Effectiveness of electromyography biofeedback training on scapular kinematics and muscle activation in patients with scapular dyskinesis: a systematic review and meta-analysis

Background: This study aimed to determine the effectiveness of electromyography (EMG) biofeedback training on scapular kinematics and/or muscle activation in patients with scapular dyskinesis (SD) associated with subacromial impingement syndrome (SIS).Methods: An electronic search was conducted in the Medline, Embase, Scopus, Web of Science, CINAHL, SPORTDiscus, LILACS, CENTRAL, and PEDro databases. Eligibility criteria comprised randomized clinical trials investigating the effects of adding EMG biofeedback training to scapular-focused exercises on scapular kinematics and/or muscle activation in patients with SD associated with SIS. Data were pooled using a Hartung-Knapp-Sidik-Jonkman random-effects method or Mantel–Haenszel fixed-effects model. Certainty of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE).Results: Four trials met the eligibility criteria. The mean difference (MD) for upward rotation was 1.13° (P=0.07), and that for downward rotation was 1.2° (P=0.08). The MDs for muscle activation of the lower trapezius during scapular plane elevation and descending movements were 7.22% (P=0.010) and 2.26% (P<0.001), respectively. The MDs for the muscle balance ratios of the upper/lower trapezius and upper trapezius/serratus anterior were 0.11% (P=0.95) and 0.15% (P=0.04), respectively. All differences favored the EMG biofeedback plus scapular-focused exercises group.Conclusions: In the short-term, adding EMG biofeedback training to scapular-focused exercises resulted in significant differences only in lower trapezius activity. Conversely, the results were inconclusive regarding improvements in scapular kinematics and changes in the activation of other scapular muscles. The quality of evidence ranged from very low to high according to GRADE rating, suggesting that the effect of EMG biofeedback might not be captured in this study.Level of evidence: I.