Evaluation of specific strength and power at the lower extremity of jumpers using the rebound jump test

Abstract

We aimed to investigate the characteristics of lower-limb strength and power used for lower-limb mechanical variables in rebound jump (RJ) test by using a new system (Quick Motion Analysis System), which calculates mechanical variables in real time. Thirty-three Male jumpers performed the RJ test. The performance (RJ index, contact time, and jump height) and joint kinetics (joint work and joint contribution) in RJ were calculated. IAAF Scoring Tables of Athletics were used to calculate jump event performance (IAAF score). IAAF score was positive correlated with RJ index, jump height, and joint work at the ankle and hip joints. Elite jumpers achieved higher RJ performance by larger ankle and hip joint work. As performance variables, jumping height and contact time were converted to T scores, and evaluation method was proposed to use the relative merits of these values to classify athletes into four types. The IAAF score showed no differences among the four types. These results indicate that there is no relation among jump events performance and characteristics of the four types. Moreover, focusing on stiffness, based on the contact time and jump height, jumpers with a longer contact time and higher jump height type showed lower stiffness (compliant spring characteristics), whereas those with the opposite features showed higher stiffness (stiffer spring characteristics). Therefore, for evaluating lower-limb strength and power characteristics, the use of performance and joint kinetics are effective, in addition to focusing on type characteristics based on the contact time and jump height in RJ.