EFFECT OF HABITUAL EXERCISE ON DAILY ENERGY-EXPENDITURE AND METABOLIC-RATE DURING STANDARDIZED ACTIVITY

To assess whether long-term habitual exercise affects energy expenditu re even on a nontraining day, 24-h energy expenditure (24-h EE) and me tabolic rate of sedentary, moderately active, and highly active males (n=10 per matched group), were measured in a room respirometer on two separate occasions: sedentary and standardized mild-exercise protocols . Twenty-four-hour EE was greatest in the highly active group, second highest in the moderately active group, and lowest in the sedentary gr oup on both experimental days (sedentary day: 9908 +/-344, 9328+/-357, and 8669+/-227 kJ/d; exercise day: 11915+/-395, 11609+/-328, and 1106 3+/-370 kJ/d, respectively). Differences were significant between the 24-h EE (P<0.01), waking (P<0.03), and sleeping metabolic rate (P<0.01 ) of the highly active group compared with the sedentary group. Howeve r, when expressed per unit lean body mass (LBM), group values on both experimental days were not significantly different. Therefore, we foun d no evidence that habitual exercise, at a high or moderate level, lea ds to a significant prolonged stimulation of metabolic rate per unit a ctive tissue. However, the increased LBM associated with exercise does increase daily energy expenditure by 8-14%.