Effects of simulated weightlessness on thermal sweating of human body: An experimental study

Abstract

Thermal sweating is the thermoregulatory activity of the human body in hot and warm environments, which is critical to the human thermal comfort and health. The sweating of a human body in a real weightlessness environment has seldom been researched, and simulated weightlessness has usually been conducted under comfortable environments. In order to study the sweating of the human body under weightlessness, a 7-day −6° head down bed rest experiment was carried out on six male subjects lying on their backs to simulate the physiological changes that occur under a weightless environment. The skin microcurrents of the subjects were recorded to evaluate sweating under a range of environments. The results showed that sweating was more significant in the torso and head areas than on the arms and lower body. The whole body sweat rates of subjects were lower than those before the simulated weightlessness experiment. However, the threshold air temperature for the onset of sweating under simulated weightlessness was higher than that before the simulation. This was possibly due to the raising of thermoregulatory set-point temperature of the body. Findings have shown that the sweating behaviour and thermal response of a male human body in a weightless environment could be different to those in the terrestrial condition.

Thermal comfort under weightlessness: A physiological prediction

“…We postulate that the 'set-point' of the thermoregulation could be raised under the simulated weightlessness, so the onset core body temperature would also be raised for the onset of sweating. 26 Besides, the overall lower sweat rate of participants after HDBR has been observed. The differences observed could be induced by the loss of body fluid of participants during HDBR experiment.…”

“…The measurement locations were in the forehead, thorax, back, left forearm, left thigh and left calf. 26 These locations were marked to ensure that the same electrodes of the device were attached at the same locations for measurements. The skin current was measured five times at each location.…”

“…Air temperatures were set at 32°C and 35°C to provide an adequate stimulus for the physiological sweating of all participants. The relative humidity (RH) selected during Stage 1 and Stage 3 was the same as our previous studies 26,29 (30 ± 3%, 45 ± 3%, 60 ± 3%, 80 ± 3%). As for the air movement, our previous findings revealed that it has much less effect on the thermal comfort than the air temperature under simulated weightlessness; thus, the air movement was not included in our research.…”

“…An environmental chamber, which has been described previously, 34 was used to realise different temperatures for the experiment. In this study, participants were exposed to seven different temperatures ( 26,29 (30 AE 3%, 45 AE 3%, 60 AE 3%, 80 AE 3%). As for the air movement, our previous findings revealed that it has much less effect on the thermal comfort than the air temperature under simulated weightlessness; thus, the air movement was not included in our research.…”

Performance evaluation of different air distraction system on thermal uniformity and energy saving: A case study of a Japanese detached house

“…4,5 There have been many studies on the potential of CFD to assist thermal environment analysis and human comfort assessments. 6–8 Comfortable healthy indoor environment has become a major concern since people pay more attention to meet requirements of acceptable indoor thermal uniformity, and directly affect occupants’ cognitive alliesthesia. 9,10 Against this back ground, a new concept of involving duct system with the room air conditioner to minimize the air temperature irregularity or uneven distribution among all target spaces has been introduced in this paper.…”