Exertional Heat Illness Research Articles

Playing on natural or artificial turf sports field? Assessing heat stress of children, young athletes, and adults in Hong Kong

Exercising in an unusually hot environment may aggravate exertional heat illness. Turf material significantly affects the microenvironment and heat-stress sensation of sports-field users. However, the difference in human- biometeorological effects between different sports-field turf materials demands further investigation. This study compared artificial (AT) with natural turf (NT) fields, investigating three age groups (children, young athletes, and adults), two physical activities (playing soccer and walking), and three heat stress indicators (HI, Heat Index; WBGT, Wet Bulb Globe Thermometer; and COMFA, COMfort FormulA). The results showed heat-stress underestimation by HI and WBGT. In contrast, COMFA, incorporating comprehensive environmental and human physiological parameters, provided a more targeted and reliable heat-stress assessment. COMFA indicated a longer heat-stress duration exercising at AT than NT. Compared to NT, children suffered a 24% longer “Extreme danger” duration at AT in sunny daytime. The AT-NT difference in human-biometeorological effect was limited concerning human convection, evaporation, metabolic heat, and emitted longwave radiation, but was considerable in human absorbed radiation. AT had lower albedo than NT, hence field users absorbed more upward longwave radiation but less upward shortwave radiation, highlighting important control by the radiant environment. NT sports fields are recommended for a healthy outdoor thermal environment, especially for children.

Status of US Emergency Medical Service Protocols Regarding Pre-Transfer Cooling for Exertional Heat Stroke

Objective: Exertional heat stroke (EHS) is a significant cause of morbidity and mortality in athletes and active individuals. In the field, initial management of exertional heat illness is based on rapid whole-body cooling. Cold-water immersion (CWI) is considered the superior cooling modality for EHS treatment. However, there often is a disconnect between the sports medicine community and the emergency medical service (EMS) community. Well-written emergency action plans may fail if EMS protocols do not allow for CWI in initial management. This is the first study to look at the current national EMS protocols regarding prehospital management of EHS. The purpose of our study was to assess the status of heat illness protocols regarding CWI for EHS in all 50 states plus Washington, DC. Methods: An internet search was performed to find EHS protocols. Statewide protocols were preferred. Several parameters were recorded for each protocol including whether: 1) CWI was the recommended cooling treatment for EHS and 2) CWI was explicitly permitted to be completed prior to transportation.Results: We found nine of the 51 protocols, or 17.6%, explicitly recommended CWI and 11 of the 51, or 21.6%, specifically instructed EMS personnel to complete CWI or cooling methods prior to transport. However, six protocols, or 11.8%, provided the recommendation instructing some variation of the phrase “do not delay transport to cool the patient.”Conclusion: Despite the medical literature endorsing CWI as the most effective treatment modality in a prehospital setting for exertional heat illness, EMS protocols largely fail to reflect this which leads to mismanagement and inadequate care of EHS patients. While CWI is not always available, all EMS protocols should include a systematic practical guideline for a heat illness patient when employing cooling treatment with an emphasis on CWI when available as the preferred treatment technique for EHS and the concept of “cool first, transport second.”

Emergency Action Planning in School-Based Athletics: A Systematic Review.

IntroductionA significant number of preventable catastrophic injuries occur in secondary school athletics. Compliance to Emergency Action Plan (EAP) recommendations is not well documented. The purpose of this systematic review was to identify compliance to EAP recommendations, access to an athletic trainer (AT) and automated external defibrillator (AED), and current legislative mandates in school-based athletics.MethodsElectronic databases were searched to identify articles that met criteria for inclusion. Studies in English that focused on adoption, implementation, or compliance with EAPs or other national guidelines pertaining to athlete health were eligible for inclusion. Quality and validity were examined in each article and data were grouped based on outcome measures.ResultsOf 12,906 studies, 21 met the criteria for inclusion and full text review. Nine studies demonstrated EAP adoption rates ranging from 55% – 100%. Five studies found that EAPs were rehearsed and reviewed annually in 18.2% – 91.6% of schools that have an EAP. At total of 9.9% of schools were compliant with all 12 National Athletic Trainers Association (NATA) EAP guidelines. A total of 2.5% – 27.5% of schools followed NATA exertional heat illness guidelines and 50% – 81% of schools had access to an athletic trainer. In addition, 61% – 94.4% of schools had an AED available at their athletic venues. Four of 51 state high school athletic association member schools were required to meet best practice standards for EAP implementation, 7 of 51 for AED access, 8 of 51 for heat acclimation, and 3 of 51 for concussion management.ConclusionsThere was a wide range of EAP adoption and a low rate of compliance to EAP guidelines in U.S. schools. Barriers to EAP adoption and compliance were not well documented and additional research should aim to identify impeding and facilitating factors.

Behavioural adaptation: A review of adaptation to workplace heat exposure of kitchen workers with reference to gender differences in Durban

The article examines the gender disparities as women are at a greater risk to exertional heat illness that may go unreported in the industry, according to several reports. It is important to study the behavioural heat adaptations and prevalent behaviours for workers in order to understand the magnitude of the danger they face. Cooking is considered a safe occupation, but hazards certainly do exist and can represent a risk to the health and safety of the workers. Controls can be established to reduce the risk of illness. To attract and retain workers, the food service business must provide a good quality of life.Contribution: The study suggests how female workers in the catering establishments can adjust their behaviour to improve their experience at work. Are women more vulnerable to environmental parameters? Christian theology provides women equal status with men (Kategile 2020), however there are traces of androcentric aspects within the Bible. Women’s involvement in development is based on the theological premise that true development must have a holistic approach towards human development (Onwunta 2009). However, Sibani (2017) stated that the role of God or a creator of a religion, is always taken by a male and a woman’s place is in the household. The article conducts a comprehensive analysis of the literature on the various behavioural adaptation mechanisms used by kitchen staff to cope with heat exposure at work. Thermal tolerance variations are becoming more pronounced because of ethnicity and cultural differences. Health interventions and enhanced work performance are important objectives of workplace safety. Regulated heat in the workplace can be factored into the theory concerning the relationship between gender differences and contextual components. This would increase female food service workers’ understanding of thermal comfort, which is beneficial to productivity efficiency, worker satisfaction and well-being of workers.

The relationship between physiological and performance variables during a hot/humid international rugby sevens tournament

ABSTRACT To characterise physiological responses to competing in an international rugby sevens tournament played in hot/humid conditions, core temperature (Tc) and Tc predictors were collected from 11 elite men’s rugby sevens athletes competing in the Oceania sevens tournament in Suva, Fiji. Tc, body mass change, sweat electrolytes, playing minutes, total running distance, high speed running distance (HSD), psychrometric wet bulb temperature and exertional heat illness symptoms were collected pre, during and post games. Linear mixed-models were used to assess the effect of Tc predictors on post-game Tc, along with differences in Tc across measurement periods. Compared to baseline on both tournament days, mean Tc was higher during all between game (recovery) measures (all d >1.30, p <0.01). On both tournament days, eight athletes reached a post-game Tc >39.0°C, with several athletes reaching >39.0°C during warm-ups. Mean post-game Tc was related to playing minutes, total running distance, HSD, and post warm-up Tc (all p < 0.01). The Tc during warm-ups and games regularly exceeded those demonstrated to be detrimental to repeated sprint performance (> 39°C). Warm-up Tc represents the easiest predictor of post-game Tc to control via time/intensity modulation and the use of appropriate pre- and per-cooling strategies. Practitioners should be prepared to modulate warm-ups and other heat preparation strategies based on likely environmental conditions during hot/humid tournaments.

Factors Affecting Incidence Rate of Exertional Heat Illnesses: Analysis of 6 Years of High School Football Practices in North Central Florida

Background:Although experts have advocated for regionally specific heat safety guidelines for decades, guidelines have not been universally adopted.Purpose:To describe the rate and risk factors associated with exertional heat illness (EHI).Study Design:Descriptive epidemiology study.Methods:For a 3-month period (August-October) over 6 years (2013-2018), athletic trainers at 13 high schools in North Central Florida recorded varsity football practice time and length, wet-bulb globe temperature (WBGT), and incidences of EHI, including heat stroke, heat exhaustion, and heat syncope.Results:Athletes sustained 54 total EHIs during 163,254 athlete-exposures (AEs) for the 3-month data collection periods over 6 years (incidence rate [IR], 3.31 /10,000 AEs). Heat exhaustion accounted for 59.3% (32/54), heat syncope 38.9% (21/54), and heat stroke 1.9% (1/54) of all EHIs recorded. Of the EHIs, 94.4% (51/54) were experienced within the first 19 practices. The first 19 practices had an IR of 7.48 of 10,000 AEs, and the remaining 44 practices had an IR of 0.32 of 10,000 AEs, demonstrating that the risk of EHI for practices 1 to 19 was 23.7 times that of the remaining practices. When comparing morning to afternoon practices, 35.2% (19/54) EHI incidents occurred during morning practices. The risk of EHI during practices with WBGT >82°F (27.8°C) was 3.5 times that of practices with WBGT <82°F.Conclusion:In the current study, the risk of EHI was greatest in the first 19 practices of the season and during practices with WBGT >82°F. As modifiable risk factors for EHI, increased vigilance and empowerment to adhere to acclimatization guidelines can mitigate EHI risk. Health care providers must continue to advocate for implementation of regulations and the authority to make decisions to ensure patient safety.

ACSM Expert Consensus Statement on Exertional Heat Illness: Recognition, Management, and Return to Activity.

Exertional heat stroke (EHS) is a true medical emergency with potential for organ injury and death. This consensus statement emphasizes that optimal exertional heat illness management is promoted by a synchronized chain of survival that promotes rapid recognition and management, as well as communication between care teams. Health care providers should be confident in the definitions, etiologies, and nuances of exertional heat exhaustion, exertional heat injury, and EHS. Identifying the athlete with suspected EHS early in the course, stopping activity (body heat generation), and providing rapid total body cooling are essential for survival, and like any critical life-threatening situation (cardiac arrest, brain stroke, sepsis), time is tissue. Recovery from EHS is variable, and outcomes are likely related to the duration of severe hyperthermia. Most exertional heat illnesses can be prevented with the recognition and modification of well-described risk factors ideally addressed through leadership, policy, and on-site health care.

Exertional heat illnesses in marching band artists: a case series.

Marching band (MB) artists frequently spend many hours engaged in outdoor physical activity. Anecdotal evidence and small studies have indicated that MB artists do experience heat-related health problems. Yet, unlike athletes, military personnel, or workers, there is very little research on heat-related hazards among this unique population. Here, we seek to understand the incidence and circumstances under which exertional heat illnesses (EHIs) occur among MB artists over a 31-year period (1990-2020) across the USA. Using an on-line news dataset, we identified 34 separate events and at least 393 total EHIs. Heat syncope (~ 55%) and heat exhaustion (~ 44%) comprised the majority of EHIs, although a small number of exertional heat stroke cases were also reported. EHIs were reported in all types of MB activities with ~ 32% during rehearsal, ~ 29% during parades, ~ 21% during competition, and ~ 15% during a performance. Also, the vast majority of events occurred with high school (~ 88%) marching bands. Finally, EHIs overwhelmingly occurred when the weather was unusually hot by local conditions. In light of these findings, we emphasize the need for MB specific heat polices that incorporate weather-based activity modification, acclimatization, education about EHIs, and access to on-site medical professionals.

An investigation into environmental variables influencing post-race exertional heat illness in thoroughbred racehorses in temperate eastern Australia.

Exertional heat illness (EHI) is a syndrome that occurs when metabolic heat production from muscular contraction exceeds the rate at which it can be dissipated. Core body temperature rises to critical levels, causing hyperthermia and central nervous system dysfunction. Best practice for the prevention of EHI centres around early detection, rapid response and aggressive cooling. Advance planning enables risk mitigation measures. The more that is known about EHI in horses, the better prepared those in the positions of responsibility can be to anticipate events in which the risk of EHI may be elevated. This prospective, observational study investigated environmental risk factors associated with the occurrence of EHI. From 2014 to 2018, the number of horses exhibiting the symptoms of post-race EHI was recorded at 73 convenience sampled race meetings. Of the 4809 starters, the signs of EHI were recorded for 457. Thermal environmental data were measured and included ambient temperature, radiant heat, vapor pressure (humidity) and wind speed (WS). Mixed linear regression models were computed to assess the associations between the occurrence and incidence of post-race EHI and the four thermal environmental variables. The analysis showed that vapor pressure and WS had the largest effects on the occurrence of post-race EHI. The major limitations were that the race meetings selected were convenience sampled according to attendance by the first author and individual horse data were not available. EHI is influenced by a complex interaction of independently acting environmental variables, but warm, windless, humid days are most likely to result in the cases of EHI.

Modifications Of Exertional Heat Illness Policies In Us High School Athletics Over An Academic Year

PURPOSE: To evaluate the modifications of Exertional Heat Illness (EHI) policies in United States (US) high schools over a period of one academic year (Fall to Spring) as reported by athletic trainers (ATs). METHODS: An 11-item pre-validated questionnaire was developed using the National Athletic Trainers’ Association Position Statement on EHI. ATs at high schools throughout the US were invited (via email or social media platforms) to complete an online questionnaire related to their school’s written EHI policies (yes/no written policy) at two time points (Fall 2018 and Spring 2019). A total of 105 ATs (female = 59.6%) employed at high schools (with a majority located in Southeast = 37.1%, school size = 1133 ± 935 students) completed the questionnaire at both time points. Data were aggregated and summarized using frequencies. Differences in modifications between time points were assessed using McNemar’s tests (P < 0.05). RESULTS: The proportion of ATs reporting the existence of a policy for the prevention and management of EHI was significantly higher in the Spring (75.7%) than in the preceding Fall (66.0%, p = 0.033). Further, the proportion of schools reporting the component “requires a cold-water immersion tub to be set up (including: filled with water, ice chests nearby) during warm weather activities)” was significantly higher in the Spring (72.6%) compared to the Fall (58.1%, p = 0.039). No other modifications in EHI policies were observed (p > 0.05, Table 1). CONCLUSION: Findings indicate that written EHI policies are not comprehensively and uniformly adopted at the start of the school year and adaptations appear to be marginal through the year. Intervention efforts targeted at improving written policies during the summer break may be warranted as EHI rates are highest in pre-season (i.e., Fall) practices.

Reply

Dear Editor:We appreciate the opportunity to respond to the letter about our investigation of age, sex, environmental conditions, and the incidence of exertional heat stroke (EHS) in a warm-weather road race.1 The letter author raises some points that allow us to further expand on our findings and, we hope, provide adequate context for his concerns.Overall, in examining the implications of this investigation, we appear to diverge from the author of the letter on a key point. He argues that EHS is preventable. Although every case of EHS is theoretically preventable, the large numbers of people with a variety of individual risk factors exercising in warm environments make total prevention nearly impossible. In addition to running road races, large-scale events involving exercise, such as military basic training,2 are subject to similar concerns regarding exertional heat illnesses despite comprehensive prevention efforts. However, we reiterate that data from this very race indicated that mortality from EHS did appear to be preventable with appropriate treatment.3The purpose of this investigation was to examine the factors that influenced the incidence of EHS on a population level. Furthermore, we sought to identify the factors that medical teams and race organizers might be able to consider before the road race to help determine the staff and supplies needed to appropriately treat patients with EHS. In our discussion, we fully acknowledged that EHS risk is multifactorial and consists of both intrinsic and extrinsic factors.4 However, the individual factors of the participants in running road races cited by the letter author (fitness, heat acclimatization, adiposity, and exertional intensity) are unknown and would likely require advanced laboratory techniques to ascertain. Even if these data were available for the cases presented, the utility of these analyses for onsite medical providers is limited. The mechanistic insights the author of the letter tried to glean from the presented data are beyond the scope of these data.Several times, the letter author referenced our findings, saying that males and youth were found to be at a higher risk of EHS. Throughout the paper, we referred to the results as applying to “younger runners,” not “youth,” and further clarified in the conclusion that these results primarily applied to runners aged 19 to 39 years. We made this distinction for many of the reasons the author of the letter stated, including the fact that the physiological and behavioral circumstances of individuals under the age of 18 participating in this race were unique.The letter author denoted several factors that may play a role in children having altered susceptibility to EHS. He correctly indicated that an altered body mass-to-surface area ratio did not solely explain the altered risk in youth individuals, and it is clear from his review that a description of the nuances of this risk extends beyond what is included in our manuscript. Runners under the age of 14 accounted for only 2.4% of race participants and 2.6% of patients with EHS. However, we would caution the author to avoid comparing EHS- and heat-related deaths (which include nonexertional cases); the mechanisms and causes of these conditions are clearly disparate.Finally, the author of this letter highlighted the claim that “only younger age accounted for an increased incidence of EHS,” yet we would like to stress that this statement was taken out of context: the other part of that sentence reads, “However, when sex was considered with age and WBGT [wet bulb globe temperature]. . .” We did not characterize age as the sole risk factor for EHS but rather our data supported that, of those variables we could study, age did statistically explain the greatest variance in EHS incidence.We conclude by emphasizing that our findings were epidemiologic in nature. Many factors influence an individual's susceptibility to EHS; by examining the patterns of EHS incidence in events such as the Falmouth Road Race, we can observe trends that either allow researchers to study these mechanisms in controlled environments or establish reference incidences for medical providers. We agree with the letter author's recommendations to increase community collaboration and minimize the risk globally for all runners using the precautions listed.

Exercise hyperthermia induces greater changes in gastrointestinal permeability than equivalent passive hyperthermia.

Hyperthermia and exertional heat illness increase gastrointestinal (GI) permeability, although whether the latter is only via hyperthermia is unclear. The aim of this pilot study was to determine whether different changes in GI permeability, characterized by an increased plasma lactulose:rhamnose concentration ratio ([L:R]), occurred in exercise hyperthermia in comparison to equivalent passive hyperthermia. Six healthy adult male participants (age 25 ± 5 years, mass 77.0 ± 6.7 kg, height 181 ± 6 cm, peak oxygen uptake [V·O2peak] 48 ± 8 ml.kg−1.min−1) underwent exercise under hot conditions (Ex‐Heat) and passive heating during hot water immersion (HWI). Heart rate (HR), rectal temperature (TCORE), rating of perceived exertion (RPE), and whole‐body sweat loss (WBSL) were recorded throughout the trials. The L:R ratio, peak HR, change in HR, and change in RPE were higher in Ex‐Heat than HWI, despite no differences in trial duration, peak core temperature or WBSL. L:R was strongly correlated (p < 0.05) with HR peak (r = 0.626) and change in HR (r = 0.615) but no other variable. The greater L:R in Ex‐Heat, despite equal TCORE responses to HWI, indicates that increased cardiovascular strain occurred during exercise, and exacerbates hyperthermia‐induced GI permeability at the same absolute temperature.

Procedure for assessing patients referred to the UK’s military Heat Illness Clinic: a case series

IntroductionThe UK military operates a Heat Illness Clinic (HIC) to aid the return to exercise, training and occupational duty recommendations for individuals who have suffered exertional heat illness or heatstroke....

Effect of post-exercise muscle cooling on PGC-1α and VEGF mRNA expression in Thoroughbreds

Besides preventing exertional heat illness, muscle cooling can be a potential strategy to enhance exercise-training induced adaptations. This study aimed to examine the effects of post-exercise cooling on the mRNA expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and vascular endothelial growth factor (VEGF) in Thoroughbred skeletal muscle. Five Thoroughbred horses performed treadmill running until their pulmonary artery temperature reached 42 °C, followed by walking on the treadmill with no additional cooling (CONT) or muscle cooling with a shower using the tap water (26 °C, 0.4 l/s; COOL), for 30 min. Muscle biopsies were obtained before (PRE) and 3 h after exercise (3 Hr-REC) from the gluteus medius muscle. PGC-1α mRNA expression was elevated 3 h after exercise in both the CONT (PRE vs 3 Hr-REC: 1.0±0.1 vs 5.0±0.8,P&lt;0.01) and COOL (PRE vs 3 Hr-REC: 1.1±0.3 vs 6.6±0.9,P&lt;0.01) conditions; however, there was no difference between the two conditions at 3 h after exercise (P=0.17). VEGF mRNA expression was elevated 3 h after exercise in COOL (PRE vs 3 Hr-REC: 1.0±0.2 vs 2.2±0.2,P&lt;0.05) but not in CONT (PRE vs 3 Hr-REC: 1.0±0.1 vs 1.8±0.3,P=0.08). VEGF mRNA expression at 3 h after exercise was significantly negatively correlated with rectal temperature at the end of the 30-min cooling period (r = -0.65,P&lt;0.05). Our results suggest that the decline in body temperature after exercise may lead to greater expression of the key angiogenic gene in Thoroughbred horses.

Exertional Heat Illness: A Clinical and Evidence-Based Guide.

Exertional Heat Illness: A Clinical and Evidence-Based Guide.

Thermoregulatory Responses with Size-matched Simulated Torso or Limb Skin Grafts.

This study aimed to test the hypothesis that a simulated burn injury on the torso will be no more or less detrimental to core temperature control than on the limbs during uncompensable exercise-heat stress. Nine nonburned individuals (7 men, 2 women) completed the protocol. On separate occasions, burn injuries of identical surface area (0.45 ± 0.08 m2 or 24.4% ± 4.4% of total body surface area) were simulated on the torso or the arms/legs using an absorbent, vapor-impermeable material that impedes sweat evaporation in those regions. Participants performed 60 min of treadmill walking at 5.3 km·h-1 and a 4.1% ± 0.8% grade, targeting 6 W·kg-1 of metabolic heat production in 40.1°C ± 0.2°C and 19.6% ± 0.6% relative humidity conditions. Rectal temperature, heart rate, and perceptual responses were measured. Rectal temperature increased to a similar extent with simulated injuries on the torso and limbs (condition-by-time interaction, P = 0.86), with a final rectal temperature 0.9°C ± 0.3°C above baseline in both conditions. No differences in heart rate, perceived exertion, or thermal sensation were observed between conditions (condition-by-time interactions, P ≥ 0.50). During uncompensable exercise-heat stress, sized-matched simulated burn injuries on the torso or limbs evoke comparable core temperature, heart rate, and perceptual responses, suggesting that the risk of exertional heat illness in such environmental conditions is independent of injury location.

22 Comparison of post-exercise cooling methods in horses

Exertional heat illness (EHI) following strenuous exercise under hot and humid conditions can be detrimental in horses. Direct cooling after intense exercise is necessary to prevent EHI. Therefore, this study aimed to evaluate the efficacy of 3 cooling methods in horses post treadmill exercise. Five mature geldings were treadmill exercised on 3 consecutive weeks to determine the effect of 3 post-exercise cool-down methods (5 × 3 Latin square design). These methods were (i) no water application (W no ), (ii) cold water application only (W only ; pouring 30 L of cold water (6°C) every min for 6 min) and (iii) cold water application with scraping (W scraping ; cold water (6°C) application followed by scraping after each water application). After 6 min active cool-down phase, the horses were walked in-hand (walking phase) for 4 min and stood (standing phase) for 35 min. Central venous temperature (T CV ) and rectal temperature (T R ) were selected and measured simultaneously. The collected temperatures were paired and statistically analyzed by Wilcoxon signed rank test to assess the efficiency of cooling between methods. The room temperature and humidity in the treadmill room for the treadmill exercise was (mean ± SD) 27.2 ± 1.3°C and 49.9 ± 7.2% and in the corridor for cooling down was 30.0 ± 2.2°C and 49.0 ± 8.6%. Greater T CV and T R reductions were observed when cold water (W only & W scraping ) was applied compared with no water application (W no ) (T CV : −0.91°C for W only -W no , P < 0.001, −0.84°C for W scraping -W no , P < 0.001; T R : −0.31°C for W only -W no , P < 0.001, −0.29°C for W scraping -W no , P < 0.001), and overall the water application had more cooling down effect on T CV than T R (−0.57°C, P < 0.001). Between the 2 applied cold water methods, significantly lower body temperatures (T CV −0.11°C, P = 0.01; T R −0.03°C, P = 0.01) were observed with W only than W scraping . This study demonstrates that constant contact with water is more important for heat conduction and more effective than producing and using sweat evaporation to remove heat. Application of water without scraping may help decrease the core body temperature in horses more effectively in the early stage of EHI.

Exertional heat fatalities in Australian sport and recreation

ObjectivesTo describe the number and case characteristics of sport and recreation-related exertional heat deaths in Australia and summarise recommendations derived from case narratives. DesignDescriptive, population-based, retrospective cohort study. MethodsCases were identified using the National Coronial Information System (NCIS) through multiple search strategies comprising queries, keywords and cause of death codes. Cases were included where there was evidence that the deceased was actively engaged in sport or recreation and exertional heat illness was causal or contributory to the death. Data extraction were performed independently, in duplicate, to ensure accuracy. Descriptive statistics are used to report deceased's socio-demographic characteristics, incident characteristics, type of sport/recreational activity and time sequence of events. Content analysis is used to summarise recommendations. ResultsThirty-eight deaths (males n = 29, 74%; median age = 40 years, range 8–77) were identified during the study period (2001 to 2018), with 22 recommendations for five cases. Two cases occurred during organised sport and 36 during active recreation, of which 27 were in hiking. Eleven (29%) individuals were international visitors. There were 22 recommendations across 5 cases presented, with a focus on education and training. ConclusionsExertional heat deaths in outdoor recreation in Australia were far more prevalent than cases in organised sport. The largest proportion of deaths occurred in hiking with two populations featuring: males aged 15–45 years and international visitors. Considering the incident characteristics and time sequence of events, measures such as early recognition of symptoms, provision of first aid and timely access to emergency medical care are important to prevent fatalities.

Heat Stress Management in the Military: Wet-Bulb Globe Temperature Offsets for Modern Body Armor Systems.

The aim of this study was to model the effect of body armor coverage on body core temperature elevation and wet-bulb globe temperature (WBGT) offset. Heat stress is a critical factor influencing the health and safety of military populations. Work duration limits can be imposed to mitigate the risk of exertional heat illness and are derived based on the environmental conditions (WBGT). Traditionally a 3°C offset to WBGT is recommended when wearing body armor; however, modern body armor systems provide a range of coverage options, which may influence thermal strain imposed on the wearer. The biophysical properties of four military clothing ensembles of increasing ballistic protection coverage were measured on a heated sweating manikin in accordance with standard international criteria. Body core temperature elevation during light, moderate, and heavy work was modeled in environmental conditions from 16°C to 34°C WBGT using the heat strain decision aid. Increasing ballistic protection resulted in shorter work durations to reach a critical core temperature limit of 38.5°C. Environmental conditions, armor coverage, and work intensity had a significant influence on WBGT offset. Contrary to the traditional recommendation, the required WBGT offset was &gt;3°C in temperate conditions (&lt;27°C WBGT), particularly for moderate and heavy work. In contrast, a lower WBGT offset could be applied during light work and moderate work in low levels of coverage. Correct WBGT offsets are important for enabling adequate risk management strategies for mitigating risks of exertional heat illness.

Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies.

A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.