Relationships between subcutaneous fat and increase in body temperature during exercise in a warm environment

Abstract

The relationships between increase in rectal temperature and subcutaneous fat were studied during exercise in 10 male Japanese, aged 18 to 31 years old. The skinfold thicknesses were measured at six sites, i.e., triceps, chest, abdomen, iliac, subscapula, and thigh. Mean skinfold thickness (MSF), body density, body fat %, lean body mass (LBM), and body surface area(BSA) were calculated by the prediction equations. The subjects dressed only shorts and exercised on a bicycle ergometer for 32min at the two work loads, i, e., 300 and 600kgm/min, in a warm environment (DBT=28.5±1.71°C, WBT=23.9±1.62°C). Oxygen uptake (VO2) and increase in rectal temperature (ΔTr) were measured at the last of the exercise. Single correlation appeared to be significant between ΔTr and body weight (Wt), between ΔTr and LBM, and between ΔTr and BSA. The multiple regression equations of ΔTr (°C) on Wt (kg)and VO2 (ml/min), on LBM (kg) and VO2, and on BSA (m2) and VO2 were calculated respectively as, ΔTr=1.20-0.0282 Wt +0.000778 VO2, ΔTr=1.94-0.0469 LBM+0.000787 VO2, ΔTr=2.72-1.95 BSA+0.000780 VO2.These equations denote that the heavy body mass and the learge body surface area depress the increase in body temperature during exercise. The multiple correlation for *Tr, Wt, MSF, and VO2 was found to be highly significant (R=0.963, P<0.001), and the multiple regression equation of ΔTr(°C) on Wt (kg), MSF (mm), and VO2 (ml/min) was calculated as, ΔTr =2.11-0.0504 Wt+0.0416 MSF+0.000788 VO2.This may indicate that the subcutaneous fat prevents the heat loss from the body during exercise in a warm environment.