Document Type : Original Articles
Authors
1 Department of Sport Injuries and Corrective Exercises, Faculty of Physical Education & Sport Sciences, University of Guilan, Rasht, Iran.
2 Department of Physiotherapy, Faculty of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
3 Department of Sport Sciences, Faculty of Physical Education and Sport Sciences, University of Guilan, Rasht, Iran
Abstract
Purpose: This study aimed to compare the differences in shoulder strength, muscle length, and proprioception between dominant and non-dominant sides in individuals with and without uneven shoulders.
Methods: This cross-sectional comparative study examined 20 females with uneven shoulders and 20 matched controls aged 20–30, selected purposefully to compare shoulder strength, muscle length, and proprioception. Shoulder asymmetry was assessed using digital photography and analyzed via AutoCAD 2020. Muscle strength was measured with a manual dynamometer. Proprioception was evaluated by assessing joint angle reconstruction errors using a goniometer, and muscle length was determined using standardized tests. Data analysis was performed using SPSS version 22.
Results: The findings indicated significant differences between the two groups in the mean error of shoulder flexion angle reconstruction (p = 0.049, d = 0.56) and internal rotation (p = 0.037, d = 0.61), as well as in the length of the pectoralis minor (p = 0.036, d = 0.58) and levator scapulae muscles (p = 0.021, d = 0.64). Individuals with uneven shoulders showed greater side-to-side differences compared to the control group. However, no significant differences were observed in shoulder strength or the length of the upper trapezius between groups.
Conclusion: In summary, individuals with uneven shoulders demonstrated greater error in joint position sense and asymmetry in specific muscle lengths. These findings suggest uneven shoulders may be associated with impaired proprioception and altered muscle length, especially in the pectoralis minor and levator scapulae.
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