COLORADO SPRINGS, Colo. — Right-handed pitchers show greater external rotation, humeral retroversion and shoulder flexion in their throwing arms compared with left-handed pitchers, according to a study presented here.
“Right-handed pitchers also demonstrated significant side-to-side torsion differences while left-handed pitchers did not,” Jacob Maier, MD, said at the American Orthopaedic Society for Sports Medicine Annual Meeting.
Maier and colleagues reviewed 160 right-handed and 57 left-handed pitchers from a single Major League Baseball organization from 2013 to 2020. They studied whether differences in glenohumeral range of motion and humeral torsion exist between left-handed and right-handed pitchers. Researchers evaluated range of motion and degree of humeral torsion using a goniometer and an ultrasound probe was used to determine neutral position of the shoulder.
Researchers found right-handed pitchers in the study had 10° more retroversion in their throwing arms compared with left-handed pitchers. Right-handed pitchers also had an average of an additional 13.9° of shoulder external rotation range in their throwing arm compared with the non-dominant arm. Left-handers averaged an additional 2.2° of shoulder external rotation range of motion in their throwing arm compared with the non-dominant arm.
Right-handed pitchers had significantly more internal rotation and humeral torsion, while left-handed pitchers had greater range of non-dominant shoulder flexion.