Influences of a Cold and Warm Environment on Substrate Metabolism in Women during Running and Cycling
Authors: Gagnon Dominique D. , McCue Alexus , Dorman Sandra C. , Serresse Olivier 
Published: June 2021

BackgroundWomen oxidize more fat than men at rest and during exercise due to differences in hormonal and blood flow regulatory mechanisms, as well as substrate storage and mobilization. Exercise studies examining the effects of varying environments on energy metabolism have consistently demonstrated a greater shift towards lipid utilization in cold compared to warm environments in men. In addition, these studies have been conducted at fixed exercise intensities and workloads only, and have not been validated with different exercise modalities. Thereby, this study aimed to determine whether cold and warm ambient temperatures influence fat and CHO oxidation across a range of exercise intensities during treadmill and cycle ergometer exercise in women.MethodsTwelve women (age 22 ± 1.8 yrs, weight 61 ± 6.6 kg, height 1.6 ± 0.09 m, body fat 26 ± 4.7 %, FFM 45 ± 5.8 kg, body surface area 1.6 ± 0.12 m2, and V̇O2 48 ± 5.1 mlO2·kg−1·min−1) completed four trials, one week apart, during which they performed an incremental peak oxygen consumption (V̇O2peak) test on a cycle ergometer or treadmill in a cold (5°C) or warm (35°C) environment. Cardiorespiratory and oxidation variables, including V̇O2, maximal fat oxidation rate (MFO), exercise intensity where MFO occurs (Fatmax), and relative contribution of lipids and carbohydrates (CHO) to total energy expenditure crossover point (CC) were assessed via indirect calorimetry. Lactate pre and post tests was also assessed. Analyses of variances and multiple linear regressions were performed.ResultsMFO was greater in the cold vs. warm for treadmill (0.51 ± 0.19 vs. 0.41 ± 0.14 g•min−1; p=0.04) but not during cycling (0.32 ± 0.14 vs. 0.23 ± 0.07 g•min−1; p=0.08). MFO was also greater during treadmill vs. cycling exercise, in both temperatures (0.46 ± 0.16 g•min−1 vs. 0.28 ± 0.11 g•min−1; p<0.001). Fatmax was greater in the cold vs. warm within treadmill (63 ± 27 vs. 49 ± 22 % V̇O2max; p=0.02) but not cycling (41 ± 20 vs. 31 ± 12 % V̇O2max; p=0.16). CC was greater in the cold vs. warm within treadmill exercise (53 ± 20 vs. 39 ± 17% V̇O2max; p=0.04) but not during cycling (36 ± 12 vs. 28 ± 10% V̇O2max; p=0.19). Multiple linear regressions further revealed a strong influence of ambient temperature on lipids (p<0.001) and CHO (p<0.001) oxidation rates across exercise intensities.ConclusionsExercising in a cold environment increased MFO, Fatmax, and CC during treadmill exercise in women but not during cycling. These results imply that ambient temperature influences energy metabolism over a wide range of exercise intensities during treadmill exercise in women, similarly to what is seen in men. The large variability in fat oxidation in the present results, similar to other studies, will need to be investigated further in both women and men.Support or Funding InformationThis work was supported by a Laurentian University Research Fund grant.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.