PURPOSE: We examined whether continuous and intermittent physical activity (PA) differentially influence fat utilization. METHODS: This was a randomized crossover study. Nine healthy young male participants performed two 39-h (two nights, three days) PA sessions (continuous and intermittent exercise) in a respiratory chamber to measure energy expenditure (EE) and substrate oxidation. Participants used a stationary cycling ergometer continuously for 40 min and then 45 min in the continuous PA trial and for 5 min every 30 min 17 times in the intermittent PA trial. They consumed high-carbohydrate meals corresponding to predicted daily total EE for 3 d before entering the respiratory chamber and four high-fat meals corresponding to predicted total EE in the chamber. RESULTS: Twenty-three-hour RER adjusted for sleeping RER on the preceding day was significantly lower in the intermittent PA trial than that in the continuous PA trial (P = 0.021). Twenty-three-hour RER adjusted for sleeping RER on the preceding day was correlated with accumulated consecutive minutes of METs ≤1.5 (3 min or more, r = 0.477; 5 min or more, r = 0.510; 10 min or more, r = 0.605). CONCLUSIONS: The intermittent PA trial induced greater fat utilization than the continuous PA trial. The present study, therefore, suggests that intermittent PA has a beneficial effect on 24-h fat oxidation after consumption of a high-fat meal, which may help prevent weight gain over time.
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