The Effects of Isolated Hip Abductor and External Rotator Muscle Strengthening on Concentric and Eccentric Strength and Jump-Landing Mechanics using Landing Error Scoring System

Landing has been shown to be one of the most important mechanisms of non-contact ACL injures. The relationship between hip abductor and external rotator muscle strength and landing mechanics has been well documented in the literature. But, a few studies have been investigated the effect of hip strengthening on landing mechanics. So, the purpose of the study was to investigate the effect of isolated hip abductor and external rotator muscle strengthening on concentric and eccentric strength and jump-landing mechanics using landing error scoring system.

Thirty-two males with knee valgus angle more than 8 degrees were randomized into a training (n=16) or control group (n=16). The training group carried out 8 weeks of bilateral hip abductor and external rotator strengthening 3 times per week. Pre and post-test hip strength were measured with an isokinetic dynamometer (Kin-Com) and landing mechanics were assessed by Landing Error Scoring System. Data were analyzed via SPSS software applying paired sample t-test and ANCOVA at a significant level P< 0.05.

Between-group analysis revealed that there were significant group effects for hip strength and landing error score. Subjects in the training group demonstrated significantly greater concentric and eccentric hip abductor (P<0.001, P=0.004) and external rotator peak torques (P=0.01, P<0.001), also they showed a significant decrease in landing error score (P=0.004) respectively, whereas no within-group change was noted in the control group.

An eight-week hip abductor and external rotator strengthening program was effective in improvement concentric and eccentric hip abductor and external rotator strength and landing mechanics. This kind of exercise might decrease less score by improved pelvis position and reduced knee valgus and trunk compensatory movement.