Muscle strength and flexibility characteristics of people displaying excessive medial knee displacement.

OBJECTIVE To determine differences in strength and range of motion (ROM) between participants who exhibit medial knee displacement (MKD) during a squat that is corrected by a heel lift and those who do not. DESIGN Case control. SETTING Sports medicine research laboratory. PARTICIPANTS Thirty-seven healthy subjects (control, 19; MKD, 18) with no lower-extremity injury in the past 6 months volunteered to participate. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Peak force was measured in newtons using a hand-held dynamometer and passive ROM was measured in degrees with a goniometer. Separate multivariate analyses of variance were used to determine differences in strength and ROM between groups. Post hoc testing was used to elucidate differences between groups. RESULTS The MKD group had the following: greater hip external rotation strength (P=.03), increased hip extension strength (P=.01), less plantarflexion strength (P=.007), and increased hip external rotation ROM (P=.008). CONCLUSIONS The MKD group exhibited tight and weak ankle musculature. Interventions focusing on improving strength and ROM of the ankle may improve kinematics during a squat.

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