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

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 (ΔTes), 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, 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. 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 ΔTes markedly increased when Tsk exceeded 34°C ; and ΔTes 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, ΔTes remained constant. ΔTes, 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.

EFFECT OF SPORTS WEAR ON THERMOREGULATORY RESPONSE DURING EXERCISE IN A HOT ENVIRONMENT / 体力科学

To clarify the effect of sports wear on exercise-heat stress, we analyzed quantitative differences in thermoregulatory responses among baseball uniforms (BB), soccer uniforms (SC), and swimming trunks (NU) during exercise in a hot environment. Eight male subjects performed three sessions of 20-min cycling at light intensity (250W/m<SUP>2</SUP>) wearing BB, SC and NU in a room maintained at 28°C (wet-bulb globe temperatures, WBGT) . Esophageal (Tes), mean skin (Tsk), and mean body temperatures (Tb), heart rate (HR), thermal sensation (TS), and total sweat loss (<I>m</I><SUB>SW</SUB>) were measured during the exercise. Increases in Tes, Tsk, Tb, HR, and TS during exercise were significantly (p<0, 05) higher, and <I>m</I><SUB>SW</SUB>, was significantly (p<0.001) greater for BB than SC and NU. The increase in Tes at the end of the exercise was 3.0 times higher for BB than NU ; and also 2.0 times higher for SU than NU. Under all conditions, the increase in Tes significantly correlated with Tsk (r=0.634, p<0, 001) and HR (r=0.854, p<0.001) ; <I>m</I><SUB>SW</SUB> also significantly correlated with Tb (r=0.683, p<0.001) at the end of the exercise. These findings suggest that quantitative differences regarding the increase in Tes among BB, SC and NU relate to Tsk elevation due to attenuation of heat dissipation depending on sports wear ; body temperature elevation also relates to the increase in HR and <I>m</I><SUB>SW</SUB> during light exercise in a hot environment.