Purpose:
Anterior cruciate ligament (ACL) injury is one of the most common sports injuries among female athletes, often accompanied by functional and kinematic deficits post-surgery. This study aimed to investigate the effect of an eight-week hopping exercise program on functional (static balance, dynamic balance, knee proprioception) and kinematic (knee valgus angle) indices in female athletes with a history of ACL reconstruction using hamstring autograft.
Methods:
The present study was a semi-experimental study with a pre-test-post-test design. The statistical population of the present study consisted of 26 female athlete (18-30 years old) with a history of ACL surgery, and from them, 20 were selected as the statistical sample and were randomly divided into two experimental groups (n = 10) and control (n = 10). The experimental group underwent a progressive hopping program (three 30-minute sessions per week) in eight weeks, while the control group continued standard rehabilitation. Assessments included static balance (Overall Stability Index via Biodex), dynamic balance (Y-Balance Test), knee proprioception (45° flexion error via Angle Meter 360), and knee kinematics (Frontal Plane Projection Angle [FPPA] via Kinovea during single-leg landing). Normality was assessed using the Shapiro-Wilk test, and homogeneity of variance was evaluated with Levene’s test (p > 0.05). A 2×2 mixed ANOVA (group × time) and Bonferroni post-hoc tests for pairwise comparisons were conducted using SPSS version 27 (p < 0.05).
Results:
In the pre-test, no significant differences were observed between groups in the dependent variables (p > 0.05). The experimental group showed significant improvements: a 35.61% reduction in OSI (ηp² = 0.71), a 44.67% reduction in proprioceptive error (ηp² = 0.86), a 48.62% reduction in FPPA (ηp² = 0.73), and increases of 15.92% in anterior balance, 11.26% in posteromedial balance, 15.18% in posterolateral balance, and 14.08% in overall balance (ηp² = 0.65–0.83). Bonferroni tests confirmed significant differences between groups in the post-test (p < 0.001 for all variables) and significant pre-test to post-test improvements in the experimental group (p < 0.001). The control group showed no significant changes (p > 0.05).
Conclusion:
Hopping exercises effectively improve functional and kinematic deficits in female athletes post-ACL reconstruction and can be integrated into female-specific rehabilitation programs. It is recommended that rehabilitation specialists incorporate this protocol into return-to-sport programs for women with a history of ACL surgery.