Effcts of varying skin temperature due to several types of clothig on temperature responses and heat-stress during exercise

Abstract

To clarify the effects of varying skin temperature due to several types of clothing on temperature responses and heat-stress during exercise, we analyzed thermoregulatory responses while wearing various types of sportswear including soccer (SC), baseball (BB), and fencing uniforms (FU), and while wearing water-perfused suits (WS) and vests (WV) during exercise in a hot environment. We also compared these results with those obtained under a semi-nude condition (NU). Eight male subjects performed three 20-min cycling sessions at light intensity (250W/m2) in a room maintained at 28°C (wet-bulb globe temperature, WBGT). The experiment was performed under ten conditions, with six sets of clothing, WS and WV at 14°C (WS14, WV14), 20°C (WS20, WV20) and 26°C (WS26, WV26), and FU, SC, BB or NU. While wearing sportswear, increases in esophageal (ΔTes), mean skin (T̄sk), mean body (T̄b) temperature, heart rate (HE), thermal sensation (TS) at the end of exercise, and total sweat loss (msw,tot) during exercise were significantly (p < 0.01) higher in BB and FU than in NU. In comparison to WS or WV conditions, ΔTes was significantly (p < 0.01) higher under WV conditions than under NU, while there was no significant difference in ΔTes between WS and NU. T̄sk, T̄b, HR, TS and mSw,tot tended to be lower in WS14 and 20, and higher in WV26 than in NU. Under all conditions at the end of exercise, the ΔTes markedly increased when Tsk exceeded 34°C ; and ΔTes was significantly correlated with T̄sk (r=0.861, p < 0.01) for all conditions except WS14 and 20. For T̄sk less than 34°C, however, ΔTes remained constant. ΔTes, T̄sk, and T̄b significantly correlated with HR (r=0.932, p < 0.001), TS(r=0.888, p < 0.001), and msw,tot (r=0.961, p < 0.001), respectively. These results show that during light exercise under hot conditions, 1) in several types of clothing, a critical level of skin temperature causing core temperature elevation may exist, 2) cooling the skin temperature can alleviate heat-stress due to body temperature elevation, and 3) the semi-nude condition is the simplest method of alleviating core temperature elevation without using body cooling materials such as WS or WV.