Hip Muscle Strength, Bilateral Ratios, Antagonistic Ratios and Single Leg Squat Performance in Persons with Low Back Pain and Controls

Document Type

Article

Publication Date

6-1-2012

Publication Title

Medicine & Science in Sports & Exercise

ISSN

1530-0315

Abstract

Many persons suffer from lower back pain (LBP), but causes are not fully understood. Few studies have examined the hip musculature strength differences in persons with LBP history and

whether it contributes to movement deviations during the single leg squat.

PURPOSE: To compare isometric strength, antagonistic ratios, bilateral ratios of the hip muscles and qualitative single leg squat performance between healthy and persons with a history of LBP.

METHODS: Fifteen men with (1.78±.08m, 80.7±15.6kg, 21.9±3.9yrs, Oswestry Disabilty Questionnaire score= 29.1±22.8 ) and without (1.78±.05m, 72.7±11.8kg, 20.2±2.5yrs) LBP history completed isometric strength evaluation of the hip flexor, extensor , adductor (HAd), abductor (HAb), internal rotator and external rotator using hand held dynamometry. Strength assessment order was randomly determined for each subject. Average strength values across three trials were computed and normalized to body mass. Antagonistic and bilateral strength ratios were computed. Furthermore, participants completed the National Academy of Sports Medicine (NASM) single leg squat assessment (SLSA), however only errors associated with hip musculature imbalance were considered for analysis. A pilot reliability study for the strength assessments yielded intraclass correlational coefficients (3, k) between .91 to .98. Three factor analyses of variance (ANOVA) were conducted for the strength values (group by limb by muscle action) and antagonistic ratios (group by limb by ratio). Two factor ANOVA were conducted for the bilateral ratios (group by muscle action). Chi square analyses were used to compare errors during the SLSA.

RESULTS: No significant (P>.05) isolated strength or bilateral ratios differences between the groups existed. Post hoc analysis of a significant group by antagonist ratio interaction (P=.009) for HAb:HAd revealed the LBP group to have a 19% lower ratio than the control group (P=.007). There were no significant SLSA error differences between the groups.

CONCLUSIONS: Although the isometric strength and bilateral ratios did not differ between the LBP and control groups, the LBP demonstrated significantly smaller HAb:HAd ratios than the controls. This study also shows that the NASM SLSA did not detect HAb:HAd differences between LBP sufferers and non-LBP sufferer.

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Copyright © 2012 by the American College of Sports Medicine

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