Comparative Effects of Deep Versus Shallow Squat and Leg-Press Training on Vertical Jumping Ability and Related Factors

Abstract

Young, previously untrained healthy men (n = 10) and women (n = 8) completed 9 weeks of periodized, machine-based squat training to determine if manipulating range of motion would have a differential effect on vertical jumping ability and related measures. Subjects were pretested and then randomly assigned to 1 of 3 groups: (a) deep squats (n = 6), (b) shallow squats (n = 6), and (c) controls (n = 6). Training took place 3 days per week. Pre-and posttesting included standing (RVJ) and depth (DVJ) vertical jumps for distance; machine deep and shallow squats for 1RM (1 repetition maximum) relative strength; and velocity-controlled squats at 0.51 m·s−1 for relative peak force and at 1.43 m·s−1 for relative peak power. Based on ANCOVA posttest results, the training protocols were ineffective in eliciting improved performance (p > 0.05) in VJ, slow-velocity squatting force, and moderately fast squatting power when performance was compared with the performance of control subjects. Conversely, the group training with deep squats was the only group to perform significantly (p <0.05) better than controls for 1RM shallow squats and significantly (p <0.05) better than both shallow-squat and control groups for 1RM deep squats. Furthermore, the coefficient of transfer for deep squats to both RVJ (2.32) and DVJ (1.68) was substantially greater than for shallow squats (0.31 and 0.11, respectively). It was concluded that deep-squat training appears to elicit the best improvement for both shallow-and deep-squatting performance. However, 9 weeks of machine-based, periodized squat training, regardless of depth, does not appear to appreciably enhance slow-velocity squatting force, moderately fast squatting power, or vertical jumping distance in previously untrained men and women.