An investigation of the influence of bi-lateral deficit on human jumping

The purpose of this study was to investigate the influence of bi-lateral deficit on one- and two-legged maximal vertical jumps, Seven female subjects (height 1.68 +/- 0.03 m, mass 64.39 +/- 6.93 kg) performed maximum vertical jumps with no counter movement from their preferred jumping leg and from both legs. Force plate and video analysis were used to determine the kinematics and kinetics of the activity. The minimum and maximum ankle, knee and hip joint angles for the two jump conditions were not significantly different, indicating similar ranges of motion used in both types of jump. The height jumped from one leg was significantly different from being 50% of that jumped from two legs; the height jumped from one leg was 58.1% of that jumped from two. The general pattern of the angular velocities and resultant joint moments in these jumps indicated that the sequencing of joint extensions was similar regardless of jump condition. A simple model of jumping was presented. Simulations of one-and two-legged jumping, using the model, indicated that the bi-lateral deficit was predominantly responsible for the differences in jump heights observed experimentally. (C) 1998 Elsevier Science B.V. All rights reserved.