Date of Award

Fall 2018

Document Type

Thesis Restricted

Degree Name

Master of Science (MS)

Department

Kinesiology

Committee Chairperson

David Stearne, Ph.D.

Committee Member

Kenneth Clark, Ph.D.

Committee Member

Edward Kubachka, M.S.

Abstract

Background: Anterior cruciate ligament (ACL) injuries remain prevalent in team sports involving cutting, jumping and pivoting movements. Closed kinetic chain resistance is considered most effective for ground force attenuation and alignment during landing. However, treadmill-based resistance training for developing hip-specific strength has not been investigated. Our purpose was to examine effect of a novel incline treadmill-based resistance training program on a functional landing task.

Methods: Hip and knee extensor strength ratios, vertical rate of loading (vROL) and reactive strength index (RSI) were measured with a Kistler force plate, and knee and trunk flexion angles measured from motion capture. 15 healthy female intercollegiate lacrosse players (age = 19.5 ± 1.7 years, height = 1.65 ± .23m, weight = 59.33 ± 5.4kg) participated in repeated measures, cross-sectional design with written informed consent. Changes in vROL, RSI and knee and trunk flexion angles during 30cm drop jumps were assessed pre to post training that occurred for six weeks, two sessions per week, with treadmill set at 15 percent grade and progressive cable resistance set initially at 40% of hip extensor strength for seven minutes per session.

Results: Paired samples t-tests showed significant (p = .007) increase in RSI post training, reflecting a 12.5% rise in RSI scores. Hip extensor strength trended toward significance (p= .07), and knee extensor strength significantly increased (p= .001) post training.

Conclusion: RSI changes reflect more fluid transitioning from loading through take off, possibly enhanced by strength gains. Future research should investigate neuromuscular stiffness changes protective against ACL injury.

This study was supported by a research grant from US Lacrosse Center for Sport Science, Sports Science and Safety Committee.

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