Specific Exercise Heat Stress Protocol for a Triathlete’s Return from Exertional Heat Stroke

Abstract

A triathlete collapsed with exertional heatstroke (EHS) during 2 races over 3 months. The American College of Sports Medicine recommends a heat tolerance test (HTT) following EHS if there is a concern with return to play. The classical walking HTT may not be the best test to evaluate elite triathletes' heat tolerance due to race intensity, nor is it suited to evaluate acclimation ability, which may play a role in risk of heat illness. Is the athlete capable of returning to racing or should he retire from sport due to heat intolerance? Up to 90 min of cycling (70% of V˙O2max; 36°C, 50% relative humidity) was followed by 9 d of exercise heat acclimation and a final identical exercise heat stress test. After acclimation, exercise duration before reaching a gastrointestinal temperature (Tgi) of 39.5°C increased 25 min, sweat rate increased 0.5 L·h, initial Tgi decreased 0.85°C, and rate of Tgi rise decreased 0.6°C·h. Adaptations were deemed acceptable, and the athlete was allowed to return to competition. The athlete has since raced in hot environments without incident.

Repeatability of a running heat tolerance test

“…Furthermore, Nielsen (1996) provides data to suggest the incidence of heat illness is unavoidable for endurance runners when competing in a high ambient temperature combined with high relative humidity without a severe reduction in endurance performance; highlighting the importance of thorough preparation to prevent the incidence of a heat illness. The findings in the current study could be applied in a manner that would serve to minimise the number of athletes that suffer from hyperthermia, by supporting a more complete evaluation and subsequent preparation prior to training and competing in the heat (Johnson et al, 2013).…”

“…Experimental procedures have been applied to cause a rise in core temperature under resting and exercise conditions to challenge the thermoregulatory responses (Inoue et al, 2005;Johnson et al, 2013;Kenney and Hodgson, 1987;Montain et al, 1994). These procedures are used as a method of assessing the ability of an individual to withstand heat stress and evaluate heat dissipating mechanisms.…”

Thermal stress, human performance, and physical employment standards

“…Yet, the United States military does not adopt the HTT for this purpose (Kazman et al 2013;Lisman et al 2014). The validity of the HTT has also been questioned (Johnson et al 2013;O'Connor et al 2010). For example, it is unclear whether the HTT can predict the occurrence of future heat-related illnesses (O'Connor et al 2010).…”

Heat-related illness in sports and exercise

“…The Israeli Defense Forces use a standard heat tolerance test (HTT) to assess readiness for return to military activities [53][54][55]56•], although experts question the validity and applicability of this test to determine safe sports clearance for athletes [40••]. A new HTT protocol was designed and utilized for an elite triathlete with prior episodes of EHS [57].…”