I have played the game of baseball for 15 years and I have seen a lot of pitchers that have issues with the shoulder. Not many players pay attention to the fact that baseball is an incredibly unilateral sport and there is too much pitching volume in practice.
Baseball players are prone to a number of shoulder injuries due to repeated overload placed on the posterior shoulder structures as well as the potential for having tightness of these structures. Frequent occurrences of injury and associated posterior shoulder tightness are experienced as decreased glenohumeral (GH) horizontal adduction and internal rotation range of motion in the throwing shoulder of baseball players. Researchers have examined the effects of various stretching techniques for improving GH horizontal adduction ROM and internal rotation ROM. These stretching techniques have resulted in different outcomes adding to the confusion corrective techniques for improving GH ROM. There has been no research that has examined the effectiveness of instrument assisted soft tissue mobilization (IASTM) for treating these restrictions.
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 (Lauder 2014). Although using instrument‐assisted soft tissue mobilization (IASTM), such as the Graston Technique, has proven effective for a number of injuries and disorders, there is currently no useful data regarding the effectiveness of this treatment on posterior shoulder tightness.
Lauder (2014) determined the effectiveness of IASTM in improving acute passive GH horizontal adduction and internal rotation ROM in collegiate baseball players. 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. 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°). 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°). 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.
Past researchers have consistently found that overhead throwing athletes undergo structural and mechanical changes in the GH joint. This result in alterations in ROM and are commonly associated with various shoulder pathologies (Lauder 2014). Unfortunately, problems remain regarding the clinical effectiveness of the various techniques that have been investigated for treating posterior shoulder tightness. The results are the first to demonstrate that a brief application of an instrument assisted soft tissue mobilization applied to the posterior shoulder region results in immediate improvements in GH horizontal adduction ROM and internal rotation ROM among baseball players.
Sports Assessments at COR focuses on a detailed sporting biomechanics and movement skill analysis. This combination provides critical information for enhancing sport, resolving pain, or preventing injuries in the sport. Unlike other assessments, COR breaks down the individual sport, not just irrelevant tasks, as improving the sport is the main goal.
Reference:

1. Laudner K, Compton BD, McLoda TA, Walters CM. Acute effects of instrument assisted soft tissue mobilization for improving posterior shoulder range of motion in collegiate baseball players. Int J Sports Phys Ther. 2014 Feb;9(1):1-7.

Written by Chris Barber, CPT