The effect of water-perfused suits and vests on body cooling during exercise in a hot environment

In order to assess different methods of skin surface cooling to reduce exercise-heat stress, this study analyzed the differences in thermoregulatory responses between water-perfused suits (WS) and vests (WV) during exercise in a hot environment. Six male subjects performed three sessions of 20-min cycling at light intensity (250 W/m2) in a room maintained at 28°C (wet-bulb globe temperature, WBGT). The epperiment was performed under seven different conditions, involving three sets of clothing, WS or WV at 14°C (WS14, WV14), 20°C (WS20, WV20) and 26°C (WS26, WV26), and fencing uniforms (FU) only without cooling by water perfusion. In WS conditions, increases in Tes (ΔTes), mean skin temperature (Tsk), heart response (HR), thermal sensation (TS), and total sweat loss (TSL) were significantly (p<0.01) lower in WS14–26 than in FU, while there was no significant difference in the ΔTes between WS14, 20 and 26. In WV conditions, the ΔTes during exercise was similar between WV14, 20 and 26, and these values did not significantly differ from FU. The Tsk was significantly (p<0.01) lower in WV14 and 20 than in FU, and HR, TS and TSL tended to fall in WV14–26 according to the reduced water temperature perfused in the WV. These results show that during light exercise in a hot environment, (1) WS conditions can attenuate an increase in core temperature, and (2) WV conditions can reduce thermoregulatory responses associated with heat stress by lowering the perfused water temperature during exercise in a hot environment.