Describing individual variation in local sweating during exercise in a temperate environment

It has been previously demonstrated that the individual variation in whole-body sweat rate is described by differences in each participant’s heat balance status. It was hypothesized that the individual variation in local sweat rate of the forehead (LSRhead) and forearm (LSRarm) would be similarly described using a whole-body heat balance approach, specifically the ratio of evaporation required for heat balance relative to the maximum evaporation possible (i.e. Ereq:Emax). Twelve males cycled at 60% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \dot{V}{\text{O}}_{{ 2 {\text{max}}}} $$\end{document} for 60 min at 24.9 ± 0.5°C, 31 ± 14% relative humidity. Rectal (Tre) and aural canal (Tau) temperatures as well as mean skin temperature (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \bar{T}_{\text{sk}} $$\end{document}), metabolic energy expenditure (M) and rate of external work (W) were measured throughout. In addition, whole-body sweat rate at steady state (WBSRss) was estimated using the change in body mass over the last 15 min of exercise, with LSRhead and LSRarm estimated using technical absorbent patches applied between the 50th and 55th minute. WBSRss significantly correlated with M–W (r = 0.66, P = 0.021), Ereq (r = 0.69, P = 0.013) and Ereq:Emax (r = 0.87, P < 0.001); LSRhead was significantly correlated with Ereq:Emax (r = 0.82, P = 0.001), but not M–W (r = 0.31, P = 0.328) or Ereq (r = 0.38, P = 0.227); and LSRarm significantly correlated with Ereq (r = 0.62, P = 0.031) and Ereq:Emax (r = 0.78, P = 0.003) but not M–W (r = 0.56, P = 0.059). None of WBSRss, LSRhead or LSRarm significantly correlated with any variations in Tre, Tau or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \bar{T}_{\text{b}} $$\end{document} (i.e. 0.8Tre + 0.2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \bar{T}_{\text{sk}} $$\end{document}). Secondary analyses also demonstrated that both LSRhead (r = 0.79, P = 0.002) and LSRarm (r = 0.89, P < 0.001) correlated with WBSRss. In conclusion, the individual variation in WBSRss, LSRhead and LSRarm is described by the ratio of Ereq relative to Emax.