A Biomechanical Analysis of the Vertical Jump and Three Modified Plyometric Depth Jumps

Abstract

Plyometrics are recommended for increasing strength and power. The plyometric depth jump (DJ involves the hip extensors far less than the countermovement jump (CM), thus DJ may not adequately train the hip extensors. This research sought to develop a DJ that would demand more from the hip extensors. Specific jumps were also developed for the ankle and knee extensors. Subjects, 11 college-age men, performed CMJ and DJ from a height of 50 cm. Data were collected to determine net joint moments, power, and work about the joints. Variables were calculated during the down and up phases and for the entire jump. Maximum moment and power values were calculated for each joint. ANOVAs were used to compare the selected variables from DJ to the corresponding variables in CMJ. All variables from the selected joints were greater with DJ, and 29 of the 33 comparisons were significantly different (p ≤ 0.05). The corresponding joint moments for ankle, knee, and hip depth jumps were significantly greater than for CMJ. The modified plyometric jumps were shown to enhance the contribution of the muscles that extend the ankle, knee, and hip.