Tran, T. T., Brown, L. E., Coburn, J. W., Lynn, S. K., Dabbs, N. C., Gochioco, M. K., Schick, E. E., Khamoui, A. V., Uribe, B. P., & Noffal, G. J. (June 02, 2010). Effects of different levels of assisted jumping on vertical jump height and relative ground reaction force. Presentation 1705 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

This study examined different assisted jump conditions on vertical jump height and relative ground reaction force in recreationally trained college students (N = 20). Ss completed three testing sessions, consisting of a 5-minute warm-up, followed by randomized experimental conditions of 0%, 10%, 20%, 30%, and 40% body weight reduction. In all body weight reduction experimental sessions, Ss wore a full body harness while attached to two elastic cords, which were attached to the ceiling. Ss performed three maximal counter-movement jumps with arm swing for all conditions on a force plate. One minute of rest was given between each jump and two minutes of rest were provided between conditions. Maximum values from the peak velocity repetition for each condition were used for analysis.

There was no interaction of condition by sex for either variable. There were significant main effects for condition for both variables. As body weight reduction increased, vertical jump height and relative ground reaction force significantly increased with the exception of 0% and 10%. Significant increases were found between all other body weight reduction conditions for vertical jump height and relative ground reaction force.

Implication. Body weight reductions of 20%, 30% and 40% using elastic cords increases vertical jump height and relative ground reaction force. The use of elastic cords in this way could improve jumping in average performers. There are no grounds for inferring that the use of cords will improve performance in elite jumpers.

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