Effects of weighted baseball throwing during warm-up on ball velocity and upper extremity muscle activation in baseball pitchers.

The objective of this study was to investigate the changes in the muscle activation of high school and college baseball pitchers during throwing of the ball with maximum effort (TBME) using a regular baseball (RB) subsequent to using a light baseball (LB), RB, and overweight baseball (OB) during warm-up (WU) and the resulting changes in the pitch velocity. The study aimed to use the findings in providing basic data for a training program designed to increase the pitch velocity of baseball pitchers. The study population consisted of 12 high school and college baseball players. The study measured and analyzed the upper extremity muscle activation and ball velocity in the stride, arm cocking, and acceleration phases during TBME using an RB subsequent to using an LB, RB, and OB during WU. During WU, the ball velocity was higher when pitching with an LB than with an RB or OB and when pitching with an RB than with an OB. However, there were no significant differences in the ball velocity when pitching with an RB during TBME. In conclusion, WU using weighted baseballs resulted in varying muscle activations, and although the velocity decreased when pitching with an OB, no difference was found during TBME using an RB. Therefore, it is believed that using weighted baseballs during WU does not have an effect on the ball velocity during TBME; future studies are needed on the effects through long-term training.