Abstract
Torii, M., and Hamada, S.Dept. Biol. & Func. & Eng., Graduate sch. Life Sci. & Systems Eng, Kyushu Instit. Tech., Kitakyushu JapanThermal balance and conductance in exercising pre-pubescent boysThe purpose of the present study was to compare thermal balance and conductance to cycle exercise of pre-pubescent boys (B) with those of adult men (AM). Subjects (5 elementary school boys, aged 11-12 yr and 5 university students, aged 19-22 yr) conducted cycle exercise for 40 min in an ambient temperature of 25°C (rh, 50%). Whole-body sweating, rectal (Tc) and skin temperatures (Tsk), oxygen uptake and heart rate were measured simultaneously. Thermoequilibrium and tissue conductance (K) were calculated. Metabolic rate increased in proportion with work intensity in both groups. Evaporative heat loss (E) and K during exercise at lower and moderate works were markedly lower in the B than in the AM. In contrast, heat storage of the body during exercise at the both lower and moderate works was significantly higher in the B than in the AM. Sensitivity of Tc-to-E relation was likely to same tendency in the AM and the B. In the B, threshold temperatures of Tc-to-E and Tc-to-K relation were significantly (P<0.01) sifted to hyperthermia side as compared with the AM. Tsk-to-K relation was positive correlations in the AM, but not significant relationship in the boys. The present results suggest that set-point temperature in the pre-pubescent children may be changed to hyperthermia. [Jpn J Physiol 54 Suppl:S229 (2004)]
