Exertional heat illness (EHI) in athletes

This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of exertional heat illness occurring in athletes

Heat Stroke in Physical Activity and Sport

Exertional heat stroke (EHS) is one of the leading causes of sudden death in sport and physical activity. In American Football alone, there have been 46-documented EHS fatalities in the United States between 1995 and 2010. In 2003, National Collegiate Athletics Association mandated pre-season heat acclimatization guidelines, which successfully decreased the number of heat stroke fatalities in collegiate American football. However, despite the advancement in modern medical care and increased awareness in heat safety, lack of appropriate on-site medical care is still contributing to EHS seen especially at the youth level. It is well established in scientific literature that fatalities as a result of EHS are largely preventable with proper education on the knowledge of recognition, treatment, and prevention of EHS. This document provides a review of the current best medical practices and evidence on the epidemiology, pathophysiology, risk factors, recognition, treatment, prevention, and return to play recommendations for EHS, specifically as they relate to sport and physical activity

Incidence and predictors of exertional hyperthermia after a 15-km road race in cool environmental conditions

Objectives Current knowledge about the incidence and risk factors for exertional hyperthermia (core body temperature ≥40 °C) is predominantly based on military populations or small-sized studies in athletes. We assessed the incidence of exertional hyperthermia in 227 participants of a 15-km running race, and identified predictors for exertional hyperthermia. Design Observational study. Methods We measured intestinal core body temperature before and immediately after the race. To identify predictive factors of maximum core body temperature, we entered sex, age, BMI, post-finish dehydration, number of training weeks, fluid intake before and during the race, finish time, and core body temperature change during warming-up into a backward linear regression analysis. Additionally, two subgroups of hyperthermic and non-hyperthermic participants were compared. Results In a WBGT of 11 °C, core body temperature increased from 37.6 ± 0.4 °C at baseline to 37.8 ± 0.4 °C after warming-up, and 39.2 ± 0.7 °C at the finish. A total of 15% of all participants had exertional hyperthermia at the finish. Age, BMI, fluid intake before the race and the core body temperature change during warming-up significantly predicted maximal core body temperature (p < 0.001). Participants with hyperthermia at the finish line had a significantly greater core body temperature rise (p < 0.01) during the warming-up compared to non-hyperthermic peers, but similar race times (p = 0.46). Conclusions 15% of the recreational runners developed exertional hyperthermia, whilst core body temperature change during the warming-up was identified as strongest predictor for core body temperature at the finish. This study emphasizes that exertional hyperthermia is a common phenomenon in recreational athletes, and can be partially predicted

Susceptibility to exertional heat illness and hospitalisation risk in UK military personnel.

BACKGROUND: Susceptibility to exertional heat illness (EHI) is considered multifactorial in nature. The aims of this study were to (1) review traditional susceptibility factors identified in cases of EHI and (2) determine how they are related to risk of hospitalisation. METHODS: Review of an electronic database of EHI reported in the British Army between 1 September 2007 and 31 December 2014. Cases were categorised by demographic, situational and susceptibility variables. Univariate and multivariate logistic regression was performed for the OR for hospitalisation by risk factor. RESULTS: 361 reports were included in the analysis. 33.5% of cases occurred in hot climates, 34.6% in temperate climates during summer months and 31.9% in temperate climates outside of summer months. Traditional susceptibility factors were reported in 193 but entirely absent from 168 cases. 137 cases (38.0%) were admitted to hospital. Adjusted OR for hospitalisation was lower for recruits (OR 0.42, 95% CI 0.18 to 0.99, p<0.05) and for personnel wearing occlusive dress (OR 0.56, 95% CI 0.34 to 0.93, p<0.05) or unacclimatised to heat (OR 0.31, 95% CI 0.15 to 0.66, p<0.01). CONCLUSIONS: The global, year-round threat of EHI is highlighted. Absence of susceptibility factors in nearly half of reports highlights the challenge of identifying EHI-prone individuals. Paradoxical association of traditional susceptibility factors with reduced hospitalisation risk may reflect the contemporary contexts in which severe EHI occurs. These findings also suggest a need for better evidence to inform guidelines that aim to prevent severe EHI concurrent to reducing overall morbidity

National Collegiate Athletic Association Strength And Conditioning Coaches\u27 Knowledge And Practices Regarding Prevention And Recognition Of Exertional Heat Stroke

The purpose of this study was to assess and determine the current level of knowledge that National Collegiate Athletic Association (NCAA) Strength and Conditioning Coaches (SCCs) possess regarding exertional heat stroke (EHS) prevention and recognition and to determine if SCC certification type had any effect. Major findings of this study support the view that SCCs need more preparation, education and training to increase their competency in preventing and recognizing EHS. Research found that there was no significant difference in scores on the EHS scale based on SCC certification (CSCS vs. SCCC) after accounting for experience, education or division but the CSCS certified professionals scored higher on all the factors as compared to SCCs without the CSCS.. The major key finding was that SCCs lacked essential knowledge to prevent or recognize EHS. Furthermore, the study defines relevant EHS prevention and recognition competencies that an undergraduate curriculum, graduate curriculum and professional certification providers, should include and emphasize in their preparation programs

Consensus recommendations on training and competing 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 optimize performance during sporting activities undertaken 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 an euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vests), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers 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 competitions are held in the heat

Occupational cooling practices of emergency first responders in the United States: A survey

This is an accepted manuscript of an article published by Taylor & Francis in Temperature on 29/07/2018, available online: https://doi.org/10.1080/23328940.2018.1493907 The accepted version of the publication may differ from the final published version.© 2018 Informa UK Limited, trading as Taylor & Francis Group. Despite extensive documentation directed specifically toward mitigating thermal strain of first responders, we wished to ascertain the degree to which first responders applied cooling strategies, and what opinions are held by the various agencies/departments within the United States. An internet-based survey of first responders was distributed to the International Association of Fire Chiefs, International Association of Fire Firefighters, National Bomb Squad Advisory Board and the USA Interagency Board and their subsequent departments and branches. Individual first responder departments were questioned regarding the use of pre-, concurrent, post-cooling, types of methods employed, and/or reasons why they had not incorporated various methods in first responder deployment. Completed surveys were collected from 119 unique de-identified departments, including those working in law enforcement (29%), as firefighters (29%), EOD (28%) and HAZMAT technicians (15%). One-hundred and eighteen departments (99%) reported heat strain/illness to be a risk to employee safety during occupational duties. The percentage of departments with at least one case of heat illness in the previous year were as follows: fire (39%) HAZMAT (23%), EOD (20%) and law enforcement (18%). Post-cooling was the scheduled cooling method implemented the most (63%). Fire departments were significantly more likely to use post-cooling, as well as combine two types of scheduled cooling compared to other departments. Importantly, 25% of all departments surveyed provided no cooling whatsoever. The greatest barriers to personnel cooling were as follows–availability, cost, logistics, and knowledge. Our findings could aid in a better understanding of current practices and perceptions of heat illness and injury prevention in United States first responders. Abbreviations: EOD: explosive ordnance disposal; HAZMAT: hazardous materials.This project is financially supported by the United States Government through the United States Department of Defense (DOD).Published versio

Thermoregulation in exercising horses: Aspects of temperature monitoring during field exercise

Joint Degree Program between the School of Animal and Veterinary Science, University of Adelaide, and Faculty of Veterinary Medicine, Ghent University, BelgiumHyperthermia is an ongoing welfare and performance issue for all horses exercising in racing and other competitive sport events. At present, little is known about the influence of core body temperature evolvement on hyperthermia in real time during different types of exercise performed in field conditions such as racing and endurance events. Consequently, it is becoming increasingly important to establish appropriate policies regarding the detection and prevention of all types of heat stress. To achieve this, a detailed view of the variability of equine thermoregulation during field exercise and recovery is essential. To date, the vast majority of thermoregulatory studies have been conducted in indoor laboratory conditions using a treadmill and subjecting horses to specific standardized exercise tests. However, this approach cannot successfully reflect real-time field conditions. Hence, there is a need to accurately and reliably monitor equine core body temperature responses to avoid potential harm due to increasing heat load. Chapter 1 provides a review of current research into thermoregulation, hyperthermia and exertional heat illness (EHI) in exercising horses. In addition, several temperature monitoring methods in horses are described along with some relevant methods in human athletes. However, no studies have investigated the promising continuous monitoring method involving a telemetric gastrointestinal pill (GI) that can be applied in the field in all conditions. Chapter 2 outlines the scientific aims of the thesis. Chapter 3 describes a study designed to evaluate the efficacy of continuous monitoring of core body temperature using the novel telemetric GI pill during real-time field exercise for the first time. The results showed that the continuous recording of the GI core temperature in exercising horses in the field using the GI pill was non-invasive, practical and accurate. Temperature fluctuations experienced during exercise and recovery are reliably recorded, and tendencies toward EHI will be easily observed during field exercise. Importantly, the GI pill has proven to be a more accurate and precise tool to monitor core thermal response when compared with serial Tre measurements in the field. Summary 194 Chapter 4 describes the application of this novel thermoregulation monitoring method in detail. The study involved measurements conducted in both endurance horses and trotters in order to compare exercise types in real-life competitions in the field. Not only were the core body temperatures (Tc) continuously monitored during exercise and recovery, the thermoregulatory responses to the different exercise intensities were also compared. The findings of this study reported real-time temperature evolvement during real-time competition in the field. More specifically, endurance horses reached peak temperature at 75% of completion of 40 km of exercise. However, trotters reached peak temperature always during recovery. In addition, the Tc in endurance horses returned to baseline within 60 minutes into recovery while in 30% of trotters, Tc was still higher than 39°C at the end of recovery. Since endurance horses are considered as ‘fit to continue’ competition when the heartrate (HR) is 60 beats per minute or below, the finding that the mean Tc was still 38.8 ± 0.4°C at a HR of 60 bpm is of importance. Overall, the study showed that horses have very individual thermoregulatory responses which require highly accurate monitoring no matter what type of exercise is performed in the field. Chapter 5 investigated the usefulness of monitoring skin temperature in endurance horses. A large array of skin temperature methodologies recently used in the field is reviewed, mainly pre- and post-exercise at time points, In this study, to evaluate if skin temperature could be used as a proxy for core temperature, the skin temperature was continuously monitored and evaluated using an infrared monitor during a real-life endurance competition. The skin temperature was compared to the GI temperature and importantly, there was no correlation between skin and GI temperature.Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 202