Three-dimensional kinematic analysis of glenohumeral, scapular, and thoracic angles at maximum shoulder external rotation associated with baseball shadow pitching: comparison with normal pitching.
Shogo Okamoto, Yasuhiro Endo, Ryuta Saito and 2 others
PMID 30034102WHAT IT FOUND
When healthy pitchers performed shadow pitching with a towel instead of throwing a ball, their shoulder reached a smaller external rotation angle.
Glenohumeral rotation was also smaller, while scapular and thoracic angles were similar.
Key findings
01Shadow pitching reached a smaller maximum shoulder external rotation angle than normal pitching (136.4 degrees versus 145.4 degrees).
02Glenohumeral external rotation at maximum shoulder external rotation was smaller during shadow pitching than during normal pitching (91.8 degrees versus 98.4 degrees).
03The relative contribution of scapular and thoracic angles to glenohumeral external rotation did not show a significant difference between shadow pitching and normal pitching.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 13 healthy male volunteers were studied, and none had shoulder or elbow injury in the preceding year, so the results may not apply to injured throwers. The researchers did not use radiography, so the angles calculated from skin markers may not match the actual joint angles inside the body. Skin movement and movement of the attached bars could affect the measured kinematic data. The study measured joint angles only, not joint load or force, so it cannot show how much mechanical stress the shoulder experiences. Grip strength was not measured, so the explanation about relaxed gripping in shadow pitching remains speculative.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not read the smaller external rotation angles as proof that shadow pitching reduces shoulder injury or improves rehabilitation. The study measured healthy volunteers' joint angles, not injured patients, pain, or return to throwing.