Background: The shoulder serves as a critical link between the upper limb and the trunk, providing essential stability for functional movements. Impaired trunk stability can alter patterns of shoulder complex muscle activation, potentially compromisin...
Background: The shoulder serves as a critical link between the upper limb and the trunk, providing essential stability for functional movements. Impaired trunk stability can alter patterns of shoulder complex muscle activation, potentially compromising upper limb performance and promoting compensatory movement strategies. We investigated the effects of external trunk compression on shoulder rotator strength and scapular muscle activity in healthy young adults to determine the most effective trunk compression site.
Methods: Twenty-eight healthy adults in their twenties participated in this study. Shoulder internal and external rotational strength was measured under three experimental conditions: no trunk compression, pelvic compression only, and combined thoracic and pelvic compression. Electromyographic activity of the upper and lower trapezius, serratus anterior, and middle deltoid muscles were recorded as the participants performed tasks to evaluate changes in muscle activation associated with each compression condition.
Results: Both internal and external shoulder rotational strength increased with increasing external trunk support. Electromyographic activity measured in scapular and shoulder muscles showed significant differences across the three compression conditions (p<.01). Muscle activation exhibited a progressive increase corresponding with the number of applied compression sites.
Conclusion: External trunk compression can enhance shoulder rotational strength and increase scapular stabilizing muscle activation. Improving trunk stability may thus enhance performance during shoulder rotational tasks. This finding may have meaningful implications for rehabilitation programs targeting individuals with shoulder dysfunction, where incorporating trunk stabilization strategies could enhance recovery and functional improvement.