The effects of isokinetic knee extensor and flexor strength on dynamic stability as measured by functional reaching

Abstract

BACKGROUND: Team sport athletes require dynamic stability in unilateral activities for their sports, which necessitates some degree of knee flexion and extension strength. OBJECTIVE: To analyze the possible association of knee extension and flexion strength with dynamic stability, as measured by the Star Excursion Balance Test (SEBT). METHODS: Sixteen male team sport athletes completed the SEBT, which involves a series of unilateral squats with the subject maximally reaching with the other leg in eight directions. Knee muscle strength was measured isokinetically both concentrically (60 ◦ /s, 180 ◦ /s, 240 ◦ /s) and eccentrically (30 ◦ /s). Subjects were divided into better and lesser groups based on mean functional reach distance. A 1-way analysis of variance (p 0.05) determined between-group differences in reach distances and relative torque. RESULTS: Subjects with better dynamic stability generated greater knee extensor torque concentrically at 180 ◦ /s for the right leg, and at all speeds for the left leg. The effects of knee strength were particularly noteworthy for the left leg, as subjects with better dynamic stability reached significantly further across all 8 directions. CONCLUSION: The results indicate that greater knee extensor strength may enhance unilateral dynamic stability in team sport athletes.