Strategies for increasing evaporative cooling during simulated desert patrol mission

The study evaluated the efficiency of two heat dissipation strategies under simulated desert patrol missions. Ten men participated in four trials, during which they walked on a treadmill (45 degrees C, 20% relative humidity), carrying a load of 35kg; two 50-min walks were separated by a 20-min rest. Cooling strategies, provided by an ambient air-ventilated vest (active cooling condition, AC), or water spraying of the skin during the rest (passive cooling condition, PC), in addition to reduced clothing and open zippers, were compared to conditions with full protective (FP) clothing and naked condition (NC). Skin temperature was higher during NC (37.90.4 degrees C; p<0.001), and rectal temperature and heart rate were higher during FP (38.6 +/- 0.4 degrees C, p<0.001 and 145 +/- 12, p<0.001, respectively), compared to other conditions. Four subjects terminated the trial prematurely due to signs of heat exhaustion in FP. Both cooling strategies substantially improved evaporative cooling.