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It has been observed that high temperature exposure is associated with a reduction in lung function and some possible biological mechanisms have been suggested. However, it is unclear if thermal perception plays a role in the association. From September 3rd to 15th, 2018, in Guangzhou, China, we repeatedly measured daily thermal perception and lung function among 126 participants with outdoor military training. We performed a linear mixed model and stratified analyses by the origin of students, gender, and the training period to evaluate the effects of thermal perception on lung function. A total of 399 measurements were collected. Per vote increase in thermal sensation vote towards the "hot" direction was associated with a - 0.04 L (95% CI: - 0.08 to - 0.01) decrease in forced vital capacity (FVC), and - 0.04 L (95% CI: - 0.08 to - 0.01) decrease in forced expiratory volume in 1 s (FEV

PURPOSE: We compared the effectiveness of three field-based training programs, namely military-based heat acclimatization (MHA), isothermic conditioning (IC) and interval training (IT), in inducing physiological adaptations in tropical natives. METHODS: Fifty-one untrained tropical native males (mean ± standard deviation: age, 25 ± 2 yr; body mass index, 23.6 ± 3.2 kg·m(−2); body fat, 19% ± 5%; 2.4-km run time, 13.2 ± 0.9 min) donned the Full Battle Order attire (22 kg) and performed a treadmill route march heat stress test in an environmental chamber (dry bulb temperature, 29.9°C ± 0.5°C; relative humidity, 70% ± 3%). Heat stress tests were conducted before (PRE) and after (POST) a 2-wk training intervention consisting of either a MHA (n = 17, 10 sessions of military-based heat acclimatization), IC (n = 17, 10 sessions with target gastrointestinal temperature (T(gi)) ≥ 38.5°C) or IT (n = 17, six sessions of high-intensity interval training) program. T(gi), HR, mean weighted skin temperature (T(sk)), physiological strain index (PSI) and thigh-predicted sweat sodium concentration ([Na(+)]) were measured and analyzed by one-factor and two-factor mixed design ANOVA with a 0.05 level of significance. RESULTS: Field-based IC induced a greater thermal stimulus than MHA (P = 0.029) and IT (P < 0.001) during training. Reductions in mean exercise T(gi) (−0.2°C [−0.3°C, 0.0°C]; P = 0.009)(,) PSI (−0.4 [−0.7, −0.1]; P = 0.015) and thigh-predicted sweat [Na(+)] (−9 [−13, −5 mmol·L(−1)]; P < 0.001) were observed in IC but not MHA and IT (all P > 0.05). Resting HR (MHA, −4 bpm [−7, 0 bpm]; P = 0.025; IC, −7 bpm [−10, −4 bpm]; P < 0.001; IT, −4 bpm [−8, −1 bpm]; P = 0.008) and mean exercise HR (MHA, −4 [−8, 0 bpm]; P = 0.034; IC, −11 bpm [−15, −8 bpm]; P < 0.001, IT = −5 bpm [−9, −1 bpm]; P = 0.012) were lowered in all groups after training. Isothermic conditioning elicited a greater attenuation in mean exercise HR and thigh-predicted sweat [Na(+)] relative to MHA (both P < 0.05). No between-group differences were observed when comparing MHA and IT (all P > 0.05). CONCLUSIONS: Isothermic conditioning induced a more complete heat-adapted phenotype relative to MHA and IT. Interval training may serve as a time efficient alternative to MHA.

The main aim of this study was to examine the influence of ischemic preconditioning (IPC) on maximal accumulated oxygen deficit (MAOD). We conducted a three-arm and assessor-blinded randomized, controlled crossover study

Objectives To determine the physiological effects of multiple stressors including energy deficit during a 62-day Ranger course in a hot-humid environment. Design Prospective cohort design. Methods Food intake data were collected daily and energy expenditure at each of the three phases of the course was estimated by the doubly-labeled water method. Anthropometry, hydration status, stress and metabolic hormones, handgrip strength and lower explosive power were measured at the start and at the end of each phase. Results Seventeen male participants (age: 24.5 ± 3.2 years, height: 173.9 ± 5.1 cm, body mass: 69.3 ± 3.2 kg, BMI: 22.9 ± 0.9 kg/m2, percent body fat: 14 ± 5%) completed the study. Mean total daily energy expenditure was 4756 kcal/day and mean daily energy intake was 3882 kcal/day. An 18% energy deficit resulted in an average body mass loss of 4.6 kg, comprising mostly fat mass. Participants with higher baseline adiposity (>15% body fat) lost more fat mass and gained (rather than lost) muscle mass compared to those with lower baseline adiposity. Handgrip strength declined only at the end of Phase I, while lower body explosive power declined progressively throughout the course. Lean mass in arms and legs was correlated with initial grip strength and lower body explosive power, but only at the start of the course. Conclusions Physiologically demanding Ranger training in an equatorial environment is at least as metabolically demanding and stressful as other similar high-risk training courses, as demonstrated by the stress and metabolic endocrine responses, changes in body composition, and reduction in explosive power. Moreover, the smaller body size of Asian soldiers may confer an energetic advantage over larger sized Western counterparts.

Semi-outdoor space can be used as an alternative to short-term office activities to save office energy consumption and promote a healthy and nature-based working environment. This study evaluated the suitability of semi-outdoor space in four aspects including environmental measurements, physiological measurements, subjective measurements and cognitive performance tests. However, the manual processing and analysis of such multidimensional data can be time-consuming and error-prone. Hence, the objective of this study was to develop a semi-automatic method to manage and analyze the data from different instruments and platforms and two open-source applications (a stroop color and word test and a digit span test) for cognitive performance tests. These codes were critical to the success of the project, providing an effective framework for data extraction, data pre-processing, data analysis and performance tests. Eighty-nine people participated in the experiment of evaluation of thermal comfort, cognitive performance, physiological performance and environmental parameters in semi-outdoor spaces in a tropical setting. Each participant received cognitive tests to assess their selective attention, short-term memory, concentration and creativity quotient. Concurrently, qualitative measurements were conducted to assess thermal sensation, thermal comfort and thermal acceptability. The heart rate, skin temperature, and skin conductance of participants were measured throughout the experiments. Microclimatic variables such as illuminance, noise levels, dry-bulb air temperature, global temperature, relative humidity, air speed, and air direction were monitored simultaneously. To understand the effects of semi-outdoor spaces on participant performance, this study recorded participant performance in different environments through controlled experiments. Data related to participants in different settings include those shared (e.g., environmental measurement), and data unique to each participant (e.g., physiological performance). The results revealed that the subjects’ cognitive and physiological performance did not change significantly after switching to the semi-outdoor space due to the availability of natural and mechanical ventilation, suggesting that short-term office activities in the semi-outdoor space are feasible in the tropics.

Objectives The ACSM recommends drinking to avoid loss of body mass >2% during exercise to avert compromised performance. Our study aimed to assess the level of dehydration in elite runners following a city marathon in a tropical environment. Design Prospective cohort design. Methods Twelve elite runners (6 males, 6 females; age 24–41 y) had body mass measured to the nearest 0.01 kg in their race attire immediately before and after the 2017 Standard Chartered Singapore Marathon 2017. Body mass change was corrected for respiratory water loss, gas exchange, and sweat retained in clothing, and expressed as % of pre-race mass (i.e. % dehydration). Results Data are expressed as means ± SD (range). Dry bulb temperature and humidity were 27.9 ± 0.1 °C (27.4–28.3 °C) and 79 ± 2% (73–82%). Finish time was 155 ± 10 min (143−172 min). Male runners finishing positions ranged from 2–12 out of 7627 finishers, whilst female runners placed 1–8 out of 1754 finishers. Body mass change (loss) and % dehydration for all runners were 2.5 ± 0.5 kg (1.8–3.5 kg) and 4.6 ± 0.9% (3.6–6.8%). Male runners experienced body mass loss of 2.8 ± 0.5 kg and 4.9 ± 1.2% while females experienced body mass loss of 2.1 ± 0.2 kg and 4.3 ± 0.6%. Conclusions Despite experiencing dehydration (4.6% body mass loss) two-fold higher than current fluid replacement guidelines recommend (≤2%), elite male and female runners performed successfully and without medical complication in a hot weather marathon.

The Warsaw International Mechanism for Loss and Damage has identified increasing temperatures as a key slow onset event. However, it is the resulting increases in short-term heat events — heatwaves — that have so far been the primary focus of risk assessment and policy, while gradual and sustained increases in temperature have received less attention. This is a global issue but particularly important in tropical and subtropical regions already chronically exposed to extreme heat. This paper reviews recent analyses of intensifying seasonal and year-round extreme heat exposures and how this affects daily life, including worker productivity, health and wellbeing, reduced GDP and economic viability. It frames this as a slow onset event and closes with a brief indication of tools available to assess and address these risks.

Objectives We investigated the thermoregulatory responses to ice slurry ingestion during low- and moderate-intensity exercises with restrictive heat loss. Design Randomised, counterbalanced, cross-over design. Methods Following a familiarisation trial, ten physically active males exercised on a motorised treadmill at low-intensity (L; 40% VO2max) or moderate-intensity (M; 70% VO2max) for 75-min, in four randomised, counterbalanced trials. Throughout the exercise bout, participants donned a raincoat to restrict heat loss. Participants ingested 2 g kg−1 body mass of ambient water (L + AMB and M + AMB trials) or ice slurry (L + ICE and M + ICE trials) at 15-min intervals during exercise in environmental conditions of Tdb, 25.1 ± 0.6 °C and RH, 63 ± 5%. Heart rate (HR), gastrointestinal temperature (Tgi), mean weighted skin temperature (Tsk), estimated sweat loss, ratings of perceived exertion (RPE) and thermal sensation (RTS) were recorded. Results Compared to L + AMB, participants completed L + ICE trials with lower ΔTgi (0.8 ± 0.3°C vs 0.6 ± 0.2 °C; p = 0.03), mean RPE (10 ± 1 vs 9 ± 1; p = 0.03) and estimated sweat loss (0.91 ± 0.2 L vs 0.78 ± 0.27 L; p = 0.04). Contrastingly, Tgi (p = 0.22), Tsk (p = 0.37), HR (p = 0.31), RPE (p = 0.38) and sweat loss (p = 0.17) were similar between M + AMB and M + ICE trials. RTS was similar during both low-intensity (4.9 ± 0.5 vs 4.7 ± 0.3; p = 0.10) and moderate-intensity exercise (5.3 ± 0.47 vs 5.0 ± 0.4; p = 0.09). Conclusions Per-cooling using ice slurry ingestion marginally reduced thermal strain during low-intensity but not during moderate-intensity exercise. Ice slurry may be an effective and practical heat mitigation strategy during low-intensity exercise such as in occupational and military settings, but a greater volume should be considered to ensure its efficacy.

Purpose To (i) describe the characteristics of physical fitness and cardiometabolic risk in Chinese university students with normal-weight obesity (NWO); (ii) assess the association between NWO with physical fitness and cardiometabolic risk. Methods A total of 249 participants from the 2018 Shanghai University of Sport Alumni Health Cohort Study in China formed the study cohort. NWO was defined as normal body mass index (17.9-23.9 kg/m2 for males; 17.2-23.9 kg/m2 for females) but with excess body-fat percentage (≥20% for males; ≥30% for females). Body composition was assessed by dual-energy X-ray absorptiometry. Physical-fitness scores were calculated from a battery of sex-specific tests. Cardiometabolic risk was calculated using a continuous clustered risk (MetS) score. Results We found that 16.7% of male and 45.3% of female university students were classified as having NWO. Participants with NWO showed worse cardiorespiratory fitness than those with normal weight (NW) (male NWO (37±8) vs male NW (41±6) mL/kg/min, p

It is well-established that appropriate hydration practices are essential in promoting health and optimizing performance and recovery. However, evidence-based hydration guidelines may not be adopted due to cultural differences across countries, such as religious beliefs, traditions, preferences, and beverage availability. Examples of hydration practices influenced by culture include beer consumption after sports in Western countries, consumption of sugarcane juice in India and Ramadan fasting among Muslims. For most cultural hydration practices, there is limited scientific evidence on their effects on rehydration, exercise performance, and recovery. Despite possible benefits of various hydration practices on exercise performance and recovery, they are inconsistent with current evidence-based hydration recommendations. More research on the impacts of cultural hydration differences on physiology, performance, and recovery is warranted to allow evidence-based guidelines and advisories.

Despite the emerging carbon neutrality pledges from different countries, it is still unclear how much these pledges would cost and how the costs would compare with the economic benefits. Comparisons at the country level are important for tightening country-specific emissions trajectories to keep the temperature limit targets outlined in the Paris Agreement within reach. We aimed to systematically estimate avoided heat-related labour productivity losses against the costs of climate change mitigation at country and regional levels.In this modelling study, to address the above-mentioned research gaps, we first selected two representative climate change scenarios (Representative Concentration Pathway 6.0 [RCP6.0] scenario, a higher warming scenario representing limited mitigation pledges before the Paris Agreement with around 3°C warming by the end of this century; and RCP2.6 scenario, a lower warming scenario assuming global temperature rise is limited to 2°C) and estimated heat-related labour productivity loss using the exposure-response function at country and regional levels. By representing the direct heat-related labour productivity losses in a multiregional global computable general equilibrium model, we then did a benefit-cost analysis to quantify the economic benefits of avoided heat-related labour productivity losses as well as the estimated reduction in gross domestic product (GDP) related to carbon reduction.By 2100, the overall economic losses due to heat-related labour productivity loss could range from about 1·5% of global GDP under the RCP6.0 scenario to about 0·1% of global GDP under the RCP2.6 scenario. The productivity losses will be highly concentrated in low-latitude regions, especially in southeast Asia, India, and the Middle East, implying the necessity of additional adaptation measures. By 2100, about 51·8% of global climate change mitigation costs could be offset by economic benefits from reduced labour productivity losses. Cumulatively, about 17·0% of climate change mitigation costs could be offset by the economic benefits between 2020 and 2100, when using a 2% social discounting rate. The costs and benefits of climate change mitigation will be distributed highly unevenly across regions due to their varying climate zones and economic structures. Regions with benefits from reduced productivity losses higher than mitigation costs are mainly low-latitude and tropical regions with lower income and lower emissions, such as southeast Asia, Brazil, and Mexico. More than half the climate change mitigation costs could be offset by the economic benefits by 2100 for the world's largest emitters, including the USA, China, the EU, and India. Low benefit-cost ratios are expected in economies that rely on fossil fuels, such as Canada, Russia, and the Middle East.Although pledging carbon neutrality implies radical changes to most economies, substantial health and economic gains can be achieved by reduced heat-related labour productivity loss, even without accounting for other benefits. The benefit-cost analysis in this study shows the potential for choosing more stringent climate change mitigation pathways in some regions. Regions with low benefit-cost ratios need to restructure their economies to reduce mitigation costs as well as losses from declined fossil fuel exports.National Natural Science Foundation of China, Tsinghua-Toyota Joint Research Fund, the Wellcome Trust, Tsinghua University-China Three Gorges Corporation Joint Research Center for Climate Governance Mechanism and Green Low-carbon Transformation Strategy, the National Research Foundation, Prime Minister's Office, Singapore (Campus for Research Excellence and Technological Enterprise [CREATE] programme), and the Global Energy Interconnection Development and Coorperation Organization.

Our paper, which is the first historical study about heat injuries in Singapore, seeks to situate the Singapore Armed Forces’ (SAF) history of heat stress management policies within the national context. Firstly, we observe that since the late 1970s, a research-driven approach has been adopted by the SAF’s military medical leaders to formulate a range of policies to address the Forces’ high incidence of heat injuries. This has resulted in the introduction of SAF-wide training measures, and the assembling of local scientific research expertise, which has led to a sharp reduction in heat injury incidence from the 1980s to 2000s. Through this, the SAF sought to demonstrate that its heat stress mitigation measures made the Singapore military ‘heat proof’. Secondly, the state shaped a soldier safety agenda in the late 2000s on the back of an increasing emphasis on safety and the transformation of the SAF into a highly-educated and technologically-sophisticated force. This meant a shift towards concern about the welfare of every soldier, particularly through the state’s drive to eradicate all training-related deaths. Accordingly, the SAF medical military leaders responded to the state’s safety agenda by introducing heat stress management research and policies that were oriented towards the target of eradicating deaths due to heat stress. This policy and research direction, as such, has been strongly guided by the state’s safety agenda and utilised to demonstrate to the public that all efforts have been taken to comprehensively mitigate the risks of heat.

Epidemiological studies have reported the association between extreme temperatures and adverse reproductive effects. However, the susceptible period of exposure during pregnancy remains unclear. This study aimed to assess the impact of extreme temperature on the stillbirth rate. We performed a time-series analysis to explore the associations between temperature and stillbirth with a distributed lag nonlinear model. A total of 22,769 stillbirths in Taiwan between 2009 and 2018 were enrolled. The mean stillbirth rate was 11.3 ± 1.4 per 1000 births. The relative risk of stillbirth due to exposure to extreme heat temperature (> 29 °C) was 1.18 (95% CI 1.11, 1.25). Pregnant women in the third trimester were most susceptible to the effects of extreme cold and heat temperatures. At lag of 0–3 months, the cumulative relative risk (CRR) of stillbirth for exposure to extreme heat temperature (29.8 °C, 97.5th percentile of temperature) relative to the optimal temperature (21 °C) was 2.49 (95% CI: 1.24, 5.03), and the CRR of stillbirth for exposure to extreme low temperature (16.5 °C, 1st percentile) was 1.29 (95% CI: 0.93, 1.80). The stillbirth rate in Taiwan is on the rise. Our findings inform public health interventions to manage the health impacts of climate change.

There are limited data on the fluid balance characteristics and fluid replenishment behaviors of high-performance adolescent athletes. The heterogeneity of hydration status and practices of adolescent athletes warrant efficient approaches to individualizing hydration strategies. This study aimed to evaluate and characterize the hydration status and fluid balance characteristics of high-performance adolescent athletes and examine the differences in fluid consumption behaviors during training. In total, 105 high-performance adolescent athletes (male: 66, female: 39, age 14.1 ± 1.0 y) across 11 sports had their hydration status assessed on three separate occasions—upon rising and before a low and a high-intensity training session (pre-training). The results showed that 20–44% of athletes were identified as hypohydrated, with 21–44% and 15–34% of athletes commencing low- and high-intensity training in a hypohydrated state, respectively. Linear mixed model (LMM) analyses revealed that athletes who were hypohydrated consumed more fluid (F (1.183.85)) = 5.91, (p = 0.016). Additional K-means cluster analyses performed highlighted three clusters: “Heavy sweaters with sufficient compensatory hydration habits,” “Heavy sweaters with insufficient compensatory hydration habits” and “Light sweaters with sufficient compensatory hydration habits”. Our results highlight that high-performance adolescent athletes with ad libitum drinking have compensatory mechanisms to replenish fluids lost from training. The approach to distinguish athletes by hydration characteristics could assist practitioners in prioritizing future hydration intervention protocols.

We would like to thank Dr. Charles Dumke for taking interest in our recent publication [...]

Purpose: To investigate the effects of short-term, high-intensity interval-training (HIIT) heat acclimation (HA). Methods: Male cyclists/triathletes were assigned into either an HA (n = 13) or a comparison (COMP, n = 10) group. HA completed 3 cycling heat stress tests (HSTs) to exhaustion (60% Wmax; HST1, pre-HA; HST2, post-HA; HST3, 7 d post-HA). HA consisted of 30-min bouts of HIIT cycling (6 min at 50% Wmax, then 12 × 1-min 100%-Wmax bouts with 1-min rests between bouts) on 5 consecutive days. COMP completed HST1 and HST2 only. HST and HA trials were conducted in 35°C/50% relative humidity. Cycling capacity and physiological and perceptual data were recorded. Results: Cycling capacity was impaired after HIIT HA (77.2 [34.2] min vs 56.2 [24.4] min, P = .03) and did not return to baseline after 7 d of no HA (59.2 [37.4] min). Capacity in HST1 and HST2 was similar in COMP (43.5 [8.3] min vs 46.8 [15.7] min, P = .54). HIIT HA lowered resting rectal (37.0°C [0.3°C] vs 36.8°C [0.2°C], P = .05) and body temperature (36.0°C [0.3°C] vs 35.8°C [0.3°C], P = .03) in HST2 compared with HST1 and lowered mean skin temperature (35.4°C [0.5°C] vs 35.1°C [0.3°C], P = .02) and perceived strain on day 5 compared with day 1 of HA. All other data were unaffected. Conclusions: Cycling capacity was impaired in the heat after 5 d of consecutive HIIT HA despite some heat adaptation. Based on data, this approach is not recommended for athletes preparing to compete in the heat; however, it is possible that it may be beneficial if a state of overreaching is avoided.

Purpose:To determine if the Physiological Strain Index (PSI), in original or modified form, can evaluate heat strain on a 0–10 scale, in trained and heat-acclimatized men undertaking a competitive half-marathon run in outdoor heat.Methods:Core (intestinal) temperature (TC) and heart rate (HR) were recorded continuously in 24 men (mean [SD] age = 26 [3] y, VO2peak = 59 [5] mL·kg·min−1). A total of 4 versions of the PSI were computed: original PSI with upper constraints of TC 39.5°C and HR 180 beats·min−1(PSI39.5/180) and 3 modified versions of PSI with each having an age-predicted maximal HR constraint and graded TC constraints of 40.0°C (PSI40.0/PHRmax), 40.5°C (PSI40.5/PHRmax), and 41.0°C (PSI41.0/PHRmax).Results:In a warm (26.1–27.3°C) and humid (79–82%) environment, all runners finished the race asymptomatic in 107 (10) (91–137) min. Peak TC and HR were 39.7°C (0.5°C) (38.5–40.7°C) and 186 (6) (175–196) beats·min−1, respectively. In total, 63% exceeded TC 39.5°C, 71% exceeded HR 180 beats·min−1, and 50% exceeded both of the original PSI upper TC and HR constraints. The computed heat strain was significantly greater with PSI39.5/180than all other methods (P 10 was observed in 63% of runners with PSI39.5/180, 25% for PSI40.0/PHRmax, 8% for PSI40.5/PHRmax, and 0% for PSI41.0/PHRmax.Conclusions:The PSI was able to quantify heat strain on a 0–10 scale in trained and heat-acclimatized men undertaking a half-marathon race in outdoor heat, but only when the upper TC and HR constraints were modified to 41.0°C and age-predicted maximal HR, respectively.

We would like to thank Dr. Charles Dumke for taking interest in our recent publication [...].

Heat stress caused by climate change and heat-related labor productivity losses have become global concerns. Estimating the economic impacts of heat stress is of great significance for employers, as well as sectoral and national policy makers who are searching for solutions to reduce productivity losses. As the value of economic impacts are sensitive to the research methodologies, we conducted a systematic review of published literature on the methodologies and results of economic impacts of heat on labor productivity. Four methods were summarized: the human capital (HC) method, the econometric method (EM), the input–output (IO) method, and the computable general equilibrium (CGE) model. Considering adaptation measures, global economic losses due to heat-related labor productivity losses are projected to range from 0.31% (0.14–0.5%, RCP2.6) to 2.6% (1.4–4%, RCP8.5) of global GDP in 2100. The published studies found that large economic losses occurred mainly in South and Southeast Asia, Sub-Saharan Africa, and Central America. Owing to different methodologies and considerations of adaptation measures, the disparities of results within the same area at a given time can be as high as 7.4-fold. We summarized the knowledge gaps in existing studies and proposed new directions to provide more targeted and reliable results for policy makers.

Sustainable methods are required to reduce the risks of thermal strain and heat-related illness without exacerbating greenhouse gas emissions. We investigated the effects of sun-shade use on safe heat exposure limit on a sunny summer day using historical climate data in Japan. We simulated a heat-acclimatised person standing at rest (metabolic heat production, 70 W·m

INTRODUCTION A physiological profiling study was done to evaluate thermal strain as well as fluid and electrolyte balances on heat-acclimatised men performing a 72-km route march in a field setting. METHODS 38 male soldiers (age range 18-23 years) participated in the study, as part of a cohort that marched for 72 km, with loads for about 26 hours. Core temperature and heart rate sensors were used for the duration of the march. Fluid and food intake and output were monitored for the duration of the march. Blood samples were taken one day before the march (pre-march), immediately after the march before they had any opportunity to recover (Post 1) and on the 15th day after the march to ascertain recovery (Post 2) to assess fluid and electrolyte profiles. RESULTS Mean core temperature was within safe limits, ranging from 37.1 to 38.1°C throughout the march. There was an average overall decrease in serum sodium levels, a decline in serum sodium concentration in 28 participants and three instances of hyponatraemia (serum sodium concentration < 135 mmol/L). CONCLUSION Our study found low thermal strain among heat-acclimatised individuals during a 72-km route march. However, there was an average overall decrease in serum sodium levels, even when the participants were allowed to drink ad libitum. Challenges of exercise-associated hyponatraemia during prolonged activities remain to be addressed.

Aim: The purpose of this study was to evaluate hydration status, fluid intake, sweat rate, and sweat sodium concentration in recreational tropical native runners. Methods: A total of 102 males and 64 females participated in this study. Participants ran at their self-selected pace for 30–100 min. Age, environmental conditions, running profiles, sweat rates, and sweat sodium data were recorded. Differences in age, running duration, distance and pace, and physiological changes between sexes were analysed. A p-value cut-off of 0.05 depicted statistical significance. Results: Males had lower relative fluid intake (6 ± 6 vs. 8 ± 7 mL·kg−1·h−1, p &lt, 0.05) and greater relative fluid balance deficit (−13 ± 8 mL·kg−1·h−1 vs. −8 ± 7 mL·kg−1·h−1, p &lt, 0.05) than females. Males had higher whole-body sweat rates (1.3 ± 0.5 L·h−1 vs. 0.9 ± 0.3 L·h−1, p &lt, 0.05) than females. Mean rates of sweat sodium loss (54 ± 27 vs. 39 ± 22 mmol·h−1) were higher in males than females (p &lt, 0.05). Conclusions: The sweat profile and composition in tropical native runners are similar to reported values in the literature. The current fluid replacement guidelines pertaining to volume and electrolyte replacement are applicable to tropical native runners.

The current understanding of ambient temperature and its link to the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. The objective of this study was to explore the environmental and climatic risk factors for SARS-CoV-2. For this study, we analyzed the data at the beginning of the outbreak (from 20 January to 31 March 2020) to avoid the influence of preventive or control measures. We obtained the number of cases and deaths due to SARS-CoV-2, international tourism, population age, universal health coverage, regional factors, the SARS-CoV-2 testing rate, and population density of a country. A total of 154 countries were included in this study. There were high incidence rates and mortality risks in the countries that had an average ambient temperature between 0 and 10 °C. The adjusted incidence rate for temperatures between 0 and 10 °C was 2.91 (95% CI 2.87–2.95). We randomly divided the data into a training set (80% of data) for model derivation and a test set (20% of data) for validation. Using a random forest statistical model, the model had high accuracy for predicting the high epidemic status of a country (ROC = 95.5%, 95% CI 87.9–100.0%) in the test set. Population age, temperature, and international tourism were the most important factors affecting the risk of SARS-CoV-2 in a country. An understanding the determinants of the SARS-CoV-2 outbreak can help to design better strategies for disease control. This study highlights the need to consider thermal effect in the prevention of emerging infectious diseases.

The pandemic has been afflicting the planet for over a year and from the occupational point of view, healthcare workers have recorded a substantial increase in working hours. The use of personal protective equipment (PPE), necessary to keep safe from COVID-19 increases the chances of overheating, especially during the summer seasons which, due to climate change, are becoming increasingly warm and prolonged. A web survey was carried out in Italy within the WORKLIMATE project during the summer and early autumn 2020. Analysis of variance (ANOVA) was used to evaluate differences between groups. 191 questionnaires were collected (hospital doctor 38.2%, nurses 33.5%, other healthcare professionals 28.3%). The impact of PPE on the thermal stress perception declared by the interviewees was very high on the body areas directly covered by these devices (78% of workers). Workers who used masks for more than 4 h per day perceived PPE as more uncomfortable (p &lt, 0.001) compared to the others and reported a greater productivity loss (p &lt, 0.001). Furthermore, the study highlighted a high perception of thermal stress among healthcare workers that worn COVID-19-PPE and this enhances the need for appropriate heat health warning systems and response measures addressed to the occupational sector.

The COVID-19 pandemic started in the cold months of the year 2020 in the Northern hemisphere. Concerns were raised that the hot season may lead to additional problems as some typical interventions to prevent heat-related illness could potentially conflict with precautions to reduce coronavirus transmission. Therefore, an international research team organized by the Global Health Heat Information Network generated an inventory of the specific concerns about this nexus and began to address the issues. Three key thermal and covid-19 related topics were highlighted: 1) For the general public, going to public cool areas in the hot season interferes with the recommendation to stay at home to reduce the spread of the virus. Conflicting advice makes it necessary to revise national heat plans and alert policymakers of this forecasted issue. 2) For medical personnel working in hot conditions, heat strain is exacerbated due to a reduction in heat loss from wearing personal protective equipment to prevent contamination. To avoid heat-related injuries, medical personnel are recommended to precool and to minimize the increase in body core temperature using adopted work/rest schedules, specific clothing systems, and by drinking cold fluids. 3) Fever, one of the main symptoms of COVID-19, may be difficult to distinguish from heat-induced hyperthermia and a resting period may be necessary prior to measurement to avoid misinterpretation. In summary, heat in combination with the COVID-19 pandemic leads to additional problems; the impact of which can be reduced by revising heat plans and implementing special measures attentive to these compound risks.

Research on viral outbreaks at the pandemic scale responds to heightened social urgency and the need to expedite scientific discovery from the “bench” to the “bedside” to the wider population. We sought to better understand translational research within the context of pandemics, both historical and present day, by tracking publication trends in the immediate aftermath of virus outbreaks. We used a blend of natural language processing (NLP), social network analysis and human annotation approaches to analyze the 85,663 articles in the COVID-19 Open Research Dataset (CORD-19). We found stable and repeated characteristics throughout subsets of peer-reviewed published literature corresponding to seven different viral outbreaks over the last several decades. Three distinct groups or “neighborhoods” recurred across all of the model networks – (1) bench science, (2) clinical treatments, and (3) broader public health trends. Notably, in each historical virus model, small “bridge” nodes representing translational research connect the three otherwise disconnected neighborhoods. These bridging studies embody research convergence by both integrating the vocabulary and methods of different disciplines and bodies of previous work and by citing other papers beyond their narrow field. In the case of COVID-19, the literature continues to evolve apace along with the virus, and we can witness the phases of response unfold as the science progresses. This study demonstrates how the different sectors of biomedical research respond independently to public health emergencies and how translational research can facilitate greater information synthesis and exchange between disciplinary silos.

COVID 19 is a major planetary emergency and intense workloads and the potential heat stress create critical conditions for healthcare workers. A web survey was carried out in Italy during summer 2020 as part of WORKLIMATE project with the aim of assessing the interaction between Personal Protective Equipment (PPE) and heat stress in healthcare workers. Preliminary results on 191 questionnaires show an increase of heat stress perception in the areas covered by PPE determining symptoms such as thirst, sweating and general distress. This information could be useful to allow preventive measure to safeguard health and productivity of these workers.

Using palatable fluids to enhance drinking in athletes who display insufficient compensatory hydration behaviour may mitigate the risks of hypohydration and performance deficits. However, it is unclear whether flavour can independently enhance fluid consumption. This study examined the effects of a colourless, artificially sweetened flavoured water (FW), without carbohydrates and with negligible amounts of sodium, compared to plain water (W) on fluid consumption in male collegiate basketball players in a practical game setting. Eighteen male basketball players (age 23.1 ± 1.3 years) played a 3v3 basketball small-sided game. The players were randomly assigned to consume either FW or W. Pre-game urine-specific gravity, fluid consumption, body mass, and hedonic taste perceptions were assessed. Basketball performance was analysed through notational analysis. Ratings of perceived exertion and thirst were recorded at pre-, post-game, and at each rest period. Heart rate was recorded throughout the gameplay. Despite significantly higher hedonic ratings for FW than W (6.78 ± 0.83 vs. 5.56 ± 1.33, p = 0.033, d = 1.36), there were no significant differences in fluid consumption (1083 ± 32 mL vs. 1421 ± 403 mL, p = 0.068, d = 0.92). Our result highlighted that using palatable fluids as a strategy to increase fluid consumption during high-intensity gameplay in the heat may not be effective if used without carbohydrates and electrolytes. Practitioners could consider both fluid palatability and composition in establishing a hydration plan for athletes.

The Lancet Countdown is an international collaboration that independently monitors the health consequences of a changing climate. Publishing updated, new, and improved indicators each year, the Lancet Countdown represents the consensus of leading researchers from 43 academic institutions and UN agencies. The 44 indicators of this report expose an unabated rise in the health impacts of climate change and the current health consequences of the delayed and inconsistent response of countries around the globe—providing a clear imperative for accelerated action that puts the health of people and planet above all else.\ud \ud The 2021 report coincides with the UN Framework Convention on Climate Change 26th Conference of the Parties (COP26), at which countries are facing pressure to realise the ambition of the Paris Agreement to keep the global average temperature rise to 1·5°C and to mobilise the financial resources required for all countries to have an effective climate response. These negotiations unfold in the context of the COVID-19 pandemic—a global health crisis that has claimed millions of lives, affected livelihoods and communities around the globe, and exposed deep fissures and inequities in the world's capacity to cope with, and respond to, health emergencies. Yet, in its response to both crises, the world is faced with an unprecedented opportunity to ensure a healthy future for all.

This study investigated the efficacy of ingesting an oral rehydration solution (DD) that has a high electrolyte concentration after exercise on fluid balance and cycling performance in comparison with a sports drink (SD) and water (WA). Nine healthy males aged 24 &plusmn, 2 years (mean &plusmn, SD), with peak oxygen uptake (VO2 peak) 55 &plusmn, 6 mL&middot, kg&minus, 1&middot, min&minus, 1 completed three experimental trials in a randomised manner ingesting WA, SD (carbohydrates: 62 g&middot, L&minus, 1, sodium: 31 &plusmn, 3 mmol&middot, 1) or DD (carbohydrates: 33 g&middot, 1, sodium: 60 &plusmn, 1). On all trials, fluid was ingested during 75 min cycling at 65% VO2 peak (temperature: 30.4 &plusmn, 0.3 &deg, C, relative humidity: 76 &plusmn, 1%, simulated wind speed: 8.0 &plusmn, 0.6 m&middot, s&minus, 1) and during 2 h of recovery (temperature: 23.0 &plusmn, 1.0 &deg, C, relative humidity: 67 &plusmn, 2%), with the total volume equivalent to 150% of sweat loss during the ride. A 45 min pre-load cycling time trial at a 65% VO2 peak followed by a 20 km time trial was conducted after a further 3 h of recovery. Fluid retention was higher with DD (30 &plusmn, 15%) than WA (&minus, 4 &plusmn, 19%, p &lt, 0.001) and SD (10 &plusmn, 15%, p = 0.002). Mean ratings of palatability were similar among drinks (WA: 4.25 &plusmn, 2.60, SD: 5.61 &plusmn, 1.79, DD: 5.40 &plusmn, 1.58, p = 0.33). Although time trial performance was similar across all three trials (WA: 2365 &plusmn, 321 s, SD: 2252 &plusmn, 174 s, DD: 2268 &plusmn, 184 s, p = 0.65), the completion time was faster in eight participants with SD and seven participants with DD than with WA. Comparing SD with DD, completion time was reduced in five participants and increased in four participants. DD was more effective at restoring the fluid deficit during recovery from exercise than SD and WA without compromising the drink&rsquo, s palatability with increased sodium concentration. Most individuals demonstrated better endurance exercise time trial performance with DD and SD than with WA.

Global climate is changing as a result of anthropogenic warming, leading to higher daily excursions of temperature in cities. Such elevated temperatures have great implications on human thermal comfort and heat stress, which should be closely monitored. Current methods for heat exposure assessments (surveys, microclimate measurements, and laboratory experiments), however, present several limitations: measurements are scattered in time and space and data gathered on outdoor thermal stress and comfort often does not include physiological and behavioral parameters. To address these shortcomings, Project Coolbit aims to introduce a human-centric approach to thermal comfort assessments. In this study, we propose and evaluate the use of wrist-mounted wearable devices to monitor environmental and physiological responses that span a wide range of spatial and temporal distributions. We introduce an integrated wearable weather station that records (a) microclimate parameters (such as air temperature and humidity), (b) physiological parameters (heart rate, skin temperature and humidity), and (c) subjective feedback. The feasibility of this methodology to assess thermal comfort and heat stress is then evaluated using two sets of experiments: controlled-environment physiological data collection, and outdoor environmental data collection. We find that using the data obtained through the wrist-mounted wearables, core temperature can be predicted non-invasively with 95 percent of target attainment within ±0.27 °C. Additionally, a direct connection between the air temperature at the wrist (T a,w ) and the perceived activity level (PAV) of individuals was drawn. We observe that with increased T a,w , the desire for physical activity is significantly reduced, reaching ‘Transition only’ PAV level at 36 °C. These assessments reveal that the wearable methodology provides a comprehensive and accurate representation of human heat exposure, which can be extended in real-time to cover a large spatial distribution in a given city and quantify the impact of heat exposure on human life.