Exercise and Heat Stress in Well-Healed Burn Survivors: Effects of Cooling Modalities on Thermal and Perceptual Responses.

Abstract

Burn injuries that require grafting impair thermoregulation, which may dissuade individuals with such injuries from being physically active. We tested the hypothesis that cooling modalities attenuate core temperature elevations and perceptions of heat stress during physical activity in the heat among adults with well-healed burn injuries. Adults with no burn injuries (non-burned), 20-40% body surface area burn injuries (moderate burn), and > 40% body surface area burn injuries (large burn) performed 1 hour of moderate intensity exercise (2.5 ± 0.2 mph and 2% grade) on four different occasions in two environmental conditions (30 °C & 39 °C, 40% relative humidity). Within each environmental condition, we applied one of the following cooling modalities, random assigned, for each visit: no cooling (control), fan at 4 m/s (fan), water spray every 5 min (water spray; scaled to burn area size), or a combination of water spray + fan. In 30 °C, perceptual strain index (PeSI) was reduced in the non-burned and moderate burn groups with water spray + fan, whereas PeSI was reduced with all cooling modalities in the large burn group. The cooling modalities did not affect core temperature responses. In the 39 °C environment, water spray and water spray + fan attenuated the elevation in core temperature (p ≤ 0.007) only in the large burn group. In the moderate burn group, PeSI was decreased with water spray + fan (p = 0.017). In the large burn group, both water spray alone and water spray + fan (p ≤ 0.041) lowered PeSI. For both environments across burn groups, the applied cooling modalities were generally more effective at reducing indices of perceptual strain relative to indices of thermal strain (e.g., core temperature).