Effects of an acute bout of aerobic exercise on immediate and subsequent three-day food intake and energy expenditure in active and inactive men

This study examined the effects of an acute bout of low-intensity cycling on food intake and energy expenditure over four days. Thirty healthy, active (n=15) and inactive (n=15) men completed two conditions (exercise and control), in a randomised crossover fashion. The exercise experimental day involved cycling for one hour at an intensity equivalent to 50% of maximum oxygen uptake and two hours of rest. The control condition comprised three hours of rest. Participants arrived at the laboratory fasted overnight; breakfast was standardised and an ad libitum pasta lunch was consumed on each experimental day. Participants kept a food diary and wore an Actiheart to estimate energy intake and expenditure for the remainder of the experimental days and over the subsequent 3days. Ad libitum lunch energy intake did not differ between conditions (p=0.32, d=0.18) or groups (p=0.43, d=0.27). Energy intake in the active group was greater on the exercise experimental day than on the control experimental day (mean difference=2070kJ; 95% CI 397 to 3743kJ, p=0.024, d=0.56) while in the inactive group it was increased on only the third day after exercise (mean difference=2225kJ; 95% CI 414 to 4036kJ, p=0.024, d=0.80). There was only a group effect (p=0.032, d=0.89) for free-living energy expenditure, indicating that active participants expended more energy than inactive over this period. Acute low-intensity exercise did not affect energy intake at the meal immediately after exercise, but induces an acute (within the experimental day) and delayed (third day after the experimental day) increase in energy intake in active and inactive participants, respectively with no compensatory changes to daily energy expenditure. These results suggest that active individuals compensate for an acute exercise-induced energy deficit quicker than inactive individuals.