Vertical jump asymmetries from 6 to 9 months following anterior cruciate ligament reconstruction with hamstring tendon autograft in non‐elite athletes

PURPOSE: To investigate how bilateral vertical jump performance and kinetic asymmetries change from 6 to 9-12 months following anterior cruciate ligament reconstruction (ACLR). METHODS: Ninety-one non-elite athletes who underwent ACLR via hamstring tendon autograft performed bilateral countermovement jumps (CMJs) and drop jumps (DJs) on dual force plates at 6 and 9-12 months post-surgery. Performance outcomes and kinetic variables, including asymmetry indices (AIs), were analysed using mixed models to investigate changes between the two time points. RESULTS: Jump height and reactive strength for both the CMJ and DJ improved between the two time points (p ≤ 0.001). Concentric impulse of the CMJ was the only variable to show a significant between-limb change over time (p ≤ 0.05), which was mainly due to a reduction in the nonoperative limb while the operated limb remained unchanged for both. No significant between-limb changes over time for any DJ variables (p > 0.05). AIs for concentric and eccentric impulse, for both the CMJ and DJ, reduced over time (p ≤ 0.05), except for peak landing force in the CMJ. CONCLUSIONS: Non-elite athletes after ACLR demonstrated improvements in jump height and reactive strength from 6 to 9-12 months post-surgery, while improvements in eccentric and concentric between-limb asymmetries for both the CMJ and DJ were primarily due to a reduction in the nonoperated limb. LEVEL OF EVIDENCE: Level IV.