Background: Due to the repetitive rotational and distractive forces exerted onto the posterior shoulder during the deceleration phase of the overhead throwing motion, limited glenohumeral (GH) range of motion (ROM) is a common trait found among baseball players, making them prone to a wide variety of shoulder injuries. Although utilization of instrument-assisted soft tissue mobilization (IASTM), such as the Graston® Technique, has proven effective for various injuries and disorders, there is currently no empirical data regarding the effectiveness of this treatment on posterior shoulder tightness.
Purpose: To determine the effectiveness of IASTM in improving acute passive GH horizontal adduction and internal rotation ROM in collegiate baseball players.
Methods: Thirty-five asymptomatic collegiate baseball players were randomly assigned to one of two groups. Seventeen participants received one application of IASTM to the posterior shoulder in between pretest and posttest measurements of passive GH horizontal adduction and internal rotation ROM. The remaining 18 participants did not receive a treatment intervention between tests, serving as the controls. Data were analyzed using separate 2× 2 mixed-model analysis of variance, with treatment group as the between-subjects variable and time as the within-subjects variable.
Results: A significant group-by-time interaction was present for GH horizontal adduction ROM with the IASTM group showing greater improvements in ROM (11.1°) compared to the control group (-0.12°) (p <0.001). A significant group-by-time interaction was also present for GH internal rotation ROM with the IASTM group having greater improvements (4.8°) compared to the control group (-0.14°) (p < 0.001).
Conclusions: The results of this study indicate that an application of IASTM to the posterior shoulder provides acute improvements in both GH horizontal adduction ROM and internal rotation ROM among baseball players.
Level of evidence: 2b.
Keywords: Manual therapy; rehabilitation; shoulder; throwing athlete.