Biomechanical analysis of the pitching characteristics of adult amateur baseball pitchers throwing standard and lightweight balls.
Yoichi Kaizu, Ena Sato, Takehiko Yamaji
PMID 33362352WHAT IT FOUND
Adult amateur pitchers threw heavier balls slower.
They did not experience significantly higher elbow or shoulder joint torque, but their pitching efficiency decreased, meaning they generated less speed for the same joint stress.
Key findings
01Ball speed decreased when pitching the heavier ball.
02Maximum elbow varus and shoulder internal rotation torques did not differ significantly between the two ball weights.
03Torque efficiency was lower for the heavy ball, indicating greater joint stress for a given pitch velocity.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only 20 participants, which limits the generalizability of the findings. All pitches were thrown on flat ground, not from a pitching mound, which can alter kinematics and kinetics. Lower extremity mechanics were not analyzed, despite their known importance in pitching. Only two specific ball weights (110 g and 145 g) were tested, so results may not apply to other weights. The study measured mechanics, not actual injury rates, so the clinical link to injury prevention is inferred rather than proven.
Declared interests
The authors have no conflicts of interest to declare.
The easy way to misread this
Do not assume that heavier balls are safe for injury prevention simply because peak joint torque did not increase. The study showed decreased pitching efficiency, meaning the joints experience more stress relative to the ball speed generated, and the sample size was too small to draw definitive clinical conclusions about injury risk.