Patterns of muscle coordination during dynamic glenohumeral joint elevation: An EMG study

Hawkes, David H, Khaiyat, Omid A, Howard, Anthony J, Kemp, Graham J ORCID: 0000-0002-8324-9666 and Frostick, Simon P (2019) Patterns of muscle coordination during dynamic glenohumeral joint elevation: An EMG study. PLOS ONE, 14 (2). e0211800-.

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Abstract

The shoulder relies heavily on coordinated muscle activity for normal function owing to its limited osseous constraint. However, previous studies have failed to examine the sophisticated interrelationship between all muscles. It is essential for these normal relationships to be defined as a basis for understanding pathology. Therefore, the primary aim of the study was to investigate shoulder inter-muscular coordination during different planes of shoulder elevation. Twenty healthy subjects were included. Electromyography was recorded from 14 shoulder girdle muscles as subjects performed shoulder flexion, scapula plane elevation, abduction and extension. Cross-correlation was used to examine the coordination between different muscles and muscle groups. Significantly higher coordination existed between the rotator cuff and deltoid muscle groups during the initial (Pearson Correlation Coefficient (PCC) = 0.79) and final (PCC = 0.74) stages of shoulder elevation compared to the mid-range (PCC = 0.34) (p = 0.020-0.035). Coordination between the deltoid and a functional adducting group comprising the latissimus dorsi and teres major was particularly high (PCC = 0.89) during early shoulder elevation. The destabilising force of the deltoid, during the initial stage of shoulder elevation, is balanced by the coordinated activity of the rotator cuff, latissimus dorsi and teres major. Stability requirements are lower during the mid-range of elevation. At the end-range of movement the demand for muscular stability again increases and higher coordination is seen between the deltoid and rotator cuff muscle groups. It is proposed that by appreciating the sophistication of normal shoulder function targeted evidence-based rehabilitation strategies for conditions such as subacromial impingement syndrome or shoulder instability can be developed.

Item Type:	Article
Uncontrolled Keywords:	Rotator Cuff, Shoulder Joint, Humans, Shoulder Impingement Syndrome, Electromyography, Range of Motion, Articular, Movement, Adult, Female, Male, Deltoid Muscle, Superficial Back Muscles
Depositing User:	Symplectic Admin
Date Deposited:	22 Feb 2019 09:03
Last Modified:	19 Jan 2023 01:02
DOI:	10.1371/journal.pone.0211800
Open Access URL:	https://doi.org/10.1371/journal.%20pone.0211800
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3033243