Thermophysiological Responses to the Alternation of Exercise and Rest at when Wearing Underwear made of Cotton or Wool

The purpose of this study was to investigate the effects of two kinds of underwear material on subjects exercising and resting in an ambient temperature of $20^{\circ}C$, a relative humidity of 60% and an air velocity of 0.13m $see^{-1}$. Two kinds of underwear ensemble were tested, differing in their hygroscopic properties: 100% wool (W) with higher moisture regain and 100% cotton (C) with lower moisture regain. Five young females served as subjects. The experiments comprised two repeated periods of 15 min exercise on a treadmill with a speed of 6km $h^{-1}$ followed by 10 min rest. The main results were as follows: 1) Mean skin temperature was significantly higher in W than in C throughout the whole experimental period (p<0.05). 2) The temperature and humidity of the microclimate between the skin and underwear provided by the first layer of clothing was higher in W than in C (p<0.1 and p<0.05, for temperature and humidity, respectively). 3) Heart rate was significantly higher in W than in C (p<0.05). 4) Subjects felt warmer during the second exercise session when wearing wool rather than cotton (p<0.05), and they also reported more increased wetness during the second exercise and rest periods in W than in C (p<0.05). These results suggest that underwear made of wool with higher moisture regain might not act as effectively as cotton to transfer exercise-induced heat from the body to the surrounding air when light exercise is taken in a thermally-neutral environment.