The Safety and Efficacy of Weighted Baseballs.
Michael M Reinold, Leonard C Macrina
PMID 33842055WHAT IT FOUND
Weighted baseballs may increase pitching velocity in some athletes but not all, and a prior program showed shoulder or elbow injury in almost 25% of subjects.
Use caution with dosing and rest.
Key findings
01Weighted-ball programs did not improve velocity in everyone; some participants showed no change or a decrease.
02In the authors' prospective weighted-ball study, almost 25% of subjects sustained a shoulder or elbow injury, and most injuries occurred in the following baseball season.
03Weighted-ball throwing was associated with increased shoulder external rotation, which the review links to velocity gains and increased arm stress.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
It is a narrative review and commentary, not a new trial, so it cannot establish a causal effect or an optimal weighted-ball program. It reports many different ball weights, throws, and drills, so the effect of any single component cannot be separated. It includes the authors' own prior studies and anecdotal experience, which may introduce bias. It does not provide full methods, participant counts, blinding, or dropout handling for the cited studies. The injury finding comes from a prospective study and may not apply to all populations or programs.
The easy way to misread this
Do not conclude that weighted baseballs are a proven, safe way to increase velocity for every athlete. The review says results vary, some athletes do not improve, and a prior program reported shoulder or elbow injury.