Ice Cooling Vest on Tolerance for Exercise under Uncompensable Heat Stress

This study was conducted to evaluate the effectiveness of a commercial, personal ice cooling vest on tolerance for exercise in hot (35 degrees C), wet (65% relative humidity) conditions with a nuclear biological chemical suit (NBC). On three separate occasions, 10 male volunteers walked on a treadmill at 3 miles per hour and 2% incline while (a) seminude (denoted CON), (b) dressed with a nuclear, biological, chemical (NBC) suit with an ice vest (V) worn under the suit (denoted NBCwV); or (c) dressed with an NBC suit but without an ice vest (V) (denoted NBCwoV). Participants exercised for 120 min or until volitional fatigue, or esophageal temperature reached 39.5 degrees C. Esophageal temperature (T-es), heart rate (HR), thermal sensation, and ratings of perceived exertion were measured. Exercise time was significantly greater in CON compared with both NBCwoV and NBCwV (p < 0.05), whereas T-es, thermal sensation, heart rate, and rate of perceived exertion were lower (p < 0.05). Wearing the ice vest increased exercise time (NBCwoV, 103.6 +/- 7.0 min; NBCwV, 115.9 +/- 4.1 min) and reduced the level of thermal strain, as evidenced by a lower T-es at end-exercise (NBCwoV, 39.03 +/- 0.13 degrees C; NBCwV, 38.74 +/- 0.13 degrees C) and reduced thermal sensation (NBCwoV, 6.4 +/- 0.4; NBCwV, 4.8 +/- 0.6). This was paralleled by a decrease in rate of perceived exertion (NBCwoV, 14.7 +/- 1.6; NBCwV, 12.4 +/- 1.6) (p < 0.05) and heat rate (NBCwoV, 169 +/- 6; NBCwV, 159 +/- 7) (p < 0.05). We show that a commercially available cooling vest can significantly reduce the level of thermal strain during work performed in hot environments.