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Scapular force: Couple ratios in healthy shoulders - An observational study reflecting typical values
Sonia Briel1, Benita Olivier1, Witness Mudzi1
1Department of Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
The South African Journal of Physiotherapy
|August 8, 2022
Summary
This study determined typical scapular force couple strength ratios in healthy shoulders. Findings reveal specific ratios for dominant arms in women and men, crucial for scapular stability.
Area of Science:
- Biomechanics
- Human Anatomy
- Musculoskeletal Research
Background:
- Scapular stability relies on scapular muscle action, not bony structure.
- Scapular muscle force couple ratios are not well-established.
Purpose of the Study:
- To quantify typical scapular force couple strength ratios.
- To compare these ratios in healthy male and female shoulders.
Main Methods:
- Quantitative, cross-sectional study design.
- Handheld dynamometry used to measure muscle strength (kgf) of serratus anterior, trapezius, and rhomboid muscles.
- Force couple ratios calculated for dominant and non-dominant shoulders.
Main Results:
- Specific force couple ratios were determined for dominant arms in women and men.
- Examples include upper trapezius:lower trapezius ratios of 3.63 (women) and 2.70 (men).
- Other ratios like serratus anterior lower fibres:lower trapezius and middle trapezius:serratus anterior upper fibres were also quantified.
Conclusions:
- Established specific force couple strength ratios for scapular stabilizers in healthy individuals.
- Provided normative data for dominant and non-dominant shoulders in both sexes.
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