Normal shoulder muscular activation and co-ordination during a shoulder elevation task based on activities of daily living: An electromyographic study

Authors

  • David H. Hawkes,

    1. Musculoskeletal Science Research Group, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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  • Omid Alizadehkhaiyat,

    1. Musculoskeletal Science Research Group, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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  • Anthony C. Fisher,

    1. Department of Medical Physics and Clinical Engineering, Royal Liverpool University Hospital, Liverpool, United Kingdom
    2. Department of Physics, University of Liverpool, Liverpool, United Kingdom
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  • Graham J. Kemp,

    1. Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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  • Margaret M. Roebuck,

    1. Musculoskeletal Science Research Group, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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  • Simon P. Frostick

    Corresponding author
    1. Musculoskeletal Science Research Group, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
    • Musculoskeletal Science Research Group, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom. T: +44-0-151-706-4120; F: +44-0-151-706-5826;
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Abstract

Studies of normal shoulder function have often failed to consider the inter-relationship between different muscle groups in activities relevant to daily life. Upper limb functional status was assessed in 12 healthy male volunteers using the Functional Impairment Test-Hand, Neck, Shoulder and Arm test (FIT-HaNSA). Electromyography was then used to study the activity and coordination of 13 muscles (10 by surface electrodes, 3 by fine-wire intramuscular electrodes) around the shoulder during a dynamic movement task based on the shelf-lifting task in FIT-HaNSA. Muscles were grouped for analysis into deltoid (anterior, middle, and posterior divisions), adductors (latissimus dorsi and teres major), rotator cuff (supraspinatus, infraspinatus, and subscapularis), and elbow flexor (brachioradialis, biceps brachii) groups. There were no significant inter-session effects. Using cross-correlation analysis to investigate the whole time-course of activation, there were highly significant positive correlations (p < 0.001) between the deltoid and rotator cuff, the deltoid and adductor and the adductor and rotator cuff groups, and a significant negative correlation between the deltoid and elbow flexor groups (p = 0.031). We conclude that the deltoid, adductor, and rotator cuff muscles all contribute to the muscular component of glenohumeral joint stability. Muscular stability can be adapted as required to meet task-specific demands. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:53–60, 2012

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