Biological sex does not independently influence time-dependent changes in core temperature and sweating of children exercising in uncompensable heat stress

Thomas H Topham, James W Smallcombe, Harry A Brown, Brad Clark, Andrew P Woodward, Richard D Telford, Ollie Jay, Julien D Périard

Research output: Contribution to journalArticlepeer-review

Abstract

PURPOSE: To investigate the influence of biological sex, independent of differences in aerobic fitness and body fatness, on the change in gastro-intestinal temperature (∆T gi) and whole-body sweat rate (WBSR) of children exercising under uncompensable heat stress.

METHODS: Seventeen boys (mean±SD; 13.7±1.3 years) and 18 girls (13.7±1.4) years) walked for 45 min at a fixed rate of metabolic heat production per kg body mass (8 W·kg -1) in 40°C and 30% relative humidity. Sex and V̇O 2peak were entered into a Bayesian hierarchical general additive model (HGAM) for T gi. Sex, V̇O 2peak and the evaporative requirement for heat balance (E req) were entered into a Bayesian hierarchical linear regression for WBSR. For 26 (12 M, 14 F) of the 35 children with measured body composition, body fat percentage was entered in a separate HGAM and hierarchical linear regression for T gi and WBSR respectively.

RESULTS: Conditional on sex-specific mean V̇O 2peak, ∆T gi was 1.00°C [90% credible intervals: 0.84, 1.16] for boys and 1.17°C [1.01, 1.33] for girls, with a difference of 0.17°C [-0.39, 0.06]. When sex differences in V̇O 2peak were accounted for, the difference in ∆T gi between boys and girls was 0.01°C [-0.25, 0.22]. The difference in WBSR between boys and girls was 0.03 L·h -1 [-0.02, 0.07], when isolated from differences in E req. The difference in ∆T gi between boys and girls was -0.10°C [-0.38, 0.17] when sex differences in body fat (%) were accounted for.

CONCLUSION: Biological sex did not independently influence the ∆T gi and WBSR of children exercising under uncompensable heat stress.

Original languageEnglish
Pages (from-to)1-31
Number of pages31
JournalJournal of applied physiology (Bethesda, Md. : 1985)
DOIs
Publication statusPublished - 25 Apr 2024

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