Contribution of arm movement to the force components of a maximum vertical jump.

Vertical jump is used commonly as a measure of leg power for evaluation prior to participation in sports activities (RK Gray, KB Start, DJ Glencross, Res Q 33:230-235, 1962; DO Klotz, Doctoral dissertation, University of Iowa, 1948). Unless vertical jump meets the definition of mechanical leg power, it should not be used as a measure of leg power. Measurement of leg power in a vertical jump should not be started with a countermovement of the arms prior to jumping. The purpose of this research was to investigate the kinetic and kinematic contributions of arm movement to the vertical jump. Eighteen subjects performed three vertical jumps on a force platform with arm movement and three jumps without arm movement. The contribution of arm movement to maximum force, work done, power, and the release velocity was found as 6, 14, 15, and 6%, respectively, for this population. The contribution of the arm action to reduce the impact force was 12%. The contribution of arm movement to vertical jump maximum force in this study was less than reported in previous studies. J Orthop Sports Phys Ther 1989;11(5):198-201.