Influence of the intensity of squat exercises on the subsequent jump performance.

Jump performance can be enhanced after performing squat exercises, and this is thought to be because of the phenomenon of postactivation potentiation (PAP). However, the influence of the intensity of squat exercises on jump performance enhancement and its association to PAP have not been elucidated. Thus, we examined the influence of the intensity of squat exercises on the subsequent jump performance and the magnitude of PAP. Eight weightlifters (age, 19.8 ± 1.3 years; height, 1.67 ± 0.07 m; body mass, 77.1 ± 14.8 kg) were recruited as subjects. The intensity of squat exercises was set in 2 conditions: heavy condition (HC) (45% 1 repetition maximum [1RM] × 5 repetitions [reps], 60% 1RM × 5 reps, 75% 1RM × 3 reps, and 90% 1RM × 3 reps) and moderate condition (MC) (45% 1RM × 5 reps, 60% 1RM × 5 reps, and 75% 1RM × 3 reps). Before and after the squat exercises, the subjects performed countermovement jumps 3 times. In addition, a twitch contraction was concurrently elicited before and after the squat exercises. In both conditions, twitch torque and jump height recorded after the squat exercises increased significantly compared with those recorded beforehand. The extents of increase in both twitch torque and jump height were significantly larger in HC than in MC. We conclude therefore that a high-intensity squat exercise is better than a moderate-intensity squat exercise as a warm-up modality for enhancing subsequent jump performance.