Background/Purpose There is abundant research about biomechanical variables associated with jump landings. Neuromechanical parameters associated with take-off during repetitive jumping activity have been minimally investigated. The purpose of this study was to examine relationships among repetitive jumping and: gender, sport type, and lower extremity EMG activity at take-off.
Method Student-athletes (ages 19-24) from male and female intercollegiate teams (N=24) performed 30 vertical jumps with a 1 sec. rest between each jump. An integrated motion capture/EMG system was used to measure activity of eight lower extremity muscles at jumps 1, 15, and 30. Surface electrodes were used to measure the activity (amplitude and frequency) from the greatest depth of knee flexion to toe-off. Data were analyzed using repeated measures one-way ANOVA and a Tukey post hoc test when significance was found.
Analysis/Results No differences were found between the number of the jump and gender and sport type. The amplitude and frequency of the medial head of gastrocnemius increased significantly p<.01) as the number of jumps increased. The lateral head of gastrocnemius showed a trend for increased amplitude and frequency (p<.05) with increased jump repetition. Correlation showed a strong positive relationship between amplitude of the medial head of the gastrocnemius and the number of jumps (r =.902).
Conclusions Results provide evidence that as number of jumping repetitions increase, EMG activity increases primarily in the medial and lateral heads of gastrocnemius. It is recommended that future study include analysis of maximum height of peak center of mass, EMG activity, and jump repetition.