A Comparison of Range of Motion of Joints and Isometric Strength of Lower Extremity Muscles in Female Athletes with and without Dynamic Knee Valgus

The aim of this study was to compare isometric strength and range of motion (ROM) of lower extremity in female athletes with and without dynamic knee valgus. 48 healthy female athletes (age range 15-18 years) in two groups: those with dynamic knee valgus during squat movement that was corrected by a heel lift (n=24) and those with no dynamic knee valgus (n=24 as the control group) with no injury in the past participated in this study. Maximum isometric strength was measured in kilograms using a hand-held dynamometer and active ROM was measured in degrees with a standard plastic goniometer. Independent t test and MANOVA were used to analyze data (P≤0.05). The results showed that the group with dynamic knee valgus had significantly lower mean ankle dorsiflexion ROM (with right knee) (F1.46=5.503, P=0.023) and isometric strength of ankle plantar flexion (F1.46=4.187, P=0.046) than the control group. No other significant differences were observed between the groups. The subjects with dynamic knee valgus exhibited tight and weak lateral and medial gastrocnemius muscles. This result indicated that decreased ankle dorsiflexion ROM as a factor affecting the alteration of movement pattern of lower extremity and consequently a risk factor for knee injuries must receive the attention of clinicians and trainers.