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BioMed Research International
Volume 2014 (2014), Article ID 583951, 9 pages
Research Article

Effects of Repetitive Shoulder Activity on the Subacromial Space in Manual Wheelchair Users

1Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, University of Pittsburgh, Pittsburgh, PA 15206, USA
2Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA 15260, USA
3Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
4Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, PA 15213, USA
5Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA 15260, USA

Received 15 March 2014; Revised 10 June 2014; Accepted 17 June 2014; Published 20 July 2014

Academic Editor: Sonja de Groot

Copyright © 2014 Yen-Sheng Lin et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study investigated (1) the effect of repetitive weight-relief raises (WR) and shoulder external rotation (ER) on the acromiohumeral distance (AHD) among manual wheelchair users (MWUs) and (2) the relationship between shoulder pain, subject characteristics, and AHD changes. Twenty-three MWUs underwent ultrasound imaging of the nondominant shoulder in an unloaded baseline position and while holding a WR position before and after the WR/ER tasks. Paired -tests and Spearman correlational analysis were used to assess differences in the AHD before and after each task and the relationships between pain, subject characteristics, and the AHD measures. A significant reduction in the subacromial space ( ) occurred when subjects performed a WR position compared to baseline. Individuals with increased years of disability had greater AHD percentage narrowing after WR ( ). Increased shoulder pain was associated with AHD percentage narrowing after ER ( ). The results support clinical practice guidelines that recommend MWUs limit WR to preserve shoulder function. The isolated repetitive shoulder activity did not contribute to the changes of subacromial space in MWUs. The ultrasonographic measurement of the AHD may be a target for identifying future interventions that prevent pain.