Altered lower limb kinematics and muscle activities in soccer players with chronic ankle instability.

OBJECTIVE: To examine the lower limb kinematics and muscle activities in diagonal single-leg rebound jump in soccer players with chronic ankle instability (CAI).

DESIGN: Cross-sectional study.

SETTING: Laboratory.

PARTICIPANTS: Thirty male collegiate soccer players participated: 15 with CAI were compared with 15 without CAI, matched by physical description.

INTERVENTION(S): In the diagonal single-leg rebound jump, participants stood on one leg on a 30-cm high box, hopped down diagonally (45°) onto a force plate, and jumped vertically as high as possible with hands on their hips.

MAIN OUTCOME MEASURES: Hip, knee, and ankle kinematics were acquired using a motion capture system. The activity of the gluteus medius, hip adductor, and lower leg muscles was recorded using electromyography. Jump performance was calculated using a force plate.

RESULTS: The CAI group had (i) decreased hip adduction, knee flexion, external rotation, and dorsiflexion angle; (ii) reduced hip adductor and peroneus muscle activations; and (iii) reduced jump height and short flight time.

CONCLUSIONS: Male collegiate soccer players with CAI showed altered kinematics and muscle activities during a diagonal single-leg rebound jump; this may adversely affect rebound jump performance.