When someone has rounded shoulders, the back part of their shoulder muscle might work too hard when rotating the shoulder outward. This could throw off the normal muscle balance around the shoulder joint and lead to shoulder problems.

The study looked at people with rounded shoulders and found that their posterior deltoid muscle works too hard during shoulder rotation exercises, which throws off the muscle balance around the shoulder joint. Using special biofeedback helped them use the right muscles better, supporting the idea that this imbalance could cause shoulder problems.