Document Detail

Large differences in peak oxygen uptake do not independently alter changes in core temperature and sweating during exercise.
MedLine Citation:
PMID:  21697517     Owner:  NLM     Status:  Publisher    
The independent influence of peak oxygen uptake (VO(2peak)) on changes in thermoregulatory responses during exercise in a neutral climate has not been previously isolated due to complex interactions between VO(2peak), metabolic heat production (H(prod)), body mass and surface area (BSA). It was hypothesized that VO(2peak) does not independently alter changes in core temperature and sweating during exercise. Fourteen males, 7 high (HI) VO(2peak):60.1±4.5 mL⋅kg/min; 7 low (LO) VO(2peak):40.3±2.9 mL⋅kg⋅min matched for body mass (HI:78.2±6.1kg; LO:78.7±7.1kg) and BSA (HI:1.97±0.08m2; LO:1.94±0.08m(2)), cycled for 60-min at 1) a fixed heat production (FHP trial); and 2) a relative exercise intensity of 60% VO(2peak) (REL trial) at 24.8±0.6°C, 26±10%RH. In the FHP trial, H(prod) was similar between the HI (542±38W, 7.0±0.6W/kg or 275±25W⋅m(2)) and LO (535±39W, 6.9±0.9W⋅kg or 277±29W/m2) groups, while changes in rectal (T(re):HI:0.87±0.15°C, LO:0.87±0.18°C, P=1.00) and aural canal (T(au): HI:0.70{±0.12°C, LO:0.74±0.21°C, P=0.65) temperature, whole-body sweat loss (WBSL) (HI:434±80 mL, LO:440±41 mL; P=0.86), and steady-state local sweating (LSRback) (P=0.40) were all similar despite relative exercise intensity being different (HI:39.7±4.2%, LO:57.6±8.0% VO(2peak); P=0.001). At 60% VO(2peak), H(prod) was greater in the HI (834±77 W, 10.7±1.3 W⋅kg or 423±44 W⋅m(2)) compared to LO (600±90 W, 7.7±1.4 W⋅kg or 310±50 W⋅m(2)) group (all P<0.001), as were changes in T(re) (HI:1.43±0.28°C, LO:0.89±0.19°C; P=0.001) and T(au) (HI:1.11±0.21°C, LO:0.66±0.14°C; P<0.001), and WBSL between 0-15, 15-30, 30-45 and 45-60 minutes (all P<0.01), and LSR(back) (P=0.02). The absolute esophageal temperature (T(es)) onset for sudomotor activity was ~0.3°C lower (P<0.05) in the HI group, but the change in T(es) from pre-exercise values before sweating onset was similar between groups. Sudomotor thermosensitivity during exercise were similar in both FHP (P=0.22) and REL (P=0.77) trials. In conclusion, changes in core temperature and sweating during exercise in a neutral climate are determined by H(prod), mass and BSA, not VO(2peak).
Ollie Jay; Anthony R Bain; Tomasz M Deren; Matthew Sacheli; Matthew N Cramer
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-6-22
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  -     ISSN:  1522-1490     ISO Abbreviation:  -     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-6-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
1University of Ottawa.
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