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The Relationship Between Relative Humeral Retrotorsion Difference and Shoulder Strength Measures in Collegiate
J Kaylin Kruseman1, Natalie L Myers2, Frankie-Ann McCauley3
1Memorial Hermann Health, Rockets Sports Medicine Institute, Houston, Texas, USA.
Orthopaedic Journal of Sports Medicine
|May 29, 2026
Summary
Side-to-side differences in humeral retrotorsion (rHRT) were linked to dominant arm internal rotation strength in baseball players. Playing position and limb dominance also influenced shoulder strength, highlighting their importance in rotational profiles.
Area of Science:
- Sports Medicine
- Biomechanics
- Orthopedic Surgery
Background:
- Humeral retrotorsion (HRT) is associated with throwing adaptations in baseball athletes, influencing range of motion, capsule extensibility, velocity, and injury risk.
- Rotational strength deficits are linked to increased injury risk, but the impact of side-to-side differences in HRT (relative HRT [rHRT]) on rotational strength profiles remains unaddressed.
Purpose of the Study:
- To investigate the relationship between relative humeral retrotorsion (rHRT) and shoulder strength measures in uninjured collegiate baseball athletes.
- To test the hypothesis that rHRT is significantly associated with shoulder external rotation (ER) and internal rotation (IR) strength.
Main Methods:
- A cross-sectional study involving 182 uninjured male collegiate baseball athletes.
- Bilateral isometric shoulder strength was measured using a handheld dynamometer; humeral torsion was assessed via diagnostic ultrasound.
- Hierarchical regression analysis was employed to determine the contribution of rHRT, playing position, and limb dominance to shoulder strength measures.
Main Results:
- Relative HRT did not significantly predict dominant or nondominant limb ER strength, nor nondominant limb IR strength.
- Relative HRT significantly improved the prediction model for dominant limb IR strength, though it was not an independent predictor.
- Playing position (pitcher) and limb dominance (left-handed) significantly improved regression models for dominant limb IR strength.
Conclusions:
- Relative HRT is associated with dominant limb internal rotation strength in collegiate baseball athletes.
- Playing position and limb dominance are independent positive contributors to shoulder internal rotation strength prediction models.
- These findings demonstrate an association between shoulder IR strength and rHRT, playing position, and limb dominance in this cohort.
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