The Effectiveness of Stretching to Improve Posterior Shoulder Tightness in Overhead Athletes

Mine K, Nakayama T, Milanese S, Grimmer K. Effectiveness of stretching on posterior shoulder tightness and glenohumeral internal-rotation deficit: A systematic review of randomized controlled trials. J Sport Rehabil. 2017;26:294-305.

Background

Repetitive tensile stress to the posterior structures of the shoulder in the follow-through phase of throwing is believed to lead to inflammation, scar formation, and tightness in posterior tissues.  These resultant changes have been termed posterior shoulder tightness (PST) and glenohumeral internal rotation deficit (GIRD).  Both PST and GIRD have been linked to shoulder pain in the athletic and general population.

Purpose

The purpose of this study was to synthesize all available English- and Japanese-language randomized clinical trials reporting on the effectiveness of stretching interventions for PST and GIRD.

Research Methods

Studies with symptomatic or asymptomatic research participants were included in the systematic review.  Eligible studies reported passive shoulder horizontal adduction ROM or IR ROM at 90° abduction or flexion as outcome measures.  Databases were searched from inception through December 2015.    Risk of bias in included studies was assessed using the PEDro scale. The quality of each study was classified as ‘high’ (7/10 or more), ‘moderate’ (5 or 6/10), or ‘low’ (4/10 or less) according to the total PEDro scores.  Two independent reviewers scored each study and a third reviewer was used to mediate disagreements.

Ten studies (8 written in English, 2 written in Japanese) satisfied inclusion criteria and were included in this review.  The total sample size for the review was 553 research participants.  Most participants were asymptomatic.  Six studies recruited various overhead athletes.   The definitions of GIRD or PST were slightly different among studies. Four studies defined GIRD or PST as more than a 10° decrease in IR at 90° abduction in the dominant side compared with the nondominant side.  The other 2 studies outlined GIRD as more than an 18° decrease or more than a 20° decrease in ROM.

Key Results

  • Overall there was a median PEDro score of 6.5/10. Five studies were judged high quality, 3 studies were categorized as moderate quality, and the other 2 studies were low quality.
  • Moderate evidence from 5 low- to high-quality studies show immediate and short-term effects of active, passive and muscle energy (MET) forms of the cross-body stretch on PST and GIRD in asymptomatic individuals.
  • Moderate evidence from 1 high-quality study suggests joint mobilization is not effective when added to the cross-body stretch to improve GIRD in the short term.
  • Moderate evidence from 1 high-quality study suggests the sleeper stretch might not be as effective as the cross-body stretch to improve PST and GIRD in the short term.
  • Moderate evidence from 2 high-quality studies suggests the sleeper stretch is not more effective than all-fours posterior stretching or no intervention to improve PST and GIRD in the short term.

Study Limitations

  • Most studies investigated young asymptomatic research participants
  • Half of the included studies failed to perform an intention-to-treat analysis. This may have overestimated some treatment effects.
  • Small sample sizes of the included studies resulted in many non-significant differences.
  • Three studies specifically investigated baseball players. The results from these studies may not be generalizable to other populations.
  • These findings may be subject to publication bias because trials with positive findings tend to be published more often compared with trials with negative findings.
  • Heterogeneity of included studies prevented pooling the data and objectively summarizing the important findings.

Practical Implications & Additional Thoughts

The primary finding from this study suggests variations of the cross-body stretch are effective for improving PST and GIRD in the short and intermediate term in asymptomatic young athletes.  Conversely, this review did not support the use of the sleeper stretch as an effective intervention to improve PST and GIRD.   Further research is needed to investigate the long-term effects of the cross-body stretch in symptomatic baseball players.

It is possible that additional treatment techniques, such as soft tissue mobilization, would expediate the recovery of ROM in a symptomatic population.   Clinically, I find the combination of soft tissue mobilization to the posterior shoulder and cross-body MET’s to be most effective in the short-term.  Large within session improvements of 10°-20° can be achieved with minimal time investment.  Long-term sustained improvements require regular self-stretching during the competitive season and off-season in youth baseball players.

A lingering question relates to the clinical relevance of PST and GIRD in youth baseball players.   Does PST and GIRD contribute to musculoskeletal injury in this population? Hibberd et al.1 found the age-related increase in GIRD is primarily attributed to humeral retrotorsion rather than soft tissue tightness.  Therefore, these changes may be a necessary adaptation in overhead athletes as they mature.  Keller et al.2 was unable to show a statistically significant association between shoulder ROM deficits in overhead athletes.  However, there was a trend for an association between GIRD and shoulder or elbow injury in overhead athletes across all ages.

Addressing any relevant impairment found during examination should be considered with some form of intervention.  However, it is very likely that any association between GIRD and upper extremity injury is small.  The cross-body stretch is a practical method to address this impairment in overhead athletes.  However, no single stretching exercise should be used as a standalone intervention whether it be directed towards performance enhancement or rehabilitation.

References

  1. Hibberd EE, Oyama S, Myers JB. Increase in humeral retrotorsion accounts for age-related increase in glenohumeral internal rotation deficit in youth and adolescent baseball players. Am J Sports Med. 2014;42(4):851-858. doi:10.1177/0363546513519325.
  2. Keller RA, De Giacomo AF, Neumann JA, Limpisvasti O, Tibone JE. Glenohumeral internal rotation deficit and risk of upper extremity injury in overhead athletes: A meta-analysis and systematic review. Sport Heal A Multidiscip Approach. 2018;Online:1-8. doi:10.1177/1941738118756577.

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