DiVerential eVects of countermovement magnitude and volitional eVort on vertical jumping

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Abstract

The importance of vertical jumping in sport and rehabilitative medicine is widely recognized. Despite the ample use of jump tests to assess neuromuscular function, the diVerential eVects of muscular activation (volitional eVort) and strategy (countermovement magnitude) on jumping performance have not been studied. The present study aimed to investigate the diVerential eVects of countermovement magnitude and volitional eVort on vertical jump performance. Ten male participants performed a total of 60 countermovement jumps each with three diVerent countermovement knee angles (50, 70 and 90°) and four eVort levels (25, 50, 75 and 100% of maximal eVort). Kinematics and Kinetics were recorded using Vicon System together with a force platform. Electromyography of four muscles was recorded. Results show that countermovement magnitude and volitional eVort both aVect jump performance. These eVects were synergistic for jump height (P < 0.001), but antagonistic for peak ground reaction force (P < 0.001). Interestingly, peak jump mechanical power was aVected by volitional eVort, implying an increase from 31.26 W/kg at 25% to 41.68 W/kg at 100% of volitional eVort, but no countermovement magnitude eVect was observed for 100% of volitional eVort. This suggests that the apparent paradox of larger ground reaction forces in sub-maximal as compared to maximal jumps is due to the diVerent jump strategies. Moreover, these results are relevant for jumping mechanography as a clinical tool, suggesting that peak power can be used to assess neuromuscular performance even when countermovement magnitude varies as a result of age or pathology.

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• DiVerential eVects of countermovement magnitude and volitional eVort on vertical jumping. (deposited 27 Jun 2011 09:21) [Currently Displayed]