Differences in the characteristics of 3-dimensional joint kinetics between single-leg and double-leg rebound jump

Abstract

This study aimed to clarify the 3-dimensional joint kinetics of the takeoŠleg for the single-leg rebound jump (SRJ) and the double-leg rebound jump (DRJ). 14 male track and ˆeld athletes (sprin- ters, jumpers and decathletes) performed the SRJ and the DRJ with maximal eŠort. Kinematics and ki- netics data were recorded using a Vicon T20 system (250 Hz) and force platforms (1000 Hz).The results of all the analyses were as follows: 1. In the SRJ, hip joint work around the adduction-abduction and internal-external rotation axes was higher than in the DRJ, because of larger hip abduction and internal rotational torque in the SRJ. 2. In the SRJ, hip abduction and internal rotation torque were larger than those in the DRJ. These may have been caused by the anatomical and mechanical diŠerences between the SRJ and DRJ. 3. In the SRJ, hip abduction torque aŠected the increment in jump height. This result suggests that hip abduction torque aŠects the higher jump height for a single leg to a greater extent in the SRJ than in the DRJ. 4. In the SRJ, the trunk lateral ‰exion caused by trunk ‰exion torque reduced the lateral displacement of the center of gravity due to pelvic list. These results suggest that 1) the SRJ is an eŠective training tool for improvement of technique and force output ability for prioritization of power output at the hip internal rotators, especially the hip abduc- tors in addition to the hip extensor, and 2) hip abduction torque in the SRJ has a role in both postural con- trol and determining the increment in jump height. These ˆndings will be useful for clarifying the most pertinent points related to the SRJ and for developing an eŠective method that can be applied to plyomet- rics.