Exertional heat stroke in sport and the military: epidemiology and mitigation

Abstract

New findings: What is the topic of this review? Exertional heat stroke epidemiology in sport and military settings, along with common risk factors and strategies and policies designed to mitigate its occurrence. What advances does it highlight? Individual susceptibility to exertional heat stroke risk is dependent on the interaction of intrinsic and extrinsic factors. Heat policies in sport should assess environmental conditions, as well as the characteristics of the athlete, clothing/equipment worn and activity level of the sport. Exertional heat stroke risk reduction in the military should account for factors specific to training and personnel.

Abstract: Exertional heat illness occurs along a continuum, developing from the relatively mild condition of muscle cramps, to heat exhaustion, and in some cases to the life-threatening condition of heat stroke. The development of exertional heat stroke (EHS) is associated with an increase in core temperature stemming from inadequate heat dissipation to offset the rate of metabolically generated heat. Susceptibility to EHS is linked to the interaction of several factors including environmental conditions, individual characteristics, health conditions, medication and drug use, behavioural responses, and sport/organisational requirements. Two settings in which EHS is commonly observed are competitive sport and the military. In sport, the exact prevalence of EHS is unclear due to inconsistent exertional heat illness terminology, diagnostic criteria and data reporting. In contrast, exertional heat illness surveillance in the military is facilitated by standardised case definitions, a requirement to report all heat illness cases and a centralised medical record repository. To mitigate EHS risk, several strategies can be implemented by athletes and military personnel, including heat acclimation, ensuring adequate hydration, cold-water immersion and mandated work-to-rest ratios. Organisations may also consider developing sport or military task-specific heat stress policies that account for the evaporative heat loss requirement of participants, relative to the evaporative capacity of the environment. This review examines the epidemiology of EHS along with the strategies and policies designed to reduce its occurrence in sport and military settings. We highlight the nuances of identifying individuals at risk of EHS and summarise the benefits and shortcomings of various mitigation strategies.

Keywords: exercise; heat illness; hyperthermia.

FIGURE 1

Factors associated with an increased risk of exertional heat stroke. Individual susceptibility to exertional heat stroke is dependent on the interaction of both intrinsic and extrinsic factors.

FIGURE 2

Strategies and policies designed to mitigate the risk of exertional heat stroke. Individual athletes and military personnel can attenuate the risk of experiencing exertional heat stroke by ensuring that they are adequately fit, acclimated/acclimatised to the environmental conditions and properly hydrated prior to and during vigorous exercise in the heat. Cooling strategies (external and internal) employed prior to and during exercise, along with good quality sleep, may also mitigate the risk of exertional heat stroke. Finally, empirically based sport and military‐specific heat policies are critical in safeguarding the health of athletes and military personnel.