RESUMEN
INTRODUCTION: To evaluate the acute effect of scapular mobilization with associated myofascial release compared to scapular mobilization without myofascial release on butterfly stroke sports performance. DESIGN: Randomized clinical trial. METHOD: Pilot study that non-probabilistically convenience sampling that selected butterfly swimmers who were simply randomized into three groups to receive the standard protocol (scapular mobilization with release of the subscapularis muscle by the lateral edge of the scapula and rib cage detachment) in intervention group (IG), sham group (SG) (scapular mobilization without subscapularis muscle release and without rib cage detachment) or no intervention in control group (CG). We evaluated the stroke frequency, length, and average speed of 30 swimmers using the 8.15 Kinovea® motion analysis system. RESULTS: The findings showed that, compared to the CG and IG, the SG showed a significant reduction in mean velocity (p = 0.002; p = 0.02, respectively), stroke frequency (p = 0.002; p = 0.003, respectively), and stroke length (p = 0.01; p = 0.05, respectively). DISCUSSION: The results showed that manual therapy through scapular mobilization without associated myofascial release with detachment of the scapula from the rib cage worsened the swimming efficiency indicators even after 30 min of application of the technique. The limitations of the studies are related to the sample size, the risk of non-probabilistic contraction bias and the lack of blinding of the evaluators. Thus, the results of this study should be evaluated with caution.