further increase the validity of the two questionnaires.

The modulation of sub-maximal voluntary exercise intensity during heat stress has been suggested as a behavioral response to maintain homeostasis; however, the relationship between thermophysiological cues and the associated response remains unclear. Awareness of an environmental manipulation may influence anticipatory planning before the start of exercise, making it difficult to isolate the dynamic integration of thermophysiological afferents during exercise itself. The purpose of the present study was to examine the direct real-time relationship between thermophysiological afferents and the behavioral response of voluntary exercise intensity. Participants were tasked with cycling at a constant rating of perceived exertion while ambient temperature (Ta) was covertly changed from 20 °C to 35 °C and then back to 20 °C at 20-minute intervals. Overall, power output (PO) and heat storage, quantified using repeated measures ANOVA, changed significantly over 20-minute intervals (135 ± 39 W, 133 ± 46 W, 120 ± 45 W; 52.35 ± 36.15 W·m− 2, 66.34 ± 22.02 W·m− 2, − 66.53 ± 56.01 W·m− 2). The synchronicity of PO fluctuations with changes in thermophysiological status was quantified using Auto-Regressive Integrated Moving Average (ARIMA) time series analysis. Fluctuations in PO were not synchronized in real time with changes in Ta; heat storage; rectal, skin, or mean body temperature; or sweat rate (stationary-r2 ≤ 0.10 and Ljung–Box statistic > 0.05 for all variables). We conclude that, while the thermal environment affects physiological responses and voluntary power output while cycling at a constant perceived effort, the behavioral response of voluntary exercise intensity did not depend on a direct response to real-time integration of thermal afferent inputs.

We assessed the cardiorespiratory and immune response to physical exertion following secondhand smoke (SHS) exposure through a randomized crossover experiment. Data were obtained from 16 (8 women) non-smoking adults during and following a maximal oxygen uptake cycling protocol administered at baseline and at 0-, 1-, and 3- hours following 1-hour of SHS set at bar/restaurant carbon monoxide levels. We found that SHS was associated with a 12% decrease in maximum power output, an 8.2% reduction in maximal oxygen consumption, a 6% increase in perceived exertion, and a 6.7% decrease in time to exhaustion (P<0.05). Moreover, at 0-hours almost all respiratory and immune variables measured were adversely affected (P<0.05). For instance, FEV1 values at 0-hours dropped by 17.4%, while TNF-α increased by 90.1% (P<0.05). At 3-hours mean values of cotinine, perceived exertion and recovery systolic blood pressure in both sexes, IL4, TNF-α and IFN-γ in men, as well as FEV1/FVC, percent predicted FEV1, respiratory rate, and tidal volume in women remained different compared to baseline (P<0.05). It is concluded that a 1-hour of SHS at bar/restaurant levels adversely affects the cardiorespiratory and immune response to maximal physical exertion in healthy nonsmokers for at least three hours following SHS.

The World Health Organisation called for research assessing the safety of electronic cigarette (e-cigarette). We evaluated the acute effect of active and passive e-cigarette and tobacco cigarette smoking on complete blood count (CBC) markers in 15 smokers and 15 never-smokers, respectively. Smokers underwent a control session, an active tobacco cigarette smoking session, and an active e-cigarette smoking session. Never-smokers underwent a control session, a passive tobacco cigarette smoking session, and a passive e-cigarette smoking session. The results demonstrated that CBC indices remained unchanged during the control session and the active and passive e-cigarette smoking sessions (P>0.05). Active and passive tobacco cigarette smoking increased white blood cell, lymphocyte, and granulocyte counts for at least one hour in smokers and never smokers (P<0.05). It is concluded that acute active and passive smoking using the e-cigarettes tested in the current study does not influence CBC indices in smokers and never smokers, respectively. In contrast, acute active and passive tobacco cigarette smoking increase the secondary proteins of acute inflammatory load for at least one hour. More research is needed to evaluate chemical safety issues and other areas of consumer product safety of e-cigarettes, because the nicotine content in the liquids used may vary considerably.

The homeostatic mechanisms involved in the maintenance of thermal balance during exercise in the heat influence fluid balance regulation and, therefore, contribute to heat illnesses and decrements in work performance (Flouris and Cheung 2010a). In this light, the study by Wakabayashi and colleagues published recently in this journal raised considerable interest, after reporting that the heat dissipation response of Malaysian and Japanese males during exercise in humid heat stress is different (Wakabayashi et al. 2010). The experimental protocol consisted of a 60-min submaximal exercise bout in 32°C and 70% relative humidity, followed by 30 min recovery. Amongst other parameters, the authors measured rectal temperature (Tre) and hand skin temperature (Th). At baseline, these two variables were significantly different between the two groups. Specifically, Tre was higher in Malaysian individuals, while Th was higher in the Japanese. The data for these variables are presented as measured (i.e., raw) averaged every minute, despite the fact that the authors are also referring to ‘changes’ and to ‘ΔTre’ (e.g., Figure 1 in Wakabayashi et al. 2010). Interestingly, despite the baseline differences, the peak Tre and Th values measured at the end of the exercise bout were similar between the two groups. Consequently, the authors cannot convincingly argue that the heat dissipation response is different between the two groups because their data analysis does not provide statistically-derived proof for this claim.

Purpose of review: This review critically evaluates the existing biological evidence regarding the immediate and short-term respiratory consequences of secondhand smoke (SHS).

Recent findings: A 1-h exposure to SHS at bar/restaurant levels generates a marked inflammatory reaction and significant decrements on lung function. These deleterious effects of SHS are exacerbated when physical activity follows the SHS exposure, particularly in less fit individuals. The main respiratory effect mechanisms of SHS include a direct induction of growth factors resulting in airway remodelling and alterations in nitric oxide regulation. Pharmacological agents that increase either apical membrane chloride conductance or basolateral membrane potassium conductance may be of therapeutic benefit in patients with diseases related to SHS exposure. Moreover, treatment with statins has shown beneficial effects towards preventing the SHS-induced pulmonary hypertension, vascular remodelling, and endothelial dysfunction.

Summary: Based on recently discovered evidence, even brief and short-term exposures to SHS generate significant adverse effects on the human respiratory system. Future research directions in this area include the concentrations of tobacco smoke constituents in the alveolar milieu following SHS exposure, individual susceptibility to SHS, as well as pharmacological treatments for reversing the SHS-induced airway remodelling.

The human thermoregulatory system relies primarily on behavioural adaptation and secondarily on autonomic and endocrine responses for thermal homeostasis. This is because autonomic and endocrine responses have a limited capacity in preventing hyper/hypothermia in extreme environments. Until recently, the neuroanatomy of behavioural thermoregulation as well as the neuroanatomic substrate of the various thermoregulatory behaviours remained largely unknown. However, this situation has changed in recent years as behavioural thermoregulation has become a topic of considerable attention. The present review evaluates the current knowledge on behavioural thermoregulation in order to summarize the present state-of-the-art and to point towards future research directions. Findings on the fundamental distinction between thermal (dis)comfort and sensation are reviewed showing that the former drives behaviour while the latter initiates autonomic thermoregulation. Moreover, the thermosensitive neurons and thermoeffector functions of behavioural thermoregulation are presented and analysed in a detailed discussion.

Electronic nicotine delivery systems (ENDS, also called electronic cigarettes or e-cigarettes) are marketed to deliver nicotine and sometimes other substances by inhalation. Some tobacco smokers report that they used ENDS as a smoking cessation aid. Whether sold as tobacco products or drug delivery devices, these products need to be regulated, and thus far, across countries and states, there has been a wide range of regulatory responses ranging from no regulation to complete bans. The empirical basis for these regulatory decisions is uncertain, and more research on ENDS must be conducted in order to ensure that the decisions of regulators, health care providers and consumers are based on science. However, there is a dearth of scientific research on these products, including safety, abuse liability and efficacy for smoking cessation. The authors, who cover a broad range of scientific expertise, from basic science to public health, suggest research priorities for non-clinical, clinical and public health studies. They conclude that the first priority is to characterize the safety profile of these products, including in long-term users. If these products are demonstrated to be safe, their efficacy as smoking cessation aids should then be tested in appropriately designed trials. Until these studies are conducted, continued marketing constitutes an uncontrolled experiment and the primary outcome measure, poorly assessed, is user health. Potentially, this research effort, contributing to the safety and efficacy of new smoking cessation devices and to the withdrawal of dangerous products, could save many lives.

Introduction: Depression is a very prevalent mental disorder affecting 340 million people globally and is projected to become the leading cause of disability and the second leading contributor to the global burden of disease by the year 2020.

Aim: In this paper, we review the evidence published to date in order to determine whether exercise and physical activity can be used as therapeutic means for acute and chronic depression. Topics covered include the definition, classification criteria and treatment of depression, the link between β-endorphin and exercise, the efficacy of exercise and physical activity as treatments for depression, properties of exercise stimuli used in intervention programs, as well as the efficacy of exercise and physical activity for treating depression in diseased individuals.

Conclusions: The presented evidence suggests that exercise and physical activity have beneficial effects on depression symptoms that are comparable to those of antidepressant treatments.

Objective: To investigate the existing evidence about whether adherence to the Mediterranean diet may have a role as an effect modifier of active and passive smoking on human health.

Study design: Review.

Methods: An overview of emerging evidence and published studies that cover the interaction between the Mediterranean diet and smoking.

Results: Both epidemiological and laboratory studies have shown that the Mediterranean diet has a protective effect against biochemical and molecular processes that lead to cancer, cardiovascular disease and respiratory illness. Based on the high daily intake of vitamins and antioxidants, the Mediterranean diet is comprised of a number of compounds that could alter certain outcomes related to smoking. Studies have indicated that certain diseases attributable to smoking, such as lung cancer, asthma and cardiovascular disease, are inversely associated with certain antioxidants and lipids.

Conclusions: The literature indicates that the existence of a partial interaction between adherence to the Mediterranean diet and the health effects of smoking is possible. Further research is needed to lead to a conclusive statement on this hypothesis.

Caloric restriction (CR) causes a reduction in body temperature (T(b)) which is suggested to contribute to changes that increase lifespan. Moreover, low T(b) has been shown to improve health and longevity independent of CR. In this review we examine the connections between CR, T(b) and mechanisms that influence longevity and ageing. Recent findings regarding the overlapping mechanisms of CR and T(b) that benefit longevity are discussed, including changes in body composition, hormone regulation, and gene expression, as well as reductions in low-level inflammation and reactive oxygen species-induced molecular damage. This information is summarized in a model describing how CR and low T(b), both synergistically and independently, increase lifespan. Moreover, the nascent notion that the rate of ageing may be pre-programmed in response to environmental influences at critical periods of early development is also considered. Based on current evidence, it is concluded that low T(b) plays an integral role in mediating the effects of CR on health and longevity, and that low T(b) may exert independent biological changes that increase lifespan. Our understanding of the overlap between CR- and T(b)-mediated longevity remains incomplete and should be explored in future research.

We assessed autonomic nervous system modulation through changes in heart rate variability during an archery competition as well as archery performance by comparing novice and experienced adolescent archers. Seven novice (age 14.0 ± 8.5 years, body mass index 22.9 ± 4.3 kg · m−2, training experience 0.4 ± 0.3 years) and ten experienced archers (age 16.5 ± 10.3 years, body mass index 22.4 ± 3.1 kg · m−2, training experience 4.1 ± 0.9 years) volunteered. Using beat-by-beat heart rate monitoring, heart rate variability was measured for 20 s before each arrow shot during two rounds of competition. We found that, compared with novices, experienced adolescent archers: (i) take more time per shot; (ii) have a higher low frequency band, square root of the mean of squared differences between successive R-R intervals (i.e. the time elapsing between two consecutive R waves in the electrocardiogram), and percentage of successive normal-to-normal intervals greater than 50 ms; and (iii) demonstrate an increase in parasympathetic nervous system activity compared with pre-competition values. We propose that these characteristics of experienced archers are appropriate for optimal performance during competition.

The objective of this experiment was to assess whether reflex alterations in finger blood flow during repetitive hot and cold water immersion are associated with changes in rectal, tympanic, mean body temperature or heat storage. Fifteen healthy adults (eight males) volunteered. Following a 15-minute baseline period, participants were immersed in 42°C water and passively rested until their rectal temperature was raised by 0.5°C above baseline. Thereafter, they were immersed in a different water tank maintained at 12°C water temperature until their rectal temperature was decreased by 0.5°C below baseline. This procedure was conducted twice. Auto-Regressive Integrated Moving Average analysis showed that fluctuations in finger blood flow were associated with changes in mean body temperature (Ljung-Box statistic >0.05; R² = 0.67) and body heat storage (Ljung-Box statistic >0.05; R² = 0.70), but not with rectal (Ljung-Box statistic <0.05; R² = 0.54) or tympanic (Ljung-Box statistic <0.05; R² = 0.49) temperatures. It is concluded that reflex alterations in finger blood flow during repetitive hot and cold water immersions are associated with mean body temperature and the rate of body heat storage, but not with rectal and tympanic temperatures.

Middle cerebral artery blood velocity (MCAVmean) is reduced up to 30% in humans following a passive increase in internal temperature of 1–1.5°C (1). If the diameter of the MCA remains unchanged during heat stress, reductions in MCAVmean are proportional to reductions in cerebral blood flow. In support of selective brain cooling in hyperthermic humans, White et al. (7) suggest that vasodilation of the cerebral vasculature exists, which in turn increases cranial perfusion and maintains the arterial-venous temperature difference. The authors state, “it remains to be explained how MCA velocity, and presumably cranial perfusion, is reduced in hyperthermic humans if mean arterial blood pressure is maintained and MCA caliber remains constant” (4, 7). This argument ignores the potent effects of changes in carbon dioxide partial pressures on cerebral perfusion, with hypercapnia increasing and hypocapnia decreasing cerebral blood flow, respectively (6). During moderate to pronounced passive heat stress, arterial and end-tidal carbon dioxide partial pressures decrease upward to 8 Torr (1, 2). Importantly, an 8-Torr reduction in arterial carbon dioxide partial pressure is estimated to reduce cerebral blood flow by ∼24% (5) through increases in resistance of the cerebral arterioles “downstream” from the MCA (3). Thus the clear and robust reduction in MCAVmean during passive heat stress is likely due primarily to decreases in carbon dioxide partial pressures causing increases in vascular resistance of cerebral arterioles distal to the MCA.

Objectives: To generate a model that predicts fingertip blood flow (BFf) and to cross-validate it in another group of subjects.

Methods: We used fingertip temperature (Tf), forearm temperature minus Tf (TFor-f), rectal temperature (Tre), and their changes across time (lagT) to estimate BFf. Ten participants (six male, four female) were randomly divided into “model” and “validation” groups. We employed a passive hot–cold water immersion protocol during which each participant’s core temperature increased and decreased by 0.5°C above/below baseline during hot/cold conditions, respectively. A hierarchical multiple linear regression analysis was introduced to generate models using temperature indicators and lagT (independent variables) obtained from the model group to predict BFf (dependent variable).

Results: Mean BFf (109.5 ± 158.2 PU) and predicted BFf (P-BFf) (111.4 ± 136.7 PU) in the model group calculated using the strongest (R2 = 0.766, p < 0.001) prediction model [P-BFf =Tf× 19.930 + lag4Tf × 74.766 + lag4Tre × 124.255 – 447.474] were similar (p = 0.6) and correlated (r = 0.880, p < 0.001). Autoregressive integrated moving average time-series analyses demonstrated a significant association between P-BFf and BFf (R2 = 0.381; Ljung–Box statistic = 8.097; p < 0.001) in the validation group.

Conclusions: We provide a model that predicts BFf via two practical temperature indicators that can be implemented in both clinical and field settings.

It was with great interest that we read the Journal of Applied Physiology Viewpoint on the 2-h marathon barrier (3). We would argue that, alongside having a superlative V̇o2max, lactate threshold, and running economy, it will be required for this athlete to have an individualized and aggressive fueling strategy coupled with a predisposition for high exogenous CHO oxidation (CHOexog), without a history of GI distress. It is clear that supplemented carbohydrate (CHO) improves prolonged endurance performance (>90 min) compared with water (2). Furthermore, recent evidence has demonstrated a positive dose-response relationship between supplemented CHO, CHOexog, and endurance performance; where 60 g CHO/h outperformed either 15 or 30 g CHO/h (5). The maximal CHOexog with single CHO sources appears to be ∼1 g/min due to limitations of the intestinal transporters (1). However, despite any individual differences in CHOexog or history of GI distress (4), CHOexog is not dependent on body weight (BW), as a recent analysis has shown no relationship between BW and CHOexog (1). Accordingly, a 56-kg runner is able to oxidize ∼20% more per kg BW compared with a 70-kg runner with a given CHOexog rate of ∼1 g/min (1.07 vs.0.86 g CHO·h−1·kg BW−1). Therefore, there appears to be a distinct CHOexog advantage for lighter marathon runners compared with heavier. Thus the future 2-h marathon runner will feature a low BW, both for improved thermoregulation, but also optimal CHOexog per kg BW. All of these elements will need to be possessed by the first athlete to break the 2-h marathon barrier.

The authors of “Expending our physical activity (measurement) budget wisely” (2) discussed and provided data on potential pitfalls with using self-reported physical activity (PA) to understand interactions with health. The authors rightfully suggest that despite the major efforts placed into developing reliable and valid questionnaires, they remain largely inaccurate for the majority of adults (1). The error is thought to originate from a disproportionate focus on volitional type exercise (biking, jogging, and walking), while not capturing low to moderate intensity movements that accumulate a significant proportion to total activity energy expenditure (6). However, while I agree with the author’s conclusions, the use of self-reported behaviors will remain a staple in telephone-based and large epidemiological studies. We simply can’t ask for objectively measured PA in such designs and we can’t afford to lose this vital information for understanding demographics of PA at a global level. As an example, there are several national and international studies that will continue to use such methodology for understanding PA and health (3, 5). Therefore, improved questionnaires should be created to enhance capturing nonexercise (household chores, standing, walking for purpose) and sedentary behaviors (sitting or lying) that are uniquely associated with public health. The inclusion of such behaviors in these questionnaires will help distinguish types of activities that might have a critical role in health and potentially distinct interactions with volitional exercise. The development of such questionnaires is ongoing for these purposes (4).

The malleability of mammalian biology during early life, which carries considerable weight throughout the course of the lifespan, may contribute to the creation of a human phenotype ideal for prime physical performance. In this article, the authors consider the East African cohort of exceptional athletes that dominate marathon performance. Since entering international marathon competition in 1960, East Africans have competed at the front of the pack and now hold the top 10 men’s marathon times. The authors present lines of evidence supporting that exposure to factors such as altitude and early metabolic adjustments that are inherent in East African early life exert a strong influence in later life physical performance and may collide with a genetic advantage to induce biological changes that allow for a more robust biological response to training in later life.

A vast number of studies on the unfavorable effects of secondhand smoke (SHS) exist within the international literature, the majority of which evaluate longitudinal epidemiological data. Although limited, the experimental studies that assess the acute and short-term effects of exposure to SHS are also increasing in number. They include cellular, animal, and human studies that indicate a number of pathophysiological mechanisms through which the deleterious effects of SHS may arise. This current review evaluates the existing biological evidence regarding the acute health effects of SHS exposure. Analyses on the inhaled toxicants and the carcinogenicity of SHS are included as well as in-depth discussions on the evidence for acute SHS-induced respiratory, cardiovascular, metabolic, endocrine and immune effects, and SHS-induced influences on oxygen delivery and exercise. The influence of the length of exposure and the duration of the observed effects is also described. Moreover, recent findings regarding the underlying pathophysiological mechanisms related to SHS are depicted so as to generate models that describe the SHS-induced effects on different systems within the human body. Based on the presented biological evidence, it is concluded that brief, acute, transient exposures to SHS may cause significant adverse effects on several systems of the human body and represent a significant and acute health hazard. Future research directions in this area include research on the concentrations of tobacco smoke constituents in the alveolar milieu following SHS exposure, individual susceptibility to SHS, as well as the effects of SHS on neurobehavioral activity, brain cell development, synaptic development, and function.

We examined the efficacy of tympanic (T(ty)) and exhaled breath (T(X)) temperatures as indices of rectal temperature (T(re)) by applying heat (condition A) and cold (condition B) in a dynamic A-B-A-B sequence. Fifteen healthy adults (8 men; 7 women; 24.9 +/- 4.6 years) volunteered. Following a 15 min baseline period, participants entered a water tank maintained at 42 degrees C water temperature and passively rested until their T(re) increased by 0.5 degrees C above baseline. Thereafter, they entered a different water tank maintained at 12 degrees C water temperature until their T(re) decreased by 0.5 degrees C below baseline. This procedure was repeated twice (i.e. A-B-A-B). T(ty) demonstrated moderate response delays to the repetitive changes in thermal balance, whereas T(X) and T(re) responded relatively fast. Both T(ty) and T(X) correlated significantly with T(re) (P < 0.05). Linear regression models were used to predict T(re) based on T(ty) and T(X). The predicted values from both models correlated significantly with T(re) (P < 0.05) and followed the changes in T(re) during the A-B-A-B thermal protocol. While some mean differences with T(re) were observed (P < 0.05), the 95% limits of agreement were acceptable for both models. It is concluded that the calculated models based on tympanic and exhaled breath temperature are valid indicators of core temperature.

Our objective was to characterise sweat rate responses in a hot environment during rest and subsequent increasing levels of exercise in relation to thermometrically (i.e., rectal, tympanic, mean skin and mean body temperatures) and calorimetrically derived (i.e., change in body heat storage) thermal parameters. Ten healthy males volunteered and entered an environmental chamber set at 42 degrees C. Participants rested seated during their first hour inside the chamber. Thereafter, they exercised to volitional exhaustion on a cycle ergometer at 20 W with step increments of 20 W h(-1). Across time, fluctuations in sweat rate were systematically associated with similar fluctuations in the integral of body heat storage (t = 13.16, P < 0.001), but not rectal (t = 0.98, P > 0.05), tympanic (t = 0.81, P > 0.05), mean skin (t = 0.12, P > 0.05), or mean body (t = 0.93, P > 0.05) temperatures. In addition, 95% limits of agreement and regression analyses showed that the changes in sweat rate demonstrated the highest agreement and strongest associations with changes in the integral of body heat storage. It is concluded that in a hot environment during rest and subsequent increasing levels of exercise sweat rate is associated with the cumulative changes in the rate of body heat storage.

We assessed the validity and reliability of the new 15m square shuttle run test (SST) for predicting laboratory treadmill test (TT) maximal oxygen uptake (VO(2 max)) compared to the 20 m multistage shuttle run test (MST) in 45 adult males. Thirty participants performed a TT and a SST once to develop a VO( 2max) prediction model. The remaining 15 participants performed the TT and MST once and the SST twice for cross-validation purposes. Throughout testing V O(2max) was determined via portable indirect calorimetry while blood lactate concentration was assessed at the fifth recovery minute. Comparisons of TT V O(2 max) (51.3+/-3.1 ml kg(-1)min(-1)) with SST measured (51.2+/-3.2 ml kg(-1)min(-1)) and predicted (50.9+/-3.3 ml kg(-1)min(-1)) V O(2 max) showed no differences while TT blood lactate was higher compared to SST (10.3+/-1.7 mmol vs. 9.7+/-1.7 mmol, respectively). In contrast, MST measured (53.4+/-3.5 ml kg(-1)min(-1)) and predicted (57.0+/-4.5 ml kg(-1)min(-1)) V O(2 max) and blood lactate (11.2+/-2.0 mmol) were significantly higher compared to TT. No test-retest differences were detected for SST measured and predicted V O(2 max) and blood lactate. It is concluded that the SST is a highly valid and reliable predictive test for V O(2 max).

Recent work by our group showed that cold-induced vasodilation (CIVD) is a centrally originating phenomenon caused by sympathetic vasoconstrictor withdrawal; it is dependent on excess heat, and it may be triggered by excess heat with the purpose of preserving thermal balance (Flouris et al. 2008; Flouris and Cheung 2009a, b). To this effect, Daanen and Layden (2009) recently argued that, instead, our data show that CIVD is of peripheral origin. Thus, our aim in this letter is to briefly clarify misconceptions that may have led Daanen and Layden to questionable inferences.

At a time when the number of smokers worldwide is at its highest, and antismoking policies are proliferating, the sector for alternative smoking products is in a froth of excitement about the potential to increase its market share and revenues. One of the most recent products in the market is the electronic cigarette (e-cigarette), which is intended, whether overtly stated or implied, to reduce concentrations of toxic compounds in mainstream and sidestream smoke and to help smokers give up. They are battery powered devices that simulate tobacco cigarettes by vaporising nicotine and other chemicals into an inhalable vapour. The scarce data available so far indicate that sales of e-cigarettes are rising, yet recently the US Food and Drug Administration (FDA) expressed serious concerns about their safety.

Objective Millions of non-smokers suffer daily passive smoking (PS) at home or at work, many of whom then have to walk fast for several minutes or climb a few sets of stairs. We conducted a randomised single-blind crossover experiment to assess the cardiorespiratory and immune response to physical activity following PS.

Design Data were obtained from 17 (eight women) non-smoking adults during and following 30 minutes of moderate cycling administered at baseline and at 0 hour, 1 hour and 3 hours following a 1-hour PS exposure set at bar/restaurant PS levels.

Results We found that PS was associated with a 36% and 38.7% decrease in mean power output in men and women, respectively, and that this effect persisted up to 3 hours (p<0.05). Moreover, at 0 hour almost all cardiorespiratory and immune variables measured were markedly reduced (p<0.05). For instance, FEV1 values at 0 hour dropped by 10.2% in men and 10.8% in women, while IL-5 increased by 59.2% in men and 44% in women, respectively (p<0.05). At 3-hour mean values of respiratory quotient, mean power, perceived exertion, cotinine, FEV1, IL-5, IL-6 and INFγ in both sexes, recovery diastolic and mean arterial pressure, IL-4 and TNFα in men, as well as percentage predicted FEV1 in women remained different compared to baseline (p<0.05). Also, some of the PS effects were exacerbated in less fit individuals.

Conclusion It is concluded that 1 hour of PS at bar/restaurant levels adversely affects the response to moderate physical activity in healthy non-smokers for at least 3 hours following PS.

Despite the recent campaigns to eliminate smoking and hinder the detrimental effects of passive smoking (PS), actual smoking rates still increase worldwide. Several physiological systems, with the respiratory being the primary, are disrupted by PS and progressively deteriorate through chronic exposures. This is of particular importance in children, given that respiratory complications during childhood can be transferred to adulthood, lead to significantly inferior health profiles. Hence, it is no surprise that children that are exposed to PS either in utero or during their adulthood may have an increased prevalence of allergies and asthma. However, investigating the acute effects of PS in children is inherently limited by complexities pertaining mainly to ethical constrains. Knowledge of the acute effects could be very important as it is the dose-dependant acute effects of passive smoking that lead to the long-term adaptations linked with the development of allergy and asthma. Current available data show that the chemical and carcinogenic constituents of tobacco have profound effects on children’s health as they may disrupt normal biological development. PS appears to have pronounced effects on respiratory parameters that promote asthma development and persistent wheezing rather than other allergies. As such, PS exposure has to be eliminated and researchers have to develop interventions for supporting smoking cessation as well as minimised PS exposure either this is in utero or during childhood.

Growing evidence suggests that the effects of second hand smoke (SHS) exposure contribute to disruptions in thyroid function. Toxic elements contained in cigarette smoke, such as thiocyanate, may be partially responsible for impaired thyroid hormonogenesis. SHS-induced inflammatory stress, namely interleukin 1beta (IL-1beta), impairs thyroid hormonogenesis and iodine uptake; initiates interleukin 6 (IL-6) production from thyroid epithelial cells and stimulates the expression of molecules that exacerbate thyroid autoimmunity. The link between SHS exposure and thyroid autoimmune disease is not well documented and thus, remains to be fully understood. Elevated inflammatory stress and thyroid hormone secretion in response to SHS exposure initiates catabolic processes that alter body composition via lean body mass breakdown; translating to an elevation in resting energy expenditure of approximately 10%. The combination of certain biological factors, such as sex and/or existing thyroid disease may stimulate differential SHS-induced effects on thyroid function. Nevertheless, exposure to SHS disturbs vital human processes via thyroid disruption.

The objective of this paper was to review the epidemiological literature examining the association between secondhand smoke (SHS) and cardiovascular disease (CVD). Specifically, we examined the various screening methods available in assessing smoking behaviour and quantifying nicotine absorption. Further, we considered the natural history of those exposed to SHS and the associated risk of CVD. We reviewed routine methods used to assess exposure to SHS; evaluated the utility of subjective screening questions regarding smoking behaviour and examined the efficacy of nicotine and cotinine biomarkers used to quantify SHS exposure in epidemiological and clinical-based research. Self-reporting is practical and cost-effective in identifying smoking behaviour patterns, but is subject to recall bias and underestimation of exposure, especially in the presence of children. Nicotine and cotinine biomarkers have proven valuable in quantifying tobacco smoke absorption and establishing biological plausibility. A combination of SHS self-reported and biomarker evaluation provide the most stringent method of establishing exposure. Sufficient evidence is reported in epidemiological research to support a causal association between SHS exposure and increased risks of CVD morbidity and mortality among both men and women. The risk of developing an acute cardiac syndrome or chronic lifetime coronary events is at least 30%. Similarly, reduction in the incidence of a myocardial infarction decreases by nearly 50% in the absence of SHS. Considering the biological plausibility and dose-response relationship between SHS and CVD, effective interventions that incorporate a comprehensive screening method of behavioral and biological measures of exposure coupled with efficacious treatment should elicit favorable change for at-risk populations.

This study examined the effect of birth season on fetal development and longevity using two independent databases of all Greek citizens that were born (total: 516,874) or died (total: 554,101) between 1999 and 2003. We found significantly increased birth weight, gestational age, and longevity in individuals born during the autumn and winter seasons of the year. These individuals also demonstrated statistically significantly lower prevalence rates for fetal growth restriction and premature birth. Furthermore, we found that increased temperature at birth was associated with adverse effects on fetal development and longevity. In conclusion, our results show strong effects of season of birth on fetal development and longevity mediated, at least in part, by environmental temperature at time of birth.

We examined the effect of thermal balance perturbation on cold-induced vasodilation through a dynamic A-B-A-B design applying heat (condition A) and cold (condition B) to the body’s core, while the hand is exposed to a stable cold stimulus. Fifteen healthy adults (8 men, 7 women) volunteered. Applications of heat and cold were achieved through water immersions in two tanks maintained at 42 and 12°C water temperature, respectively, in an A-B-A-B fashion. Throughout the experiment, the participants’ right hand up to the ulnar styloid process was placed inside a temperature-controlled box set at 0°C air temperature. Results demonstrated that cold-induced vasodilation occurred only during condition B and at times when body heat content was decreasing but rectal temperature had not yet dropped to baseline levels. Following the occurrence of all cold-induced vasodilation events, rectal temperature was reduced, and the phenomenon ceased when rectal temperature fell below baseline. Heart rate variability data obtained before and during cold-induced vasodilation demonstrated a shift of autonomic interaction toward parasympathetic dominance, which, however, was attributed to a sympathetic withdrawal. Receiver operating characteristics curve analyses demonstrated that the cold-induced vasodilation onset cutoff points for rectal temperature change and finger temperature were 0.62 and 16.76°C, respectively. It is concluded that cold-induced vasodilation is a centrally originating phenomenon caused by sympathetic vasoconstrictor withdrawal. It is dependent on excess heat, and it may be triggered by excess heat with the purpose of preserving thermal balance.

Aim: Given the controversy regarding cardiovascular responses and heart rate variability (HRV) in underwater conditions, the authors assessed the combined effect of psychological stress and scuba diving on cardiac autonomic modulation measured through HRV during and following a diving mission.

Methods: Ten healthy adults (three females; seven males; Body Mass Index [BMI] 23.7 + or – 2.1; age 26.4 + or – 2.9) performed a 20-minute dive in a neutral buoyancy water tank (27 degrees C) at a depth of five meters. The dive scenario involved repairing components of a scientific instrument using a high fidelity task mock-up. Data for HRV (three from the time domain and three from the frequency domain) were obtained for 20 minutes prior to (PRE), during (DIVE), and for 20 minutes following (POST) the dive sortie.

Results: Heart rate in DIVE was increased when compared to PRE and POST (74 + or – 10 vs. 108 + or – 16 vs. 72 + or – 8 beats x min(-1), respectively). The time domain measure pNN50 (37.3 + or – 16.9 vs. 14.1 + or – 10.1 vs. 22.0 + or – 12.2%, respectively), and the R-R interval (0.72 + or – 0.26 vs. 0.59 + or – 0.11, vs. 0.86 + or – 0.24, respectively) showed a significant decrease in DIVE compared to PRE and POST, while no changes were detected in the frequency domain indices between measurements. During POST, the square root of the mean of squared differences between successive intervals returned to PRE levels, but pNN50 values remained decreased at DIVE levels.

Conclusions: These findings suggest a decrease in parasympathetic indices during a psychologically challenging scuba dive and a delay in vagal reactivation during the 20-minute period following the dive.

Objective and Design: To detect the dependable criteria of behavioural thermoregulation through modelling temperature fluctuations of individuals allowed to freely manipulate inlet water temperature of a liquid conditioning garment (LCG) during 130 min of passive exposure to −20°C interspersed with a 10 min period of moderate exercise at the 65th minute using a double-blind experiment.

Participants: Eleven volunteers (5 women; 23.40 (SD 2.09) years; BMI: 23.24 (SD 2.19)) who lacked previous experience with LCG and cold exposure experiments.

Results: Despite variations in core and skin temperatures, thermal comfort, thermal sensation, and mean body temperature did not fluctuate significantly over time. Participants were able to find a desired level of LCG inlet temperature within 25 minutes which was maintained at similar levels until the 65th minute of the cold exposure. During exercise, LCG inlet water temperature decreased significantly. Regression models demonstrated that mean skin temperature and change in mean body temperature were significantly associated with thermal comfort and thermal sensation. Subsequent models revealed that, although all temperature variables were associated with LCG inlet water temperature, the coefficient of determination mainly depended on mean skin temperature and change in mean body temperature. The involvement of skin temperature was anticipated as the liquid conditioning garment was in contact with the skin.

Conclusions: Humans generate conscious thermoregulatory responses in resting and exercise conditions during exposures to cold environments that are aimed towards maintaining a threshold mean body temperature, rather than temperature changes in individual body regions.

We appreciate the letter of Dr. Daanen (Daanen 2009) with regards to our methodology for inducing cold-induced vasodilation (CIVD) in our experiment (Flouris et al. 2008) as it creates a much-needed opportunity to discuss this vital aspect of CIVD that has not received much attention. It has been observed for some time now that a wide variety of CIVD-inducing techniques have been adopted (Sendowski et al. 1997). Water immersion has been used in many experiments, yet the water temperature varies between 0°C (Adams and Smith 1962; Daanen and van der Struijs 2005) and 8°C (Daanen et al. 1997; Reynolds et al. 2007) while the immersion time varies between 1 and 40 min (Sendowski et al. 1997; Daanen and Ducharme 1999). CIVDs have been also recorded during conductive cooling from touching cold materials (Havenith et al. 1992; Chen et al. 1994), while many experiments have adopted local or whole body exposures to cold air. With regards to local air exposure, air temperatures ranging from 10 to −18°C have been used to cool the fingers for 2 h in order to induce CIVD (Kramer and Schulze 1948). On the other hand, whole body exposures of 10°C (Montgomery and Williams 1977; Brajkovic and Ducharme 2006), 1°C (Steegmann Jr 1979), 0°C (Shitzer et al. 1998a; Brajkovic and Ducharme 2006), −7°C (Santee et al. 1990), −10°C (Brajkovic and Ducharme 2006), and −17°C (Shitzer et al. 1991, 1998b; Shitzer 1998) lasting up to 2 h have been adopted as CIVD-inducing techniques in humans. Experiments in rats have identified CIVDs in whole body exposures at ambient temperatures of 5 and 10°C (Berry et al. 1984). Our experiment (Flouris et al. 2008) incorporated a 130-min exposure to −20°C, a protocol that creates the most severe cold stress of all whole body air exposure experiments in the CIVD literature to date.

Rationale: The acute effect of secondhand smoke (SHS) on lung function and the duration of system disruption remain unknown.

Objectives: To assess the SHS effects and their duration on lung function and inflammatory markers.

Methods: In a randomized single-blind crossover experiment data were obtained from 16 (8 women) nonsmoking adults at baseline and at 0, 1, and 3 hours after a 1-hour SHS exposure set at bar/restaurant SHS levels.

Measurements and Main Results: Serum and urine cotinine, lung function, and cytokines IL-4, IL-5, IL-6, tumor necrosis factor (TNF)-α, and IFN-γ. At 0 hours most lung function parameters were significantly reduced (indicative: FEV1, 4.3 ± 0.4 vs. 3.8 ± 0.3 L; FEV1/FVC, 0.9 ± 0.1 vs. 0.8 ± 0.1; P < 0.05) but at 3 hours they were at baseline levels. In contrast, cotinine (serum, 8.9 ± 3.2 vs. 35.5 ± 10.2 ng·ml−1), IL-4 (41.3 ± 5.8 vs. 44.2 ± 4.5 pg·ml−1), IL-5 (36.1 ± 3.2 vs. 60.1 ± 7.0 pg·ml−1), IL-6 (2.5 ± 0.3 vs. 7.6 ± 1.4 pg·ml−1) and IFN-γ (0.3 ± 0.2 vs. 0.6 ± 0.2 IU·ml−1) at 3 hours were higher than at baseline (P < 0.05). IL-4 and TNF-α increased only in men, whereas IL-5, IL-6, and IFN-γ were different between sexes after exposure (P < 0.05). Regression analyses revealed inverse associations of FEV1 and FEV1/FVC ratio with IL-5 (P < 0.05) in men and with IL-5 (P = 0.01), IL-6 (P < 0.001), IFN-γ (P = 0.034) and serum cotinine (P < 0.001) in women.

Conclusions: We conclude that 1 hour of SHS exposure at bar/restaurant levels is accompanied by significant decrements on lung function and marked increases in inflammatory cytokines, particularly in men. More importantly, whereas most smoke-induced effects on lung function appear to recede within 60 minutes, inflammatory cytokines remain elevated for at least 3 hours after exposure to SHS.