Abstract

The effectiveness of training in sweat clothing in cool conditions as a method of improving exercise-heat tolerance was assessed in 13 physically active subjects. After completing preliminary testing they were divided into a sweat clothing (SC) group (n = 7) and a normal clothing (NC) group (n = 6). Initially, no significant differences existed between the groups in sum of skinfolds, body surface area, body mass, maximal oxygen consumption (VO2max) or in rectal temperature (Tre), mean skin temperature (Tsk), heart rate (HR), blood lactate (HLa) or sweat rate (SR) response to a 60 min interval treadmill running test performed in a hot, humid environment (HTT1). The subjects then participated in 10 field training sessions over an 11 day period. During these sessions the SC group wore a suit of sweat clothing while the NC group trained in shorts, socks and T-shirts only. When re-tested for exercise-heat tolerance (HTT2) both groups had significantly lower Tre, Tsk, HR and HLa values than in HTT1. The only significant differences recorded between the groups were that the SC group had a smaller change in Tre (0-60 min) and a higher sweating sensitivity (SR per degree C rise in Tre) than the NC group. VO2max increased significantly over the training period in both the SC (6.4) and NC groups (4.9, NS between groups), and maximum HR declined by 4 bpm and 3 bpm respectively. Due to the increased endurance fitness evident in both groups and the improved responses of the NC group in HTT2 it was concluded that, at least in trained subjects, additional training in sweat clothing does not significantly add to the level of exercise-heat tolerance which can be gained from training in normal clothing. Whether the significantly lower change in Tre and greater sweating sensitivity evident in the SC group after training are sufficiently important to justify and endorse the use of sweat clothing is still open to question. Verf.-Referat