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Phys Ther Sport. 2011 Aug;12(3):127-32. doi: 10.1016/j.ptsp.2010.10.001. Epub 2010 Nov 26.

Quadricep and hamstring activation during drop jumps with changes in drop height.

Author information

1
Department of Physical Education, Chinese Culture University, Taipei, Taiwan.

Abstract

OBJECTIVE:

Compare the muscle activation patterns of the quadricep-hamstring during drop jumps with increasing demands of drop heights.

DESIGN:

Observational.

SETTING:

University biomechanics laboratory.

PARTICIPANTS:

Fifteen male and eight female college physical education students.

MAIN OUTCOME MEASURES:

Electromyographic activity of the rectus femoris (RF) and biceps femoris (BF) during the landing and takeoff phase of drop jumps from 20 to 60-cm heights. The ground contact time, vertical ground reaction force (vGRF), knee flexion angle during ground contact, and jump height after takeoff were also analyzed.

RESULTS:

The activation of RF was higher in the drop jump from 60-cm than that from 20- and 30-cm (comparing 107.0 ± 45.9 to 82.3 ± 30.8 and 88.9 ± 38.9 %MVIC, P<.05) during the landing phase. Activation of BF remained similar across all drop heights. Drop jump from 60-cm resulted in greater contact time during takeoff phase and peak vGRF, and resulted in greater maximum knee flexion but straighter knee at ground contact than from lower drop heights.

CONCLUSION:

At drop height of 60-cm, the altered knee muscular activation and movement patterns may diminish the effectiveness of plyometric training and increase the potential injury risk of knee.

PMID:
21802039
DOI:
10.1016/j.ptsp.2010.10.001
[Indexed for MEDLINE]

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