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Open Access Highly Accessed Research article

The impact of subacromial impingement syndrome on muscle activity patterns of the shoulder complex: a systematic review of electromyographic studies

Rachel Chester12*, Toby O Smith13, Lee Hooper4 and John Dixon5

Author Affiliations

1 Institute of Health and Social Sciences Research, Faculty of Health, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK

2 Physiotherapy Department, Norfolk and Norwich University Hospital, Norwich, NR4 7UY, UK

3 Institute of Orthopaedics, Norfolk and Norwich University Hospital, Norwich, NR4 7UY, UK

4 Institute of Biomedical and Clinical Sciences, Faculty of Health, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK

5 Health and Social Care Institute, School of Health and Social Care, Teesside University, Middlesbrough, TS1 3BA, UK

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BMC Musculoskeletal Disorders 2010, 11:45  doi:10.1186/1471-2474-11-45

Published: 9 March 2010

Abstract

Background

Subacromial impingement syndrome (SIS) is a commonly reported cause of shoulder pain. The purpose of this study was to systematically review the literature to examine whether a difference in electromyographic (EMG) activity of the shoulder complex exists between people with SIS and healthy controls.

Methods

Medline, CINAHL, AMED, EMBASE, and grey literature databases were searched from their inception to November 2008. Inclusion, data extraction and trial quality were assessed in duplicate.

Results

Nine studies documented in eleven papers, eight comparing EMG intensity and three comparing EMG onset timing, representing 141 people with SIS and 138 controls were included. Between one and five studies investigated each muscle totalling between 20 and 182 participants. The two highest quality studies of five report a significant increase in EMG intensity in upper trapezius during scaption in subjects with SIS. There was evidence from 2 studies of a delayed activation of lower trapezius in patients with SIS. There was otherwise no evidence of a consistent difference in EMG activity between the shoulders of subjects with painful SIS and healthy controls.

Conclusions

A difference may exist in EMG activity within some muscles, in particular upper and lower trapezius, between people with SIS and healthy controls. These muscles may be targets for clinical interventions aiding rehabilitation for people with SIS. These differences should be investigated in a larger, high quality survey and the effects of therapeutically targeting these muscles in a randomised controlled trial.