The effects of rest and exercise in the cold on substrate mobilization and utilization
Hurley, B.F.; Haymes, E.M.
Aviation Space and Environmental Medicine 53(12): 1193-1197
1982
ISSN/ISBN: 0095-6562 PMID: 7159340 Document Number: 187444
Six men 22 to 27 years old rested and exercised in neutral and cold environments to produce a neutral core and neutral skin temperature, a neutral core and cold skin temperature and a cold core and cold skin temperature. Plasma free fatty acid (FFA) and glucose (GL) and in blood lactate (LA), Hb and haematocrit (Hct) concentrations were measured, as were heart rate (HR), respiratory exchange ratio (R) and oxygen consumption after 30, 60 and 90 min of exposure to each condition. FFA, GL, LA, Hb and Hct concentrations increased significantly during rest when mean skin temperature (Tsk) and rectal temperature (Tre) were decreased. Plasma FFA concentration was also significantly increased and R values were decreased during exercise when Tsk and Tre were lower than those during exercise in a neutral environment. No significant difference in substrate concentration, haemoconcentration or R values was observed when Tsk alone was decreased at rest or during exercise. It is concluded that preferential utilization of fat occurs during exercise in the cold when Tsk and Tre are lower than those during exercise in a neutral environment.