Abstract
Previous studies suggest that terminating resistance exercise sets short of failure can produce muscle hypertrophy comparable to training to failure; however, its effects on post-exercise energy metabolism remain unclear. This study examined how progressively increasing repetitions and reaching failure affect the magnitude and duration of excess post-exercise oxygen consumption (EPOC) and post-exercise energy expenditure at a fixed relative intensity. Eight resistance-trained male university students performed three randomized squat conditions at 75% one-repetition maximum (1RM) for three sets: 4 repetitions, 8 repetitions, and repetitions to failure (All-out). Oxygen uptake, heart rate, blood lactate concentration, and rating of perceived exertion were measured during exercise and for 120 min afterward. EPOC and excess post-exercise energy expenditure (EPEE) were calculated from post-exercise oxygen uptake. Oxygen uptake, energy expenditure, blood lactate concentration, heart rate, and rating of perceived exertion during exercise increased significantly in the order 4 reps < 8 reps < All-out (all P < 0.05). EPOC remained elevated for 35 min, 70 min, and throughout the 120-min observation period in the 4 reps, 8 reps, and All-out conditions, respectively. Total EPOC and EPEE were significantly greater in the same order (all P < 0.05; η²p = 0.82–0.85). When EPOC was normalized to total exercise volume, the differences among conditions were no longer significant, indicating that the greater EPOC after training to failure was largely due to the greater exercise volume; in contrast, EPOC duration was disproportionately prolonged. Non-failure exercise produced smaller, dose-dependent increases in EPOC, indicating a lower post-exercise energy cost.
