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Hip Muscles and Drop Jump Performance
Date Permissions Signed
Date of Award
Department or Program Affiliation
Master of Science (MS)
Health and Human Development
San Juan, Jun G.
Suprak, David N. (Nicholas S.)
Buddhadev, Harsh H., (Harsh Harish)
Washburn, Nick (Nicholas S.)
The anterior cruciate ligament is the most frequently injured ligament in youth ages 8-14 (years) in the United States. This injury is often observed with abnormal valgus knee posture during dynamic landing tasks. Improvement of hip muscle function has positive associations with increasing lower extremity dynamic task competency. Much remains unknown with respect to the merit of integrating hip muscle-specific exercise programs in the aged 8-14 population for improving knee posture during jump landing. Therefore, the purpose of this investigation was to quantify the effects of 6-weeks of hip strengthening exercises on frontal plane knee position in the drop jump test with 7th-grade middle school students. The authors hypothesized that compared to the age-matched control group, the strength training group will show significant changes in frontal plane knee position, specifically a reduction in knee valgus, during drop landings. This intervention study included 57 youth (ages 12-13), who were randomly placed in an experimental or control group. First, to ascertain baseline knee position, all particpants were recorded performing the drop jump test facing a high speed camera. Then, the experimental group performed a series of dynamic warm-up and hip muscle-focused exercises for six weeks, while the control group completed a general warm-up. Post-intervention, pre-test procedures were replicated. A two-way mixed ANOVA was used to measure changes in frontal plane knee position from pre- to post-intervention. Results indicated that the exercise group achieved significantly greater post-intervention improvement in frontal plane knee position on the right knee (p = 0.006), with a mean difference of 7.52° change from valgus to varus posture during landing compared to the control. Further, the exercise group’s left knee significantly differed in post-intervention frontal plane knee position compared to that of the control (p = 0.011), by an average of 6.87°. Overall, with the intervention program the exercise group landed in a less valgus position from pre- to post-test. Six weeks of dynamic warm-up and hip muscle-focused exercises was effective in generating significant changes in frontal plane knee position during the landing phase of a drop jump in male and female 7th-grade middle school students.
Hip muscles, anterior cruciate ligament, knee valgus, kinematics
Western Washington University
Subject – LCSH
Anterior cruciate ligament; Knee--Wounds and injuries; Knee--Muscles; Muscle strength
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Corl-Baietti, Blake, "The Effects of 6 Weeks of Hip-Strengthening Exercises on Drop Jump Performance in Middle School Students" (2020). WWU Graduate School Collection. 958.