Association between electromyographic and neurophysiological indices and functional and function-related outcomes after lower-limb injury: A three-level meta-analysis

BackgroundLower-limb sports injuries may leave persistent neuromuscular deficits that conventional functional measures do not fully capture. Surface electromyography (sEMG) and related neurophysiological indices may provide complementary information, but their associations with functional and function-related outcomes remain uncertain.MethodsFollowing PRISMA guidance (PROSPERO: CRD420261416860), PubMed, Web of Science, Embase, the Cochrane Library, and CNKI were searched from inception to 2 May 2026. Eligible studies reported correlations between EMG/neurophysiological indices and functional or function-related outcomes after lower-limb injury. Methodological quality was assessed using the JBI checklist. A three-level random-effects model pooled Fisher-transformed correlations while accounting for effect sizes nested within studies. Subgroup analyses were considered exploratory because few independent studies were available.ResultsSix studies contributed 14 effect sizes from 135 participants. The pooled association was moderate and positive (Fisher's Z = 0.536, 95% CI 0.305-0.766, p = 0.003; r = 0.490). The 95% prediction interval was 0.201-0.700, although its stability was limited. The largest descriptive estimates occurred for patellofemoral pain and central activation ratio (both r = 0.715), but both were based on the same two studies and four effect sizes, preventing separation of injury-type and index-class effects. Outcome-type differences were not significant (Q = 0.391, p = 0.823). Leave-one-out estimates remained positive (r = 0.419-0.531). Publication bias could not be assessed reliably.ConclusionEMG/neurophysiological indices may be positively associated with functional and function-related outcomes after lower-limb injury. However, the evidence base is small, subgroup findings are exploratory, and larger prospective studies using standardized protocols are needed.