Effects of reduced ambient temperature on fat utilization during submaximal exercise
Research output: Contribution to journal › Article › peer-review
Authors
Colleges, School and Institutes
Abstract
PURPOSE: The influence of cold air exposure on fuel utilization during prolonged cycle exercise was investigated.
METHODS: Nine male subjects cycled for 90 min in ambient temperatures of -10 degrees C, 0 degrees C, 10 degrees C, and 20 degrees C. External work performed between conditions was constant. Mean oxygen consumption (VO2) over the 90 min in the 20 degrees C trial corresponded to 64 +/- 5.8% VO2peak.
RESULTS: Although mean skin temperature was different between trials (P < 0.05), rectal temperatures were not different. At -10 degrees C and 0 degrees C, the respiratory exchange ratio was higher compared with 10 degrees C and 20 degrees C (0.98 +/- 0.01 and 0.97 +/- 0.01 vs 0.92 +/- 0.01 and 0.91 +/- 0.01; P < 0.05). The associated rates of fat oxidation were lower at -10 degrees C and 0 degrees C compared with 10 degrees C and 20 degrees C (0.15 +/- 0.06 and 0.17 +/- 0.06 vs 0.35 +/- 0.06 and 0.40 +/- 0.04 g.min-1; P < 0.05). Blood glycerol was lower at -10 degrees C and 0 degrees C compared with 20 degrees C (P < 0.05); mean values were 0.13 +/- 0.0, 0.13 +/- 0.0, and 0.18 +/- 0.0 mmol.L-1 for the -10 degrees C, 0 degrees C, and 20 degrees C trials, respectively. Mean VO2 was lower in the -10 degrees C trial than the 20 degrees C trial (2.53 +/- 0.06 vs 2.77 +/- 0.09. L.min-1; P < 0.05). Mean blood glucose concentrations were lower at -10 degrees C than 20 degrees C (4.9 +/- 0.2 vs 5.3 +/- 0.1 mmol.L-1; P < 0.05). Although plasma epinephrine concentrations were greater during the 20 degrees C trial compared with all other trials (P < 0.05), plasma norepinephrine did not differ between trials.
CONCLUSION: The diminished fat oxidation at colder temperatures potentially reflects a reduction in lipolysis and/or mobilization of FFA or impairment in the oxidative capacity of the muscle.
Details
Original language | English |
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Pages (from-to) | 774-9 |
Number of pages | 6 |
Journal | Medicine and Science in Sports and Exercise |
Volume | 34 |
Issue number | 5 |
Publication status | Published - May 2002 |
Keywords
- Adipose Tissue, Adult, Anaerobic Threshold, Analysis of Variance, Bicycling, Body Temperature, Cold Climate, Energy Metabolism, Exercise, Fatty Acids, Nonesterified, Heart Rate, Humans, Lipid Metabolism, Lipids, Male, Pulmonary Gas Exchange, Time Factors