Sports participation and humeral torsion.
METHODS
Cross-sectional study.


OBJECTIVE
To examine differences between arms in humeral torsion in adult and adolescent throwing and nonthrowing athletes, and nonathletic adults.


BACKGROUND
It is hypothesized that humeral retrotorsion develops by, and is beneficial for, throwing. Thus throwers should demonstrate greater retrotorsion in their dominant arm relative to their nondominant arm and have more side-to-side retrotorsion difference than nonthrowing groups. In addition, adult throwers should have a greater side-to-side retrotorsion difference than adolescent throwers, and swimmers should not demonstrate a retrotorsion difference.


METHODS
Using ultrasound to standardize the location of the bicipital groove, the amount of humeral torsion was measured in both arms of male baseball players (85 adult, 35 adolescent), female softball players (16 adult, 37 adolescent), 29 elite adolescent swimmers (19 female), and 16 nonathletic adults (8 female).


RESULTS
More retrotorsion was found in the dominant arm of almost all throwing athletes, irrespective of their gender or whether they were adults or adolescents (mean+/-SD side-to-side difference, 11.9 degrees+/-10.5 degrees). This difference was less for swimmers (6.4 degrees+/-9.9 degrees) and nonathletic adults (1.3 degrees+/-8.9 degrees).


CONCLUSIONS
Greater dominant armhumeral retrotorsion is observed contingent with participation in throwing sports.
Faculty of Health Sciences, University of Sydney, Sydney, Australia. whiteley.rod@gmail.com
Rod J
RJ
Whiteley
Karen A
KA
Ginn
Leslie L
LL
Nicholson
Roger D
RD
Adams
D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000502:physiology*; D015994:Incidence; D008297:Male; D009517:New South Wales / Q000453:epidemiology; D016059:Range of Motion, Articular / Q000502:physiology; D012307:Risk Factors; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000502:physiology*; D013177:Sports / Q000502:physiology*; D014102:Torsion Abnormality / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000517:prevention & control; D014463:Ultrasonography; D055815:Young Adult