Comparison of hard and soft surfaces during maximal vertical jumps in a depth jump plyometric exercise

Abstract

The purpose of this study was to examine how landing surfaces used in a depth jumping (DJ) plyometric exercise affected kinematic and kinetic variables. Sixteen male and female college students, who were involved in recreational activities, performed 5 DJ onto a force platform alone (hard landing surface) and a 2.35cm thick mat placed onto the force platform (soft landing surface). The maximum angular position and angular velocity measurements were recorded and analyzed for the trunk segment and knee joint at the greatest point of knee flexion during landing using a video camera and an Ariel Performance Analysis System (APAS). Contact and flight times were established using data collected by a Bertec force platform. The vertical ground reaction forces and the rate at which these forces were generated were collected and analyzed between surface conditions. An alpha level of 0.05 was used in all statistical tests. A t-test was used for all statistical analyses. Results indicated no significant differences in the maximum angular positions of knee and trunk segments at landing (p = 0.424 and 0.266, respectively). Angular velocities of the knee and trunk segment at landing were not significant (p = 0.153 and 0.243, respectively). The contact and flight times were found to be nonsignificant (p = 0.263 and 0.397, respectively). The time to peak vertical ground reaction force was also found to be nonsignificant (p = 0.224). From the results, it can be concluded that a soft landing surface, 2.35cm thick, would be as effective at eliciting the desired traits (decreased joint flexion, decreased contact time, and increased flight time) of the DJ exercise as a hard landing surface.