RESEARCH REVIEW: Weighted ball training in youth baseball

By Gene Coleman, Ed. D., RSCC*E and Regan Wong, PT, DPT, CSCS

The current emphasis on pitch velocity at all levels of baseball has helped increase the popularity of weighted baseball training, i.e., throwing over weight (more than 5 ounces) and underweight balls (less than 5 ounces) in recent years. The theory behind many of these programs is that throwing weighted balls will improve arm strength, increase arm speed and improve throwing mechanics, which, in turn, will lead to improvements in throwing velocity and pitch command. While several studies have shown that weighted baseball training programs are effective at improving velocity, most pitchers, pitching coaches, sports scientists and medical personnel do not fully understand why, nor do they know the long-term effects of these programs on developing arms.

The purpose of this post is to provide a summary of the findings of a 6-week research study involving 38 baseball pitchers between the ages of 13 and 18; mean age of 15 years⁵. Pitchers were divided into experimental and control groups. Both groups threw three times per week on MWF during the off-season. All throws were made from flat ground; no throws were made from a mound. Participants threw at 75%, 90%, and 100% of their full intensity depending on the week of the training program.

The control group threw 5-oz baseballs and was not allowed to throw any overloaded or underloaded balls. The experimental group threw one set of 2-, 4-, 6-, 16- and 32-ounce balls from one knee, rocker and run and gun positions. The volume of throws was progressively increased from week to week.

Pre- and post-training tests of range and motion and force were administered using a goniometer and Motus sleeve. Throwing velocity was determined from the mean of 10 fastballs thrown with a 5-ounce regulation baseball. All throws were made from a standard pitching mound and velocity was measured using a Stalker Radar gun.

Results

Throwing Velocity

Weighted baseball training produced a 3% (2.2 mph) increase in velocity
Control group did not increase velocity
80% of weighted ball group increased velocity; 12% decreased velocity
67% of the control group increased velocity; 14% decreased velocity
Both throwing weighted balls and “normal” (5 oz) balls increased velocity in some and decreased velocity in others
Take away: No guarantee that throwing weighted balls will increase velocity

Shoulder range of motion

Weighted ball training increased external rotation by 5 degrees
Throwing a 5-oz ball did not increase external rotation
Since greater shoulder external rotation is associated with velocity, this might be a contributing factor to the increase in velocity in the weighted ball group
Takeaway: Increases in shoulder external rotation and velocity, if not properly progressed, likely place pitchers at increased risk of injury. Pitchers should build a solid kinetic chain base to help alleviate some of the shoulder and elbow stress associated with throwing at higher velocities^4,7

Shoulder strength

Weighted ball training did not increase shoulder external rotation strength
Throwing a 5-oz ball increased shoulder external rotation strength by 13%
Take away: Arm (rotator cuff) strength did not improve with weighted ball training and does not appear to aid in velocity gains after 6 weeks of weighted ball training

Arm speed

Arm speed did not increase after 6 weeks of weighted ball training or training with a 5-oz ball
Take away: Data does not indicate that weighted ball training increases pitch velocity by improving arm speed

Injuries

24% of the weighted ball group sustained an injury during training or during the season following the 6-week training program
Zero percent of the 5-oz ball training group sustained an injury during training or during the season following the 6-week training program
Injuries among the weighted ball group were primarily stress fractures of the elbow and injuries to the ulnar collateral ligament (UCL)
Take away: Force gained by increases in external rotation have been shown to create tension on the inside of the elbow (UCL)^{2, 4, 7}

Conclusions

Weighted baseball training programs may be effective at enhancing pitch velocity in some individuals but may also increase injury rates
Arm strength and speed were not changed after the training program
Shoulder external rotation in the throwing arm has been shown to be related to both pitch velocity and increased shoulder and elbow forces, therefore the increased pitch velocity in the experimental group may be related to the gain in shoulder external rotation

Who should consider weighted ball training?^{2, 3, 5}

Weighted ball programs are not the starting point when developing pitching performance, participation in such programs should be limited to:
- Players mature enough to withstand the stress of weighted ball training programs
- Skeletally mature players, i.e., those who are well into, if not completely through, puberty
- Injury free athletes with efficient throwing mechanics
- Players with at least one year of total body strength and arm care training to include arm/shoulder strength and dynamic shoulder stability

Takeaways:

Weighted ball training is effective for increasing throwing velocity, but there is also a significant risk of throwing injury in high school and younger players and both appear to be related to increases in external shoulder rotation^1, ³
Weighted ball throwing programs should not be used by skeletally immature athletes^3,5
More throws and heavier balls are not better; increasing volume and intensity increases fatigue, increases shoulder and arm stress and increases risk of injury⁶
Weighted ball programs are not appropriate for “everyone”; the risks outweigh the rewards for physically immature players and those who have not established a proper level of strength and arm care^1,3
One size does not fit all; applying generic programs to “all” players on the team is not recommended; programs should be individualized, monitored by a trained professional and implemented progressively^3,6
Throwing off a mound is more stressful than throwing off flat ground; weighted balls should not be thrown from the mound²
Programs should be scaled to the level and experience of the player⁶
Different programs should be designed based on the time of year and specific goals of the althelte⁶
Workloads should be monitored to ensure that weighted ball throws are included in the number of throws and overall program design⁶

References

Lafi, SK, et. al. The relationship between shoulder range of motion and elbow stress in college pitchers. J Shoulder Elbow Surg. 2021 Mar;30(3):504-511. doi: 10.1016/j.jse.2020.06.016. Epub 2020 Jul 7.
McKenzie, C., Unleash your pitching velocity. UnleashPitchingVelocity.com, 2018.
Meister, K., Weighted ball throwing programs. http://baseballstrength.org/weighted-ball-throwing-programs/
Melugin, HP. The evidence behind weighted ball throwing programs for the baseball player: Do they Work and are they safe? Curr Rev Musculoskelet Med.2021 Feb; 14(1): 88–94. Published online 2021 Jan 6. doi: 1007/s12178-020-09686-0.
Reinold MM, et. al., Effect of a 6-week weighted baseball throwing program on pitch velocity, pitching arm biomechanics, passive range of motion, and injury rates. Sports Health. 2018;10(4):327–333. doi: 10.1177/1941738118779909. [PMC free article] [PubMed] [CrossRef] [Google Scholar]
Reinhold, MM, et. al. The safety and efficacy of weighted baseballs. http://baseballstrength.org/the-safety-and-efficacy-of-weighted-baseballs-2/
Reinhold, MM, et. al. Acute effects of weighted baseball throwing program on shoulder range of motion. Sports Health, 12(5): 488-494, 2020, doi: 10.1177/1941738120925728. Epub 2020 Jun 29.

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Gene Coleman, Ed. D., RSCC*E, FACSM has over four decades as a head strength and conditioning coach (Astros) and strength and conditioning consultant (Rangers). He is Professor Emeritus in the Exercise and Health Sciences Program at the University of Houston – Clear Lake and Website Education Manager baseballstrength.org. Regan Wong, PT, DPT, CSCS, is the Major League Physical Therapist for the Texas Rangers and former Director of Sports Rehabilitation at TMI Sports Medicine in Arlington, Texas.