Source credit: Based on the PubMed-listed Sports Health article, PubMed 42343223, DOI 10.1177/19417381261457121.
A new Sports Health study suggests overhead shoulder adaptations can show up early in competitive volleyball players, including measurable differences in range of motion, strength, and dynamic stability.
The cross-sectional study evaluated 108 high-school volleyball players, including 49 boys and 59 girls. Researchers compared the dominant and nondominant shoulders using range-of-motion testing, isometric strength measures, joint-position sense, acromiohumeral distance, and upper-quarter Y-balance performance. They also explored whether attack form was linked with shoulder asymmetry.
Both boys and girls showed a familiar overhead-athlete pattern: less internal rotation on the dominant side, more external rotation, and reduced total rotational motion. Boys also had higher normalized internal- and external-rotation strength and stronger upper-quarter Y-balance results across most directions.
The attack-form analysis was more exploratory. Greater internal-rotation strength asymmetry and smaller inferolateral reach asymmetry were associated with using a bow-and-arrow or circular swing, but the authors cautioned that those findings should be interpreted carefully, especially because the female-only subgroup did not show significant attack-form differences.
Why it matters for lifters
For lifters and coaches, the study is a useful reminder that shoulder training is not only about pressing strength. Athletes who throw, spike, serve, swim, or do high volumes of overhead work may develop side-to-side differences long before they feel injured.
That does not mean every asymmetry is automatically a problem. Sport-specific adaptations can be normal. The practical point is to monitor the pieces that matter: internal-rotation range of motion, external- and internal-rotation strength balance, scapular control, and upper-quarter stability.
For bodybuilding and strength training, the same logic applies to programming. Heavy pressing, pull-ups, Olympic-lift variations, and overhead accessories should be balanced with rotator-cuff work, controlled rows, landmine or incline options when needed, and enough recovery from repeated overhead stress.
What to watch next
Watch for longitudinal research that follows young overhead athletes across a season to see which shoulder profiles predict pain, time loss, or performance changes. A one-time testing snapshot can describe adaptations, but it cannot prove which differences cause future injuries.
Also watch for practical thresholds that coaches can use outside a lab. The most useful next step would be clear guidance on when shoulder asymmetry is expected for a sport and when it should trigger an individualized mobility, strength, or workload adjustment.
Health disclaimer: This article is for informational purposes only and is not medical advice. Shoulder pain, loss of range of motion, or weakness should be evaluated by a qualified health professional, especially for athletes returning from injury or increasing overhead training volume.