Prevalence of hypothermia and critical hand temperatures during military cold water immersion training

Cold-weather military operations can quickly undermine warfighter readiness and performance. Specifically, accidental cold-water immersion (CWI) contributes to rapid body heat loss and impaired motor function. This study evaluated the prevalence of hypothermia and critical hand temperatures during CWI. One-hundred seventeen (N = 117) military personnel (mean ± SD age: 27 ± 6 yr, height: 176 ± 8 cm, weight: 81.5 ± 11.6 kg) completed CWI and rewarming during cold-weather training, which included a 10-min outdoor CWI (1.3 ± 1.4°C) combined with cold air (−4.2 ± 8.5°C) exposure. Following CWI, students removed wet clothing, donned dry clothing, and entered sleeping systems. Core (T(c)) and hand (T(hand)) temperatures were recorded continuously during the training exercise. T(c) for 96 students (mean ± SD lowest T(c) = 35.6 ± 0.9°C) revealed that 24 students (25%) experienced T(c) below 35.0°C. All of 110 students (100%) experienced T(hand) below 15.0°C, with 71 students (65%) experiencing T(hand) at or below 8.0°C. Loss of hand function and hypothermia should be anticipated in warfighters who experience CWI in field settings. Given the high prevalence of low T(hand), focus should be directed on quickly rewarming hands to recover function.