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Bilateral Neuromuscular and Force Differences During a Plyometric Task

Ball, Nick B; Scurr, Joanna C

The Journal of Strength & Conditioning Research: August 2009 - Volume 23 - Issue 5 - p 1433-1441
doi: 10.1519/JSC.0b013e3181a4e97f
Original Research

Ball, NB and Scurr, JC. Bilateral neuromuscular and force differences during a plyometric task. J Strength Cond Res 23(5): 1433-1441, 2009-The purpose of this article is to compare the bilateral neuromuscular and force contribution during a plyometric bounce drop jump task and to assess the affects of nonsimultaneous foot placement. Sixteen male participants performed bounce drop jumps from a height of 0.4 m. Mean peak electromyography activity of the soleus, medial, and lateral gastrocnemius of both legs was recorded from each phase of the drop jump and normalized to a reference dynamic muscle action. Resultant ground reaction force, ground contact time, and duration of the drop jumps were recorded from each leg. Multivariate analysis of variance was used to compare bilateral electromyographic activity, resultant peak ground reaction force, and contact duration. Pearson's correlations (r) ascertained relationships between normalized electromyographic activity and contact time. Significant differences were shown between left and right triceps surae normalized electromyography during precontact and contact40ms (p < 0.01). No significant differences were present in the contactpost40ms phase (p > 0.01). Significant differences were found between normalized soleus electromyography and both gastrocnemii for both legs during precontact (p < 0.01). No significant differences were found for within-leg normalized electromyography for the contact40ms phases and contactpost40ms phase (p > 0.01). Weak relationships were found between normalized electromyographic activity and nonsimultaneous foot contact (r < 0.2). This study showed differences between left and right triceps surae in neuromuscular strategies engaged in the early stages of a drop jump task. Differences in contact time initiation were present; however, they are not significant enough to cause neuromuscular differences in the plantar flexor muscles.

Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom

Address correspondence to Dr. Nick Ball,

© 2009 National Strength and Conditioning Association