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KMID : 0352819880040010037
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Kosin Medical Journal
1988 Volume.4 No. 1 p.37 ~ p.43
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CHANGES IN THERMAL INSULATION DURING UNDERWATER EXERCISE
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Park Yang-Saeng
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Abstract
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I. Steady-state thermal insulation was measured in protected and unprotected subjects during rest. and exercise in water of critical temperature.
2 . In unp -otected subjects, maximal body insulation at rest increased as a linear function of mean subcutaneous fat thickness. In all subjects, however, body insulation declined as an exponential. function of the exercise intensity, reaching approximately 25% of the resting value at work loads above 4 Met. These suggest that over 75% of maximal body insulation in resting subjects is achieved by use of skeletal muscle as an insulatioe barrier.
3. In wet-suited subjects, the overall insulation decreased to 1/2 with 2 Met and to 1/3 of the resting value with 3 Met exercise. This decrease in total insulation was due in part to the reduction in body insulation and in part to the decrease in insulation afforded by wet-suits. The reduction in apparent suit insulation during exercise may be attributed primarily to an increase in the effective heat exchange surface area as a result of exercise hyperemia of the limbs which are poorly insulated as compared with the trunk.
4. As a practical consequence, both in protected and unprotected individual, heat generated by muscular exercise in water colder than critical temperature cannot offset cooling unless the exercise intensity is great.
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