Persistent alterations in muscle activation patterns during landing tasks after anterior cruciate ligament reconstruction in return-to-sport cohorts: A systematic review and meta-analysis of electromyography studies.

PURPOSE: To categorize landing tasks in electromyography (EMG) studies and compare muscle activity during landing between patients with anterior cruciate ligament reconstruction (ACLR) reported as having returned to sport and healthy controls.

METHODS: We systematically searched seven databases (PubMed, Embase, Web of Science, Cochrane Library, Scopus, CINAHL, SPORTDiscus) from inception to 10 December 2025. Studies using EMG to assess muscle activity during landing tasks were included when they compared the reconstructed limb of ACLR patients reported as having returned to sport with limbs from healthy controls. Random-effects meta-analyses evaluated between-group differences using standardized mean differences (SMDs) with 95% confidence intervals (CIs), with findings categorized using an internal evidence classification.

RESULTS: Thirty-two studies were included, comprising 556 individuals with ACLR from return-to-sport cohorts and 501 healthy controls. Thirteen landing tasks were analysed, involving fifteen lower-limb muscles and four EMG outcome measures. Each pooled comparison included 2-5 studies. Three findings were classified as moderate evidence: greater activation of the medial hamstrings during the reactive phase of single-leg drop landing (based on five studies, SMD = 0.35, 95% CI [0.01, 0.69], I2 = 0%), greater gluteus maximus activation during the reactive phase of single-leg drop vertical jump (based on three studies, SMD = 0.63, 95% CI [0.22, 1.03], I2 = 0%) and earlier rectus femoris onset in single-leg hop for distance (based on three studies, SMD = -0.64, 95% CI [-1.13, -0.14], I2 = 19%). Most other findings showed no between-group differences or were classified as limited or very limited evidence.

CONCLUSION: ACLR patients reported as having returned to sport may exhibit task-specific alterations in muscle activation patterns compared with healthy controls, and these alterations may be more readily detected during certain single-leg landing tasks. Further prospective and interventional studies are needed to clarify their clinical relevance.

LEVEL OF EVIDENCE: Level IV.