ORIGINAL ARTICLE

Evaluation of shoulder internal rotator muscle strength in baseball players with physical signs of glenohumeral joint instability

D L Falla, S Hess and C Richardson

Department of Physiotherapy, University of Queensland, Brisbane, Queensland, Australia

Correspondence to:
Correspondence to:
Ms Falla, Department of Physiotherapy, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia;
d.falla{at}shrs.uq.edu.au

Objectives: To identify whether subjects with glenohumeral translational instability present with a strength deficit in their internal rotator musculature, and therefore to determine if general strengthening exercises are warranted for the management of this condition.

Methods: Eighteen male baseball players were allocated to two groups on the basis of expert clinical evaluation of the presence (n = 8) or absence (n = 10) of shoulder translational instability. A strain gauge was used to calculate the force generated during maximal isometric internal rotation contractions in neutral shoulder rotation and 30° of internal rotation.

Results: The Mann-Whitney test identified no significant difference in force production during the maximum contractions in neutral rotation between the two subject groups. In the position of 30° shoulder internal rotation, subjects with glenohumeral translational instability produced significantly greater force than the control group (p<0.05).

Conclusions: High load strength testing cannot be used as a diagnostic tool to identify people with glenohumeral instability. Similarly, heavy resistance strengthening exercises for the internal rotator musculature are not warranted during rehabilitation.

Keywords: glenohumeral joint; rotator muscle strength; shoulder instability

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