EFFCTS OF VARYING SKIN TEMPERATURE DUE TO SEVERAL TYPES OF CLOTHIG ON TEMPERATURE RESPONSES AND HEAT-STRESS DURING EXERCISE / 体力科学

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 sport-swear, increases in esophageal (&Delta;Tes), mean skin (Tsk), mean body (Tb) temperature, heart rate (HR), thermal sensation (TS) at the end of exercise, and total sweat loss (<i>m</i>_sw, _tot) during exercise were significantly (p<0.01) higher in BB and FU than in NU. In comparison to WS or WV conditions, &Delta;Tes was significantly (p<0.01) higher under WV conditions than under NU, while there was no significant difference in &Delta;Tes between WS and NU. Tsk, Tb, HR, TS and <i>m</i>_sw, _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 &Delta;Tes markedly increased when Tsk exceeded 34°C ; and &Delta;Tes was significantly correlated with Tsk (r=0.861, p<0.01) for all conditions except WS14 and 20. For Tsk less than 34°C, however, &Delta;Tes remained constant. &Delta;Tes, Tsk, and Tb significantly correlated with HR (r=0.932, p<0.001), TS (r=0.888, p<0.001), and <i>m</i>_sw, _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.