In 2020, American Sport Medicine Institute (AMSI) had a all-star panel of doctors and physical therapists to discuss whether weighted ball programs are a safe way to increase velocity in pitchers. The answer for youth was a resounding “no” across the board. The medical experts concluded that weighted ball programs likely add to velocity because they increase layback (i.e., external rotation) and not due to strengthening the arm safely. The additional layback adds stress to the elbow and may cause a ulnar collateral ligament (UCL) tear.
The panelists included Dr. James Andrews, Dr. David Altchek, Ken Crenshaw, Eric Cressey, Dr. Raffaele Escamilla, Dr. Glenn Fleisig, Lenny, Macrina, Dr. Eric Makhni and Mike Reinold. Dr. Andrews was universal against using weighted balls at all levels of play and did not approve of long toss either. Several of the others didn’t think throwing weighted balls was safe for skeletally immature players, but thought they could be used under supervision in specific cases for college and professional players.
At 23:35 in the video, alternative to weighted ball programs are listed as safer ways to increase velocity through resistance training using tubes or core exercises. A broader point is that regardless of the method, throwing too fast too young is likely to cause injury to the UCL. At 24:45 Dr. Andrews, elaborates about the risk of high school pitchers throwing over 85 mph and very high risk at 90 mph unless they have a genetically stronger UCL.
On a related note, a 2020 study about weighted balls by several of the panelists in the video concluded, “Throwing with overload weighted baseballs causes an immediate increase in shoulder ER ROM…the results may explain both the increase in velocity and injury rates previously observed from throwing weighted balls…Heavier balls should be used with caution, and ROM should be monitored during implementation of these programs.”