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Work characteristics of standing broad and vertical jumping

University of British Columbia

The purpose of this study was to determine the contributions made by the leg muscle groups to the work done in standing broad and vertical jumping. A secondary purpose was to examine the principles of summation and continuity of joint forces as they apply to these jumps. Twelve subjects were filmed while jumping from a force platform. They performed a minimum of three maximal standing broad and vertical jumps, with countermovements and use of the arms permitted. The jumps were filmed at a rate of 50 frames per second while, synchronously, ground reaction force data were collected at 50 Hz. Link segment analysis and inverse dynamics methods were used to compute the net muscle moments of force and the power and work outputs created by these moments of force. The jumps were examined over two time periods, during both the propulsive phase of jumping and the entire jump. The work-energy approach was used to determine the relative contributions of the muscles crossing the ankle, knee and hip joints to the total work done at the leg joints. A work-energy analysis (i.e. the ratio of net mechanical work done at 6 joints to the gain in total mechanical energy) for the two types of jumps during the two time intervals of interest produced values all less than 1.0. This suggests that there were other sources of work that subjects were using and which were not measured in the analysis. As well, this suggests that the link segment model utilized may not have been appropriate for all subjects. For the standing broad jump the contributions of the ankle, knee and hip muscles during the propulsive phase were 30.2, 18.6 and 51.2 percent, respectively, while their contributions over the entire jump were 31.5, 17.0 and 51.5 percent, respectively. The respective contributions of the ankle, knee and hip joints for the vertical jump during the propulsive phase were 33.0, 24.8 and 42.2 percent and over the entire jump the contributions were 39.2 (ankle), 22.4 (knee) and 38.4 (hip) percent. Two-tailed correlated t-tests were done to check for differences in relative contributions of both the ankle and knee joints to the work done at the leg joints in standing broad and vertical jumping. The only significant difference (p<.01) occurred at the ankle joint over the entire jump. Relatively, the muscles crossing the ankle joint did significantly more work in vertical jumping than in standing broad jumping. One-way ANOVAs with repeated measures were utilized to test the differences between relative joint contributions for each type of jump during the two time periods examined. Neuman-Keuls post hoc method was used to evaluate the multiple pairwise comparisons. There were two main findings. First, over the entire jump, the muscles crossing the hip joint did significantly more work than those of the knee joint during both standing broad (p<.01) and vertical jumping (p<.05). Then for the propulsive phase, there was significantly more work generated at the hip joint than at either the knee joint or the ankle joint during both vertical jumping (knee: p<.01; ankle: p<.05) and standing broad jumping (knee: p<.01; ankle: p<.01). Results for the evaluation of the summation and continuity principles supported the principle of summation of joint forces as the muscles of all three leg joints, for all subjects, were net generators of positive work during the propulsive phase of standing broad and vertical jumping. The continuity of joint forces principle, however, was not fully supported as the sequencing of muscular contractions was not always from proximal to distal as expected.

Text

2010-07-12

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http://hdl.handle.net/2429/26351

Physical Education

University of British Columbia

Graduate