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Whole‐body sweat production during exercise: Evaporative heat loss requirement or percent VO 2max ?
Author(s) -
Kenny Glen P,
Gag Daniel,
Jay Ollie
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1201.23
Subject(s) - sweat , vo2 max , chemistry , zoology , calorimetry , medicine , endocrinology , heart rate , biology , thermodynamics , physics , blood pressure
Under conditions which permit full evaporation of the sweat produced, the evaporative heat loss requirement ( E req ) should determine whole‐body sweat production during exercise. Yet, most exercise temperature regulation studies employ a fixed percentage of maximum oxygen consumption (VO 2max ) when examining sweat production between independent groups. We therefore examined the relationship between sweat production and E req , as well as %VO 2max during exercise. Twenty‐three males either performed exercise at different rates of metabolic heat production (200, 350, 500 W) at a fixed air temperature (30°C), or exercised at a fixed rate of metabolic heat production (290 W) at different air temperatures (30°C, 35°C, 40°C). Whole‐body sudomotor activity (i.e. evaporative heat loss, E sk ) was measured directly by calorimetry. Stepwise multiple regression analysis revealed that end‐exercise values of E req significantly correlated with the variability in end‐exercise values of E sk (p<0.001), while %VO 2max did not (p=0.690). Independently, end‐exercise E req explained ~95% of the variance in end‐exercise E sk values (adjusted R 2 =0.945). These data provide clear evidence that steady‐state sweat production during exercise is determined by E req , not percent of VO 2max . Supported by NSERC grant RGPIN‐298159–2009 (held by GP Kenny).