Effect of Instrument-Assisted Soft Tissue Mobilisation vs. Posterolateral MWM on Range of Motion in Overhead Athletes With Posterior Shoulder Tightness: A Randomised Clinical Trial

INTRODUCTION

The shoulder complex accounts for 30% of all injuries sustained by overhead and throwing athletes, making it the most frequently injured body area.^[1] Among the numerous shoulder-related issues, posterior shoulder tightness (PST) and glenohumeral internal-rotation deficit (GIRD) are particularly seen in athletes involved in overhead sports like baseball, tennis, swimming, and cricket.^[2]

PST refers to “a limitation of the extensibility within the posterior soft tissue of the shoulder, including both contractile and non-contractile elements, as well as osseous changes in the form of humeral torsion, which develops through training adaptations in overhead athletes”.^[3] It is commonly associated with GIRD, shoulder impingement, rotator cuff injuries, and labral tears, making its assessment and management essential in both clinical and sports settings.^[4] The repetitive tensile load placed on the glenohumeral joint during overhead activities predisposes athletes to PST. While it is observed in both athletic and non-athletic populations, its incidence is notably higher among overhead athletes due to the nature of their sport.^[5,6] Ichinose et al. reported a prevalence of PST of 20.2% among baseball players, with affected individuals demonstrating a significant reduction in internal rotation range of motion (ROM) in the dominant shoulder compared to those who did not have PST.^[7]

Clinically, PST is characterised by restricted glenohumeral internal rotation, horizontal adduction, and low flexion. Hall et al. proposed that PST can be diagnosed using three clinical measures: a side-to-side discrepancy of 10° or more in two of the three aforementioned movements, or a difference of at least 20° in a single test.^[8] Overhead throwing athletes demonstrate distinct mobility adaptations, including increased external rotation and decreased internal rotation. Such adaptations are attributable to osseous changes, including humeral retroversion, and soft tissue changes, such as capsuloligamentous and muscular tightness, resulting from repetitive overhead activities.^[9,10]

There are various physiotherapy treatments that have been investigated for targeting PST. Soft tissue therapy techniques like myofascial release, instrument-assisted soft tissue mobilisation (IASTM), and active release technique have proven effective in enhancing ROM and reducing pain. Recent studies suggest that IASTM may outperform self-stretching in improving internal rotation and horizontal adduction in overhead athletes.^[11] These methods help decrease rotator cuff stiffness, increase motion range, elevate pain tolerance during activity, and may reduce hyperactivity in overactive muscles, fostering better intermuscular coordination.^[12]

Mobilisation with movement (MWM) is a manual therapy intervention where the therapist applies a sustained glide to a stiff or painful joint while the patient performs an active movement in order to restore joint mobility and reduce discomfort.^[13] Specifically, posterior gliding mobilisation targets normalising glenohumeral mechanics by ensuring appropriate humeral head translation.^[14] Moreover, posterolateral mobilisation has been effective in other shoulder conditions like adhesive capsulitis, with significant improvements in ROM and reductions in pain and functional disability.^[15]

While both MWM and IASTM are commonly employed to address shoulder mobility deficits, the specific mechanisms of their action fundamentally differ: MWM primarily targets sustained capsular stretching and joint mobility, whereas IASTM focuses on localised myofascial modulation and neurophysiological changes. Existing literature often supports the individual efficacy of these techniques but lacks rigorous comparative studies that directly contrast the sustained gains achieved through these two distinct physiological approaches. However, despite the demonstrated efficacy of both IASTM and mobilisation techniques in managing PST, there is a dearth in the literature addressing the application of Mulligan mobilisation specifically for PST. Furthermore, no studies have directly compared the effects of IASTM and posterolateral MWM in overhead athletes with PST. Therefore, the current study aimed to examine the effects of IASTM and posterolateral MWM on shoulder ROM and mobility in overhead athletes with PST. We hypothesised that IASTM and posterolateral MWM would demonstrate a difference in their effect on shoulder ROM and mobility in overhead athletes with PST.

MATERIAL AND METHODS

GROUP A: Posterolateral MWM + Conventional treatment

The patient was positioned standing, facing a wall with both hands placed against it for support. The therapist stands posterolateral to the patient and placed one hand over the scapula to stabilise it, while the other hand was positioned anteriorly on the belt secured over the head of the humerus. The belt was placed along the anteromedial aspect of the affected glenohumeral joint. Once positioned, the therapist applied a controlled pull through the belt to produce a gentle, prolonged posterior-lateral inferior glide of the humeral head [Figure 1]. The patient was instructed to bend forward from the pelvis, bringing her hips backward.^[22] The volume of intervention consisted of 3 sets of 10 repetitions of MWM with an interval of 60 sec rest between sets.^[23]

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Figure 1:

Posterolateral mobilisation with movement in the standing position.

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GROUP B: IASTM + Conventional treatment

Participants were lying prone, with their dominant throwing arm positioned in neutral rotation. To make sure the participant’s humerus stays at the same level as the acromion process, a towel was placed underneath it.^[24] Before the treatment, vaseline was applied to the skin as a lubricant, and the M2T blade was cleaned using an alcohol pad before application. It was then positioned at a 45° angle and used to deliver slow, controlled strokes along the muscle fibres, from origin to insertion, for ∼3 min.^[25] The strokes were delivered in both perpendicular and parallel directions relative to the muscle fibres along the posterior axillary border, targeting the posterior deltoid, latissimus dorsi, teres major and minor, and infraspinatus muscles [Figure 2].^[24] Following the treatment, participants experiencing hyperemia or a burning sensation were advised to use an ice pack on the affected area.^[26]

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Figure 2:

Instrument-assisted soft tissue technique over the posterior axillary border muscle fibres.

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RESULTS

The flow of participants throughout the study, from initial screening to final analysis, is detailed in the Consolidated Standards of Reporting Trials (CONSORT) flow diagram [Figure 3]. A total of 73 individuals were assessed for eligibility, and 52 overhead athletes (Group A: n = 26, Group B: n = 26) completed the study with no dropouts. The baseline demographic and clinical characteristics of the two groups are presented in Table 1 (age, BMI, total years in sport) and Table 2 (gender and time). Independent t-test and Chi-square analysis were performed for comparison. No statistically significant differences (p > 0.05) were found between Group A and Group B, which confirmed that the randomisation process successfully created two homogenous groups. Both intervention groups demonstrated statistically significant within-group improvements in horizontal adduction, internal rotation, external rotation, and AST from pre-intervention to post-intervention and at 1-week follow-up (Friedman’s ANOVA, p < 0.0001). For horizontal adduction and external rotation, both groups showed significant improvements over time, with no significant between-group differences (p > 0.05), indicating similar effectiveness for these outcomes. Group A exhibited significantly greater improvements in internal rotation compared to Group B, both immediately post-intervention (mean change: 13.86° vs. 8.05°, p = 0.0001) and at 1-week follow-up (13.28° vs. 8.93°, p = 0.0001) [Table 3]. PST, measured as the side-to-side difference in internal rotation, both groups showed significant within-group reductions (p <0.0001). However, Group A achieved significantly greater reductions than Group B at both post-test (p = 0.0002) and at 1-week follow-up (p = 0.0001) [Table 4 and Figure 4]. Conversely, Group B demonstrated a significantly greater immediate improvement in AST scores (p = 0.0206), although the effect was not sustained at 1 week (p = 0.0659), suggesting a more transient functional gain [Table 5]. These findings indicate that while both interventions were effective, Group A (posterolateral MWM and cross-body stretch) demonstrated superior outcomes in internal rotation and PST reduction. Moreover, Group A was more effective in maintaining these gains over time, suggesting greater long-term benefit in addressing PST in overhead athletes.

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Figure 3:

CONSORT chart of the study. CONSORT: Consolidated Standards of Reporting Trials.

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Figure 4:

Comparison of Group A and Group B with posterior shoulder tightness (PST in degrees) at different treatment time points. PST: Posterior shoulder tightness.

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DISCUSSION

This research assessed and compared the efficacy of IASTM and posterolateral MWM, each combined with a cross-body stretch, on shoulder ROM and alleviating PST among overhead athletes. The findings demonstrated that both interventions produced significant improvements in shoulder ROM and mobility. However, posterolateral MWM resulted in significantly greater and more sustained improvements in glenohumeral internal rotation and reduction in PST at the one-week follow-up.

The cross-body stretch was incorporated in both groups due to its documented efficacy in addressing posterior shoulder soft tissue restrictions. Evidence from systematic and scoping reviews has identified this stretch as an effective intervention for improving internal rotation and horizontal adduction in individuals with PST, particularly in overhead athletes.^[5,27] The significant improvements observed within both groups may therefore be partially attributed to increased posterior soft tissue extensibility achieved through this intervention.

Participants receiving IASTM demonstrated significant immediate improvements in shoulder mobility, particularly as reflected by the AST. These findings are consistent with previous reports describing acute increases in shoulder ROM following IASTM application to the posterior shoulder musculature.^[24,28] The observed effects are likely attributable to myofascial modulation, involving transient reductions in tissue stiffness and neuromuscular tone mediated through mechanoreceptor stimulation.^[11,12] It exerts controlled microtrauma to soft tissues, promoting fibroblast proliferation, realignment of collagen fibres, and resorption of scar tissue. These effects may explain the immediate ROM improvement observed post-treatment.^[5] However, the effects were not sustained at one-week follow-up, suggesting that these effects may be predominantly neurophysiological and short-term, requiring repeated or adjunctive interventions for long-term retention. This is supported by Gohil et al., who found IASTM improved internal rotation and horizontal adduction in athletes with GIRD, but noted continued sessions were necessary for lasting outcomes.^[28]

In contrast, Group A, which underwent posterolateral MWM, showed immediate improvements in internal rotation and PST, along with better maintenance of these improvements at the 1-week follow-up. These outcomes may be attributed to the combined biomechanical and neurophysiological mechanisms of MWM. Posterolateral gliding mobilisation facilitates posterior-inferior translation of the humeral head, thereby restoring normal joint arthrokinematics often limited in individuals with PST due to capsular or muscular tightness. Previous studies have demonstrated that end-range mobilisation techniques result in an immediate increase in internal rotation through mechanical capsular stretch, along with physiological responses such as increased local circulation and sympathetic nervous system responses, which may contribute to improved tissue extensibility.^[4] These findings are also consistent with a recent randomised controlled trial by Wang et al., which demonstrated that three sets of MWM significantly improved shoulder abduction ROM by enhancing joint mechanics and tissue extensibility, confirming its role in optimising shoulder mobility.^[29]

The differential response observed in the AST further highlights the contrast between the interventions. While IASTM produced greater immediate improvements in functional reach, these changes were not retained at follow-up. This may reflect short-term neuromuscular inhibition or reciprocal inhibition effects without substantial structural adaptation.^[7] In contrast, the more stable improvements observed following MWM indicate that interventions targeting joint mechanics and capsular structures may be more effective in achieving sustained functional gains in athletes with PST.

From a clinical standpoint, both interventions appear beneficial when applied to appropriate therapeutic goals. IASTM may be considered for short-term improvements in shoulder mobility, particularly during early rehabilitation or pre-training preparation. Posterolateral MWM, however, appears more effective for addressing capsular contributors to PST and achieving sustained improvements in internal rotation. Based on available evidence, these interventions are commonly applied at a frequency of two to three sessions per week over a period of 3-4 weeks in athletic populations.^[5,11] Integration of joint mobilisation techniques with stretching and progressive exercise may optimise outcomes in overhead athletes.

Overall, PST represents a clinically relevant impairment associated with altered shoulder mechanics and increased injury risk in overhead athletes.^[1] The findings of the present study support the use of posterolateral MWM as a preferred intervention for sustained reduction of PST, while acknowledging the role of IASTM as an adjunct for improving short-term shoulder mobility.

CONCLUSION

Both intervention protocols were found to be effective in enhancing shoulder mobility and internal rotation ROM in overhead athletes with PST. Specifically, the posterolateral MWM intervention, along with cross-body stretch, appeared to be more effective in achieving superior gains and retention in PST reduction, while the IASTM intervention demonstrated a significantly greater immediate improvement in overall shoulder mobility. For clinicians managing overhead athletes with PST, these findings suggest prioritising posterolateral MWM when the primary clinical goal is to achieve maximal and lasting reduction in PST (i.e., increasing IR ROM), and utilising IASTM effectively when the immediate objective is to quickly restore general shoulder mobility before functional training. However, caution is warranted when interpreting the immediate, significant gains observed with IASTM, as the study only assessed the short-term effects of a single treatment session. Future research, therefore, should investigate the long-term effects of multiple structured sessions of both MWM and IASTM to confirm sustained efficacy, and further studies are needed to examine the combined application of these techniques and to correlate the observed treatment effects with sport-specific functional outcomes.