The effect of two kinds of T-shirts on physiological and psychological thermal responses during exercise and recovery.

The aim of this study was to investigate the physiological and psychological responses during and after high-intensity exercise in a warm and humid environment in subjects wearing shirts of different fabrics. Eight healthy men exercised on two separate occasions, in random order, wearing two types of long-sleeve T-shirt: one made of polyester (PES) and the other of cotton fabric (CT). They performed three 20 min exercise bouts, with 5 min rest between each, and then rested in a chair for 60 min to recover. The ambient temperature was 25 °C and relative humidity was 60%. The exercise comprised of treadmill running at 8 km/h at 1° grade. Rectal temperature, skin temperatures at eight sites, heart rate, T-shirt mass and ratings of thermal, clothing wettedness, and shivering/sweating sensation were measured before the experiment, during the 5 min rest period after each exercise bout, and during recovery. Nude body mass was measured before the experiment and during recovery. The physiological stress index showed that the exercise produced a state of very high heat stress. Compared with exercise wearing the CT shirt, exercise wearing the PES fabric produced a greater sweating efficiency and less clothing regain (i.e., less sweat retention), but thermophysiological and subjective sensations during the intermittent high-intensity exercise were similar for both fabrics. However, skin temperature returned to the pre-exercise level faster, and the thermal and rating of shivering/sweating sensation were lower after exercise in the warm and humid environment in subjects wearing PES than when wearing the more traditional CT fabric.