75 Burn Survivors Can Exercise for 30 Min, Even in the Heat, Without a Risk of Excessive Hyperthermia

Abstract

Abstract Introduction Excision of burned skin and subsequent grafting removes sweat glands and thereby impairs thermoregulation. Consequently, rehabilitation and associated exercise may be accompanied by a greater risk of hyperthermia, depending on exercise duration, intensity and environmental temperature. Current physical activity guidelines recommend adults perform at least 150 min of moderate-intensity exercise per week, which is often divided into 30-min daily sessions. This project tested the hypothesis that burn survivors could exercise for 30 min without excessive elevations in core body temperature, regardless of the total body surface area (%TBSA) burned or environmental temperature. Methods Ten subjects cycled for 60 min at 1) a moderate intensity (97±8 watts) in a thermoneutral environment (24°C, MOD_NEU), 2) a moderate intensity (100±17 watts) in a hot environment (39°C, MOD_HOT), and 3) a low intensity (65±10 watts) in a hot environment (39°C, LOW_HOT). Burn injuries were simulated by covering 0%, 20%, 40%, or 60% of the individual’s TBSA with an absorbent material that prevented sweat evaporation. Changes in gastrointestinal temperature (ΔTcore) were analyzed at 15-min increments throughout exercise. Results For the MOD_NEU trial, there were no differences in ΔTcore between the %TBSA coverage bouts at any time point during exercise. For the MOD_HOT trial, there were no differences in ΔTcore at 15 and 30 min of exercise regardless of the %TBSA coverage, while ΔTcore was appreciably elevated (P< 0.05) at 45 and 60 min of exercise for 20%+ TBSA bouts. For the MILD_HOT trial, there were no differences in ΔTcore at any time point between %TBSA bouts, with the sole exception of 60% simulated burn having a slightly greater ΔTcore (0.3±0.34°C; P< 0.05) at 60 min of exercise relative to the 0% TBSA bout. Conclusions These data indicate that individuals with up to 60% of their TBSA burned could exercise at a moderate intensity for 30 min, even in hot environmental conditions, without excessive elevations in body core temperature. Applicability of Research to Practice Individuals with significant burn injuries can benefit from exercise, without the risk of excessive hyperthermia, for up to 30 min in the heat or at least 60 min in an air conditioned space. Funding: DOD W81XWH-15-1-0647