Comparison of the Effect of Hot and Thermo-Neutral Environments on Fat Oxidation during Post-Exercise Recovery in Exercise-Trained Obese Women: A Preliminary Report

Exercise training is recommended to promote energy expenditure. Fat utilization occurs during exercise and continues for an extended period of time after the exercise session. The environmental temperatures can influence whole body substrate oxidation. The present study aimed to address the impacts of environmental temperature on fat oxidation during post-exercise recovery in exercise-trained obese women. Eleven sedentary obese women (age: 18 - 50 y, BMI: 27.5 - 40 kg/m2) with regular menstruation participated in the study. All subjects underwent a 4-week moderate-intensity aerobic exercise program. After training, each subject completed 2 occasions of post-exercise recovery testing in hot (31 - 32 °C) and thermo-neutral (22 - 23 °C) conditions in a randomized crossover fashion with 3 - 4 days of washout period. Two exercise bouts preceding each recovery condition were identically performed for 60 min at 60 % of heart rate reserve (HRreserve) in the thermo-neutral condition. Both experiments were conducted during the follicular phase of menstrual cycle. Substrate oxidations were determined during 1 h of post-exercise recovery using indirect calorimetry. The results showed that the fat oxidation during recovery in thermo-neutral environment (52.8 ± 26.5 mg.kg-1.h-1) was significantly greater than recovery in hot environment (32.3 ± 27.9 mg.kg-1.h-1, p = 0.0002). Total energy from substrate oxidation was not different between hot and thermo-neutral environments. Thus, in obese women with 4-week exercise training, recovery in the thermo-neutral condition has a higher fat oxidation than in the hot condition. This result may be implicated in weight management for temperature of choice to recover after routine exercise training sessions. HIGHLIGHTS Fat oxidation was greater during recovery in thermo-neutral environment after moderate-intensity exercise in trained obese women Recovery carbohydrate oxidation was greater in hot environment than in thermo-neutral environment after moderate-intensity exercise Energy expenditure from substrate oxidations during recovery in both thermo-neutral and hot environments were similar GRAPHICAL ABSTRACT