Aerobic fitness and body fatness describe minimal variability in the thermoregulatory responses to exercise after accounting for heat production and body size

Matthew Cramer,Ollie Jay

doi:10.1186/2046-7648-4-s1-a11

Abstract

Aerobic fitness (VO2max) and body fatness have been regularly suggested as important determinants of core temperature and sweating responses to exercise [3,5], but recent studies suggest that biophysical factors related to heat production (Hprod), total body mass (TBM), and body surface area (BSA), predominantly influence rectal temperature changes (ΔTre) and sweating [1,2,4]. The present study tested the hypotheses that (i) individual variation in ΔTre, whole-body sweat loss (WBSL), and steady-state local sweat rate (LSRss) is determined primarily by Hprod (W.kg-1 TBM), evaporation required for heat balance (Ereq, W), and Ereq (W.m-2), respectively, and (ii) factors related to VO2max and body fat percentage (BF%) contribute minimally to the residual variance in these responses.

Highlights

Aerobic fitness (VO2max) and body fatness have been regularly suggested as important determinants of core temperature and sweating responses to exercise [3,5], but recent studies suggest that biophysical factors related to heat production (Hprod), total body mass (TBM), and body surface area (BSA), predominantly influence rectal temperature changes (ΔTre) and sweating [1,2,4]
Twenty-eight male subjects [TBM: 78.2(11.3) kg, BSA: 1.96(0.15) m2, VO2max: 3.86(0.68) L.min-1)] performed exercise at external workloads corresponding to a wide range of %VO2max (32.2-80.0%), Hprod (5.2-12.1 W.kg-1 TBM), and Ereq (256-672 W) in 24.8(0.7) °C, 33.4(12.2) % RH, and 1.2(0.1) m.s-1 air velocity
Tre and forearm LSR were measured continuously; whole-body sweat loss (WBSL) was estimated from changes in body mass

Summary

Introduction

Aerobic fitness (VO2max) and body fatness have been regularly suggested as important determinants of core temperature and sweating responses to exercise [3,5], but recent studies suggest that biophysical factors related to heat production (Hprod), total body mass (TBM), and body surface area (BSA), predominantly influence rectal temperature changes (ΔTre) and sweating [1,2,4]. The present study tested the hypotheses that (i) individual variation in ΔTre, whole-body sweat loss (WBSL), and steady-state local sweat rate (LSRss) is determined primarily by Hprod (W.kg-1 TBM), evaporation required for heat balance (Ereq, W), and Ereq (W.m2), respectively, and (ii) factors related to VO2max and body fat percentage (BF%) contribute minimally to the residual variance in these responses

Methods

Results

Conclusion