Physiological Responses and Thermal,Humidity,and Comfort Sensations in Wear Trials with Cotton and Polypropylene Vests

Abstract

Relations were studied between skin temperature of the back as well as temperature and humidity inside clothing, and subjective estimates of thermal, humidity, and comfort sensations in 5 subjects wearing cross-country ski dress. The 2-h wear trials were performed in a climatic chamber at −2°C and simulated the actual circumstances under which such a dress is worn by alternating periods of intensive walking (20 min) on a treadmill with periods of resting (5–10 min). Each subject participated in 4 trials wearing alternately one of the 4 experimental, double-layer vests (double-cotton, cotton-polypropylene with cotton layer next to skin, same combination with polypropylene layer next to skin, double-polypropylene).

Skin temperature of the back was during the experiments systematically lower (P<0.05) by about 1°C with the double-layer cotton vest than with the double-layer polypropylene vest. Since the physical parameters of the two fabrics were not identical, the findings cannot be definitely attributed to the inherently different properties of the fibers. No significant differences were found in the 4 experimental series either in other objective measurements (temperature and humidity of the microclimate, energy output, total amount of sweat, amount of sweat trapped in the vests) or in subjective estimates of thermal, humidity, and comfort sensations.

Gradual increase of skin temperature as well as of temperature and humidity (sweating) of the microclimate was recorded during walking periods. When walking was interrupted by a pause, both the temperature and humidity rose steeply, due to the cessation of bellows ventilation of the clothing, and fell again when walking was resumed. The thermal and humidity sensations on the back reported after the turning-points of the intermittent activity showed opposite direction of changes than those of the recorded parameters—i.e., decrease during pauses and increase after walking was resumed. It is possible that the perception of local sensations was affected by superimposed, central perception of changes in the amount of heat delivered from muscles to the brain receptors. The sensations of comfort seemed to be affected mostly by perception of “warmth” when walking and “cold” when resting.