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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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MUSCLE STRENGTH AND QUALITATIVE JUMP-LANDING DIFFERENCES IN MALE AND FEMALE MILITARY CADETS: THE JUMP-ACL STUDY |
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Anthony I. Beutler1  ,
Sarah J. de la Motte1, Stephen W. Marshall2, Darin
A. Padua2 and Barry P. Boden3 |
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1Uniformed Services University of the Health Sciences, Bethesda, MD, 2The University of North Carolina at Chapel Hill, Chapel Hill, NC, 3The Orthopaedic Center, Rockville, MD, USA. |
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© Journal of Sports Science and Medicine (2009) 8, 663 - 671 |
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| ABSTRACT | |||
| Recent studies have focused on gender differences in movement
patterns as risk factors for ACL injury. Understanding intrinsic and extrinsic
factors which contribute to movement patterns is critical to ACL injury
prevention efforts. Isometric lower- extremity muscular strength, anthropometrics,
and jump-landing technique were analyzed for 2,753 cadets (1,046 female,
1,707 male) from the U.S. Air Force, Military and Naval Academies. Jump-
landings were evaluated using the Landing Error Scoring System (LESS), a
valid qualitative movement screening tool. We hypothesized that distinct
anthropometric factors (Q-angle, navicular drop, bodyweight) and muscle
strength would predict poor jump-landing technique in males versus females,
and that female cadets would have higher scores (more errors) on a qualitative
movement screen (LESS) than males. Mean LESS scores were significantly higher
in female (5.34 ± 1.51) versus male (4.65 ± 1.69) cadets (p < 0.001).
Qualitative movement scores were analyzed using factor analyses, yielding
five factors, or "patterns", contributing to poor landing technique.
Females were significantly more likely to have poor technique due to landing
with less hip and knee flexion at initial contact (p < 0.001), more knee
valgus with wider landing stance (p < 0. 001), and less flexion displacement
over the entire landing (p < 0.001). Males were more likely to have poor
technique due to landing toe-out (p < 0.001), with heels first, and with
an asymmetric foot landing (p < 0.001). Many of the identified factor
patterns have been previously proposed to contribute to ACL injury risk.
However, univariate and multivariate analyses of muscular strength and anthropometric
factors did not strongly predict LESS scores for either gender, suggesting
that changing an athlete's alignment, BMI, or muscle strength may not directly
improve his or her movement patterns.
Key words: Jump-landing, ACL injury risk, motor patterns, qualitative movement screen. |
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