BACKGROUND & OBJECTIVE
Weighted ball programs have become increasingly popular in youth sports as increasing emphasis is placed on baseball pitch velocity and early sport specialization. This study seeks to define, explain, and quantify the adaptations seen with weighted ball programs. The purpose of this study was to explore the effects of training with a weighted ball on pitch velocity, passive range of motion (PROM), muscle strength, elbow torque, and injury.
During the baseball offseason, 38 healthy youth pitchers (age 15 +/- 1.2 years) performed a throwing program and strength training program 3 x per week for 6 weeks. Recruits were excluded if they had a history of injury in the past 12 months. The 38 subjects were randomized into a control (n = 19) and experimental group (n = 19), with the control group throwing only with 5-ounce regulation weight balls and the experimental group throwing with under and overweight balls ranging from 2 ounces to 32 ounces.
Over the course of the 6-week program, throws were performed from 3 common baseball drill positions: knee (half kneeling), rocker (similar to split stance), and run and gun (crow hop). Baseline measurements were taken at the onset of the study and then reassessed following the aforementioned 6-week intervention. Highly reliable and novel methods were used to measure some of the more difficult to quantify variables: elbow varus torque and shoulder IR velocity were measured using an elbow sleeve with an embedded inertial measurement unit and strength was measured via handheld dynamometry.
There was a 3.3% increase in throwing velocity in the training group whereas the control group did not improve velocity. The most significant and explanatory finding of the increased velocity was a 4.3° increase in external rotation passive range of