Heat Acclimatization Through Progressive Overdressing in Fire Academy Students

Objective: To assess the effectiveness of a field-expedient, pre-fire-season heat acclimatization protocol to reduce heat strain in fire academy students. Methods: Seventeen fire academy students completed 10 days of outdoor, firefighter-relevant functional exercise. Daily peak rectal temperature guided the progressive addition of turnout gear (i.e., pants, helmet, jacket, SCBA) to achieve an isothermal heat stimulus. Day 1 and Day 10 outcomes were compared. Results: Active exercise time (63.1±18.3 vs 73.0±7.8 min; p =.014), 20-minute run distance (1.66±0.33 vs 2.16±0.57 km; p =.002), and sweat rate (0.83±0.32 vs 1.26±0.80 L/h; p =.012) increased while resting rectal temperature (37.49±0.35 vs 37.24±0.19°C; p =.015) and heart rate (95±13 vs 85±11 bpm; p =.012) decreased from before to after heat acclimatization, respectively. Conclusions: Progressive overdressing during firefighter-relevant functional exercise appears to be a feasible, accessible heat acclimatization strategy that improves thermoregulation and exercise-heat capacity.