Changes in temperature and humidity at different layers inside clothing during rest, exercise, and recovery.

This paper presents the results of experiments in which we measured humidity and temperature changes that took place in different layers inside and on clothing. The experiments were conducted during rest, exercise, and recovery. During each experiment, subjects wore one of three kinds of outerwear made of three different materials, respectively. These materials were nylon taffeta (N), nylon taffeta-Goretex-nylon tricot laminated fabric (G), and polyvinylchloride-coated plain cotton fabric (V). The subjects wore an undershirt and a T-shirt under the outerwear.<BR>The humidity and the temperature were measured in the following parts of each subjects' back: (1) the layer between the subject's skin and the undershirt (first layer), (2) the layer between the undershirt and the T-shirt (second layer), (3) the layer between the T-shirt and the outerwear (third layer), and (4) the surface of the outerwear (fourth layer).<BR>We also measured the sensation of comfort, the skin temperature, the oral temperature and the degree of sweating of the subjects.<BR>The experiments were conducted in a climatic chamber under conditions of 20.7±0.4°C, 61.2±3.6% RH and 2.5±0.5cm/sec.<BR>The results we obtained were as follows:<BR>1) While the subjects kept still, little change of humidity was observed with time in all the four layers. When the subjects were in motion, humidity increased as they started sweating. After the exercise ended, the humidity reached its maximum and then gradually decreased.<BR>2) When subjects kept still, there was no difference in humidity in all the four layers of the outerwear. After the subjects began sweating with exercise, humidity rose in the first layer, followed in order by the second, the third, and the fourth layers. The humidity difference between the third layer (inside the clothing) and the fourth layer (the surface of the clothing) was greatest with outerwear V and was least with outerwear N.<BR>3) During rest, exercise, and recovery, the humidity interrelationships of the first, the second, and the third layer were: outerwear V>outerwear G>outerwear N. The humidity interrelationship of the fourth layer was: outerwear N>outerwear G>outerwear V.<BR>4) Before exercise, there were no changes in the temperatures of any of the four layers, regardless of the type of outerwear. After exercise took place, in the first and the second layers, the temperature remained unchanged for the first 7 to 8 minutes and then gradually went up. In the third and the fourth layers, the temperature went down once and then gradually went up. After subjects stopped moving, the temperatures of the four layers reached their peaks and then showed a gradual decrease.<BR>5) During rest, exercise, and recovery, the skin temperature and the first layer temperature were the same. Temperature decreases were first observed in the first layer, then followed by the second, the third, and the fourth layers.<BR>6) Before the motion started, there was no difference in the temperature of each layer of the three pieces of outerwear. The individual layer temperature of outerwear V was the highest at the maximum temperature point and at the temperature point 45 minutes after the motion stopped. The temperatures of outerwear N and outerwear G showed no significant differences.<BR>7) The changes in the comfort sensation, the thermal sensation and the humidity sensation almost agreed with the temperature and the humidity changes inside clothing.<BR>8) The permeability of outerwear materials turned out to have a considerable influence on the degree of sweating, the temperature and the humidity conditions inside clothing.