Isolation of infraspinatus in clinical test positions.
In recent literature, the infraspinatus muscle is hypothesized to be an important factor preventing cranial migration of the humeral head and enforcing the concavity compression mechanism. However, the relationship between supraspinatus and infraspinatus muscle function is not yet fully understood. On top of that, recent findings point out that the infraspinatus is comprised of two parts – an oblique and a transverse part. As a result, clinical tests aiming to isolate infraspinatus muscle remain inaccurate.
This study sought to determine the testing position in which the infraspinatus activity was most distinct. Results indicate specific activation patterns of both parts of the infraspinatus, the oblique part being most active in all positions. Furthermore, both infraspinatus’ parts were more active than the supraspinatus in the neutral (i.e. 0 degrees of glenohumeral abduction and flexion) and 90 degrees of flexion testing position, suggesting these as best able to distinguish between the supraspinatus and infraspinatus > From Hughes et al., J Sci Med Sport (2013) (Epub ahead of print). All rights reserved to Elsevier Ltd.
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