A 45-minute vigorous exercise bout increases metabolic rate for 14 hours.

INTRODUCTION The magnitude and duration of the elevation in resting energy expenditure after vigorous exercise have not been measured in a metabolic chamber. This study investigated the effects of inserting a 45-min vigorous cycling bout into the daily schedule versus a controlled resting day on 24-h energy expenditure in a metabolic chamber. METHODS Ten male subjects (age = 22-33 yr) completed two separate 24-h chamber visits (one rest and one exercise day), and energy balance was maintained for each visit condition. On the exercise day, subjects completed 45 min of cycling at 57% Wmax (mean ± SD = 72.8% ± 5.8% VO(2)max) starting at 11:00 a.m. Activities of daily living were tightly controlled to ensure uniformity on both rest and exercise days. The area under the energy expenditure curve for exercise and rest days was calculated using the trapezoid rule in the EXPAND procedure in the SAS and then contrasted. RESULTS The 45-min exercise bout resulted in a net energy expenditure of 519 ± 60.9 kcal (P < 0.001). For 14 h after exercise, energy expenditure was increased 190 ± 71.4 kcal compared with the rest day (P < 0.001). CONCLUSIONS In young male subjects, vigorous exercise for 45 min resulted in a significant elevation in postexercise energy expenditure that persisted for 14 h. The 190 kcal expended after exercise above resting levels represented an additional 37% to the net energy expended during the 45-min cycling bout. The magnitude and duration of increased energy expenditure after a 45-min bout of vigorous exercise may have implications for weight loss and management.