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Ginn K1, Boettcher C1, Holt K2, Halaki M3
1The University of Sydney, Faculty of Medicine & Health, Sydney, Australia, 2Australian Institute of Sport, Department of Physical Therapies, Canberra, Australia, 3The University of Sydney, Faculty of Health Sciences, Sydney, Australia
Background: Shoulder pain is a significant burden to swimmers of all ages and ability. It is the most common injury reported in swimmers and the main cause of lost training hours and, in some cases retirement, in elite swimmers. A potential causative factor of shoulder pain in swimmers is the shoulder rotation strength balance. It has been argued that, because shoulder internal rotation (IR) is performed during the pull-through (propulsive) phase of swimming strokes, shoulder IR strength increases proportionately more than external rotation (ER) strength in swimmers. It is believed that this rotation strength imbalance then leads to changes in humeral head positioning resulting in shoulder pain due to impingement. Although studies on small cohorts of amateur and low level swimmers have reported a decreased shoulder ER to IR strength ratio, these studies have not found an association with shoulder pain. The conclusion, therefore, from a recent systematic review examining the risk factors for shoulder pain in swimmers was that there is insufficient evidence to make a definitive conclusion about the contribution that shoulder rotation strength imbalance might make to shoulder pain in swimmers.
Purpose: To examine shoulder rotation strength parameters and their potential link to shoulder pain in swimmers. To eliminate swimming technique errors as a potential cause of shoulder pain, this study was performed on elite level swimmers.
Methods: Sixty-eight (male, n=40; female, n=28; age = 19.9±3.2 years) elite Australian swimmers provided demographic and shoulder pain history data prior to measurement of shoulder rotation strength with hand held dynamometry. Repeated measure analysis of variance was used to examine differences in shoulder internal rotation (IR) and external rotation (ER) strength normalised to body weight (BW) and the shoulder rotation strength ratio. Multiple regression analysis was utilised to examine the associations between shoulder rotation strength variables and shoulder pain.
Results: Mean shoulder IR strength (BW) was approximately 0.29 for male swimmers and 0.26 for females. Mean shoulder ER strength (BW) was approximately 0.19 for male swimmers and 0.18 for females. The shoulder ER: IR strength ratio was approximately 0.70 bilaterally for both male and female swimmers. There were no significant differences between dominant and non-dominant shoulders in IR or ER strength normalized to body weight (F1,66≤2.97, p≥0.090). There were no associations between any shoulder strength variables and current or history of shoulder pain (R2=0.058, p=0.46).
Conclusion(s): Despite the high IR loading associated with swimming, optimal swimming technique does not alter the normal ER:IR strength ratio at the shoulder. Swimmers performing at an elite level who report current shoulder pain or a history of shoulder pain demonstrate normal shoulder rotation strength ratios.
Implications:
Keywords: shoulder rotation strength ratio, shoulder pain
Funding acknowledgements: Not applicable
Purpose: To examine shoulder rotation strength parameters and their potential link to shoulder pain in swimmers. To eliminate swimming technique errors as a potential cause of shoulder pain, this study was performed on elite level swimmers.
Methods: Sixty-eight (male, n=40; female, n=28; age = 19.9±3.2 years) elite Australian swimmers provided demographic and shoulder pain history data prior to measurement of shoulder rotation strength with hand held dynamometry. Repeated measure analysis of variance was used to examine differences in shoulder internal rotation (IR) and external rotation (ER) strength normalised to body weight (BW) and the shoulder rotation strength ratio. Multiple regression analysis was utilised to examine the associations between shoulder rotation strength variables and shoulder pain.
Results: Mean shoulder IR strength (BW) was approximately 0.29 for male swimmers and 0.26 for females. Mean shoulder ER strength (BW) was approximately 0.19 for male swimmers and 0.18 for females. The shoulder ER: IR strength ratio was approximately 0.70 bilaterally for both male and female swimmers. There were no significant differences between dominant and non-dominant shoulders in IR or ER strength normalized to body weight (F1,66≤2.97, p≥0.090). There were no associations between any shoulder strength variables and current or history of shoulder pain (R2=0.058, p=0.46).
Conclusion(s): Despite the high IR loading associated with swimming, optimal swimming technique does not alter the normal ER:IR strength ratio at the shoulder. Swimmers performing at an elite level who report current shoulder pain or a history of shoulder pain demonstrate normal shoulder rotation strength ratios.
Implications:
- Contrary to popular belief swimming does not alter the normal shoulder ER:IR strength ratio. Swimmers performing at an elite level with and without current shoulder pain demonstrate normal shoulder rotation strength ratios.
- Because shoulder rotation strength parameters are similar bilaterally in swimmers, detection of side-to-side differences in shoulder rotation strength and/or rotation strength ratios is a significant finding with implications for the prevention and treatment of shoulder pain in swimmers.
Keywords: shoulder rotation strength ratio, shoulder pain
Funding acknowledgements: Not applicable
Topic: Sport & sports injuries; Musculoskeletal: upper limb
Ethics approval required: Yes
Institution: Australian Institute of Sport
Ethics committee: Australian Institute of Sport Ethics Committee
Ethics number: 20130413)
All authors, affiliations and abstracts have been published as submitted.
