Acute effects of weighted baseball throwing programs on shoulder range of motion.

Sports Health. Sep/Oct 2020;12(5):488-494. Reinold MM, Macrina LC, Fleisig GS, Drogosz M, Andrews JR.

Background: The purpose of this study was to examine the acute effects of throwing differently weighted baseballs on shoulder ROM. By analyzing these differences, it may be possible to determine the specific weight range that may lead to the greatest increase in ROM and potential injury risk.

Conclusion: Based on the results of this study, throwing with weighted baseballs causes an immediate increase in shoulder ER ROM. This change in ROM is more pronounced with extremely heavy balls. It is not completely known why these changes occur; however, it appears that throwing weighted balls at maximum intensity on flat ground is more stressful than pitching off a mound. This may provide a neurophysiological desensitization of the GTO mechanoreceptors and may decrease the protective mechanism of the shoulder internal rotators, allowing for more shoulder ER and velocity, but also may result in more stress and injury rates. The current study results may be used to develop more scientifically validated weighted ball programs. The use of heavier balls should be incorporated with caution, as both increased shoulder rotation and injury rates have been observed, and ROM should be monitored during implementation of these programs.

See abstract.