Warfighter Physiological Status Monitoring (WPSM): Energy Balance and Thermal Status During a 10-Day Cold Weather U.S. Marine Corps Infantry Officer Course Field Exercise

摘要

Energy balance and thermal status was assessed in 14 male U.S. Marine Corps volunteers (age = 25 +/- 3 y MEAN +/- SD; ht = 178 +/- 5 Cm; wt = 81.0 +/- 4.1 kg; %body fat = 15 +/- 3; load = 42.6 +/- 3.2 kg) during a 10-day field exercise (FEX) at Quantico, VA. Question: Does intense physical activity, limited sleep, and restricted rations, combined with cold/damp weather, result in excessively negative energy balance and hypothermia. Methods: Total daily energy expenditure and water turnover were measured by doubly labeled water; daily food intake was assessed by ration wrapper collection; daily activity logs were maintained; weather data were collected with an automated weather station. Each volunteer wore wearable sensors that collected body core temperature, heart rate, activity patterns, and geolocation. Results: energy expenditure = 5378 +/- 678 kcal/d (22.51 +/- 2.84 MJ/d); energy intake 1333 +/- 196 kcal/d (5.58 +/- 0. 82 MJ/d); water turnover = 3.23 +/- 0.38 L/d. Carbohydrate intake was inadequate at 168 +/- 30 g/man/d. Rapid decreases in core temperature (approx. 0.8 0C/h) were sometimes evident during inactivity/sleep. Conclusions: (1) one MRE ration per day provided inadequate carbohydrate - an additional 225 g/d of carbohydrate was needed to meet the minimum 400 g/d requirement, and (2) additional sleeping gear is needed to avoid rapid decreases in core temperature and sleep disruption.