UBC Theses and Dissertations
The comparative effects on vertical jump of three different depth jump programs Hawkins, Francis John Alexander
The purpose of this study was to investigate which factor in depth jumping, landing momentum or landing velocity, is the more effective in improving vertical jump. Three depth jump training conditions were utilized: a high velocity, high momentum condition in which the subjects (n=10) jumped unloaded from their individual optimum heights (the height where their rebound height equaled the height jumped from); a low velocity, high momentum condition in which the subjects (n=10) jumped wearing weight jackets that weighed 15% of their body weight from heights that resulted in their landing momenta being equal to their calculated landing momenta had they been performing the high velocity, high momentum conditions; and a medium velocity, low momentum condition in which the subjects (n=8) jumped unloaded from heights midway between their optimum heights and their calculated jump heights had they been performing the low velocity, high momentum condition. Twenty-eight male members of University of British Columbia athletic teams volunteered as subjects. Each team was divided equally between, but individual team members assigned randomly to, each of the three experimental conditions. The depth jump programs consisted of four sets of eight jumps twice a week for the first three weeks and five sets of eight jumps three times a week for the last three weeks. All subjects were tested at the beginning, middle and end of the study on the Sargeant Jump Test, Standard Depth Jump Test (performed from an 18 in platform). Knee Extension Strength Test and Plantar Flexion Strength Test. Multivariate analysis of variance revealed that performance of all three training conditions resulted in improvement of vertical jump, standard depth jump and plantar flexion strength (all significant at the .01 level) and that there were no significant differences between the conditions in improvement on these measures. No significant improvement was seen in knee extension strength in any of the conditions. Pearson Product Moment Correlation of the four variables showed that there were strong correlations between sargeant jump and standard depth jump (significant at the .01 level) and between knee extension strength and plantar flexion strength (significant at the .05 level)-but no significant correlations between the jump and strength measures. At the end of the study a force platform was utilized to record the reaction force characteristics of eight subjects while they performed jumps under each of the three training conditions. Multivariate analysis of variance of the data revealed significant differences between the conditions on the impulse variables and no significant differences between the conditions on time or force variables. Post-hoc Newman-Kuels multiple comparison tests revealed that the impulses of the subjects when jumping under the low velocity, high momentum condition were significantly greater (at the .05 level) than the impulses recorded when the subjects were jumping in the other two conditions (which were not significantly different from each other). The results of this study did not indicate clearly which factor in depth jumping, landing momentum or landing velocity, was more effective in improving vertical jump.
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