Ambient temperature influences metabolic substrate oxidation curves during running and cycling in healthy men

• Published in: European journal of sport science Vol. 20; no. 1; pp. 90 - 99
• Main Authors: Gagnon, Dominique D., Perrier, Lina, Dorman, Sandra C., Oddson, Bruce, Larivière, Céline, Serresse, Olivier
• Format: Journal Article
• Language: English
• Published: England Routledge 02-01-2020
• Subjects: exercise; indirect calorimetry; Substrate oxidation; temperature; temperature; exercise; Substrate oxidation; indirect calorimetry
• ISSN: 1746-1391; 1536-7290
• DOI: 10.1080/17461391.2019.1612949

Fat oxidation in cold environments and carbohydrate (CHO) use in hot environments are increased during exercise at steady-state submaximal workloads. However, the influence of cold and heat on fat and CHO oxidation curves remain unknown. We therefore examined the influence of a cold and warm ambient temperature on fat and CHO oxidation across a wide range of exercise intensities during treadmill and cycle ergometer exercise. Nine, young, healthy, male subjects completed four trials, during which they performed an incremental peak oxygen consumption (⩒O
2peak
) test on a cycle ergometer or treadmill in a 4.6°C or 34.1°C environment. Substrate oxidation, maximal fat oxidation rate (MFO), and exercise intensity where MFO occurs (Fat
max
) were assessed via indirect calorimetry. MFO was significantly greater in the cold vs. warm during the treadmill exercise (0.66 ± 0.31 vs. 0.43 ± 0.23 g min
−1
; p = 0.02) but not during cycling (0.45 ± 0.24 vs. 0.29 ± 0.11 g min
−1
; p = 0.076). MFO was also greater during treadmill vs. cycling exercise, irrespective of ambient temperature (0.57 g min
−1
vs. 0.37 g min
−1
; p = 0.04). Fat
max
was greater in the cold vs. warm for both treadmill (57 ± 20 vs. 37 ± 17%⩒O
2peak
; p = 0.025) and cycling (62 ± 28 vs. 36 ± 13%⩒O
2peak
; p = 0.003). Multiple, linear, mixed-effects regressions revealed a strong influence of ambient temperature on substrate oxidation. We demonstrated that exercising in a cold environment increases MFO and Fat
max
, predominantly during treadmill exercise. These results validate the implication of ambient temperature on energy metabolism over a wide range of exercise intensities.