Anthropometric and Demographic Differences in Human Thermophysiology under Light Activity

Abstract

This paper presents findings on variations in human thermoregulatory response due to demography and anthropometry by studying different subjects during periods of rest, moderate walking and recovery. Sixteen subjects participated in the present study. Controlled experiments were conducted under similar environmental conditions (ambient air temperature and relative humidity). Subjects underwent four phases of experiments : (i) steady- state measurements, (ii) 15-min walk, (iii) 15-min recovery in a sitting position, and (iv) post experiment measurements. There were significant differences in mean skin temperature (T_sk,mean) at rest between genders. However, no significant differences were observed in T_sk,mean between age groups. Core temperatures (T_c) at rest were not significantly different between gender and age groups. Body Mass Index (BMI) and weight were observed to be positively correlated to T_sk,mean of subjects at rest. It was observed that subjects with lower BMI tended to have lower local skin temperatures (T_sk) in their extremities. On the other hand, subjects with higher BMI tended to have slightly lower T_sk in their trunks but higher T_sk in the extremities of their bodies. Elderly male subjects had significantly higher T_sk,mean than other demographic groups in the experiments. Anthropometry of subjects did not influence the change in T_c during moderate walking and recovery period. Although T_sk,mean was observed to generally decrease with BMI during moderate walking, no significant correlation was observed. However, T_sk,mean gain was observed to be marginally dependent on weight and body surface area (BSA) during the recovery period. During the moderate walking phase, subjects with BMI above 23 were observed to have reduced T_sk in a few parts of their body. Conversely, subjects with BMI under 21 experienced increase T_sk across most body parts, especially their extremities. Overall, during moderate walking, sweat rate (SR) was significantly correlated to both BSA and BMI. At similar BMI levels, the SR of males were observed to be greater than that of females. The results show that gender and anthropometric conditions have a significant effect on the thermoregulatory response of subjects at steady-state and during moderate walking. Variation in the T_sk across different demographic and anthropometric groups suggest that these differences have to be considered when considering localized comfort of subjects.