Effects of moisture absorption by clothing on thermal responses during intermittent exercise at 24°C

Abstract

The effects of two kinds of clothing with different properties with respect to moisture absorption on thermophysiological responses and pulse rate were studied during intermittent exercise at an ambient temperature (T _a) of 24°C. The two kinds of clothing ensemble tested were cotton T-shirt with short sleeves and cotton long-sleeved working dress with full-length trousers (C), and polyester T-shirt with short sleeves and polyester long-sleeved working dress with full-length trousers (P), the thermal resistances of which were nearly equal. Five women aged 21–32 years, served as subjects. The environmental conditions were 24°CT _a, 50% relative humidity and 0.14m·s⁻¹ air velocity. The subjects, wearing either C or P, exercised for 10-min on a cycle ergometer at an intensity of 30% maximal oxygen uptake and then 10-min rest. This sequence was repeated four times. Rectal and skin temperatures at several sites, local sweating rate, pulse rate and clothing microclimates were continuously compared between C and P throughout the experiment. The major findings were firstly, rectal temperature rose significantly higher in P; secondly, pulse rate was higher in P both during exercise and rest; thirdly, clothing surface temperature on the back rose highly significantly during the fourth exercise period and then fell significantly during the fourth rest period in C; and fourthly, four out of five subjects felt wetter in P during the latter half of the experiment. These results are discussed from the viewpoint that the reduced thermal insulation due to the absorption of moisture in C accelerated dry heat loss, resulting in an inhibition of the increases in core temperature and pulse rate.