Effects of forward head and rounded shoulder posture on scapular kinematics, muscle activity, and shoulder coordination Public Deposited

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  • March 20, 2019
Creator
  • Thigpen, Charles A.
    • Affiliation: School of Medicine, Department of Allied Health Sciences, Curriculum in Human Movement Science
Abstract
  • Forward head and rounded shoulder posture (FHRSP) has been identified as a potential risk factor for the development of shoulder pain. The mechanism through which forward head and rounded shoulder can facilitate shoulder injury is not well understood. Altered scapular kinematics, muscle activity, and shoulder joint coordination due to FHRSP may lead to the development of shoulder pain. However, there is little evidence to support the influence of FHRSP on scapular kinematics, muscle activity, and shoulder joint coordination. Therefore, the purpose of this study was to compare scapular kinematics, muscle activity, and shoulder joint coordination in individuals with and without FHRSP. Eighty volunteers without shoulder pain were classified as having FHRSP or ideal posture. An electromagnetic tracking system together with hard-wired surface electromyography was used to collect three-dimensional scapular kinematics concurrently with muscle activity of the upper and lower trapezius as well as the serratus anterior during iv loaded shoulder flexion and an overhead reaching task. Separate mixed model analyses of variance were used to compare three dimensional scapular kinematics, muscle activity, and shoulder joint coordination during the ascending and descending phases of the loaded flexion and overhead reaching tasks. Individuals with FHRSP displayed significant increases in scapular upward rotation, internal rotation, and anterior tipping during the loaded flexion and reaching tasks. Significant decreases in serratus anterior muscle activation during the ascending phase of the flexion and reaching tasks were also noted. These scapular kinematic and muscle activation patterns are similar to those reported in individuals with shoulder pain. Additionally, uncoupled scapulohumeral coordination strategies were also observed for scapular upward rotation and anterior tipping. The observed uncoupling suggests an out-of-phase relationship between the humerus and these scapular rotations in individuals with FHRSP. Considered together, these results suggest FHRSP influences scapular kinematics, muscle activity, and shoulder joint coordination. FHRSP and its effects on shoulder kinematics, muscle activity, and shoulder coordination should be examined as a potential risk factor in the development of shoulder pain. Assessment and treatment of FHRSP should be considered in the prevention and interventions of shoulder pain.
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  • In Copyright
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  • Padua, Darin A.
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