Weighted ball use as a method for pitchers to increase velocity is certainly a hot topic these days and a quick you tube search will provide you with enough videos of pitchers doing a wide variety of weighted ball drills to keep your heart content! Likewise it seems like there is little regard given to extreme use of weighted baseballs and injury risk. It’s like the old adage: “an apple a day keeps the doctor away,” has been applied to weighted baseball use for anyone and any team regardless of training age, pitching experience, physical ability, work capacity etc…. I’m am not at all bashing weighted baseball use, in fact I have weighted baseball’s in my facility from 3oz-12oz and plyocare balls in my facility up to 2lb, that we do use on occasion with certain athletes. Likewise research has shown that weighted balls do work to increase pitching velocity as well as have been shown to be relatively safe following simple protocols. In fact, I published a post a while back discussing weighted ball use and youth pitchers:
Weighted baseball and youth pitchers
Where I feel the issue lies is the mad rush to follow the masses and chase that 100MPH plus run and gun throw on the radar gun even though we still have very limited research on using weighted baseballs at extremely high velocities or with extremely high intensity and/or volumes. Weighted baseball programs are being implemented across the county among colleges and high schools at a rate I believe is too fast based on new research and what we still don’t know.
Mike Reinold just finished a very interesting study regarding weighted baseball use and the adaptations it causes. The study was performed on high school baseball players for a 6 week duration. The end results were a 2.6mph increase in velocity along with a 5 degree increase in external rotation range of motion and total range of motion (IR plus ER) in the dominant throwing arm. Both statistically significant compared to the control group.
Obviously the increase in throwing velocity is appealing. However, the increase in shoulder external rotation of 5 degrees in just 6 weeks may be an issue to explore further with weighted ball use. In part due to a recent study by Camp et al., just published in the August 2017 edition of the American Journal of Sports Medicine. The Relationship of Throwing Arm Mechanics and Elbow Varus Torque
The authors placed a motus elbow sleeve on 81 professional pitchers and monitored them over the course of 82,000 total throws. One finding of note was that an 8 degree increase in shoulder external rotation range of motion resulted in a 1-Nm increase in elbow varus torque. Any increase in elbow varus torque is not a good thing as too much elbow varus torque over time is a leading contributor to elbow injuries. Medial Elbow Injury in Young Throwing Athletes In addition, excessive shoulder external rotation has also been shown to increase valgus stress on the elbow. Baseball pitching kinematics, joint loads, and injury prevention
Likewise, excessive shoulder external rotation produces greater tension on the biceps and labrum, a peel back mechanism that may result in a SLAP tear Baseball pitching kinematics, joint loads, and injury prevention
While we can’t say for certain if the duration of Mike Reinold’s study would have been longer than six weeks that a larger change in shoulder external rotation range of motion would have been present. It’s still a point to consider because 5 degrees of ER gain is not far off from the 8 degrees of ER gain reported by Camp et al., that caused an increase in elbow varus torque. In addition, any gains in shoulder external rotation in an athlete already displaying excessive shoulder external rotation range of motion may increase stress on the biceps and labrum.
Another study recently published by Glenn Fleisig and his fellow research staff at the American Sports Medicine Institute looked at differences in stress levels pitching 4,5,6 and 7oz balls from the mound and using a crow hop throw from flat ground. The authors did report arm torque and forces increased as ball mass decreased. However, the most interesting finding was all the flat ground crow hop throws resulted in greater shoulder internal rotation velocity and varus elbow torque compared to same weight pitches off the mound.
Biomechanics of weighted ball use
It’s becoming more and more common to include a variety of overload and underload (as low as 3 ounces) throws from a crow hop or from an all out sprint as part of weighted baseball programs. Therein lies the unknown risk. We know from Dr. Fleisig’s study, arm torque and forces increase as ball mass decreases. We also know crow hop throws resulted in greater varus elbow torque than standard mound pitching. We know from research that excessive elbow varus stress is a leading cause of elbow injuries.
What we don’t know is if greater stress results from throwing a baseball; be it overload or underload for extremely high velocity above those reached in a normal pitching situation while using a crow hop or full speed run and how much of that stress may be beneficial to create load tolerance versus how much stress is too much and will result in tissue breakdown.
Likewise, we know from one peer reviewed study (Reinold), shoulder external rotation range of motion has been shown to increase in a short amount of time as a result of weighted baseball use. We also know shoulder external rotation increases of more than 8 degrees have been shown to result in a 1-Nm increase in elbow varus torque and excessive shoulder external rotation range of motion is a factor in SLAP tears and also increases elbow valgus stress.
What we don’t know was what caused the gain in shoulder external rotation in the Mike Reinold’s study. Was it the use of heavier weighted baseballs; more overload resulting in more shoulder ER or was it the underload baseball; faster shoulder rotational velocities forcing greater ER? Nor do we know if those findings would be replicated in other studies or if ER gains would have been greater over a longer duration.
Mike Reinold did speculate the quick gain in ER came as a result of the supporting structures of the shoulder becoming looser, or more lax, thus creating anterior shoulder instability which in turn allowed for greater ER ranges of motion to be displayed. If that is the case, that is an issue in and off itself because anterior shoulder instability/joint laxity may contribute to shoulder injuries.
Kinetics of baseball pitching with implications about injury mechanisms
Without a doubt, research exists showing weighted baseballs are able to be used safely and to increase velocity with conservative, structured programs. However, those programs were implemented in a very controlled research setting. Many programs are now being implemented across full college, high school and youth teams without the ability to properly control intensity, volume, recovery or even knowledge of shoulder/elbow biomechanics or injury mechanisms. Likewise, baseball pitchers across a team will have many different shoulder and elbow adaptations as a result of their own throwing history. Some of those adaptations may not warrant a weighted ball throwing program at all, yet some may benefit from it. Finally, the potential results of a weighted baseball program, be it increased shoulder external rotation range of motion or even an increase in velocity may be more than that specific pitcher is physically prepared to handle at that point.
In conclusion, there is enough new research on weighted baseball use combined with what we already know about shoulder and elbow injury mechanisms and with what we still don’t know about high intensity throws at extreme velocities, extreme ball weights or over extended periods of time to urge caution when implementing a weighted baseball program. They do work, but they are not without risk and there is still much to learn.
Mike Martin 
There is one issue I have with this article. Calling Reinhold’s study “peer reviewed” is simply wrong. It hasn’t even been published yet. We don’t know the specifics of the methodology and, because of that, can’t be replicated, which is a staple of “peer review.”
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Thanks for your comment Richard. The study is currently in the publishing process so by semantics you are correct. It has not officially been released in a journal, but Mike Reinold himself has stated it is peer reviewed and awaiting publishing. I understand what you are saying and yes, no one has fully been able to see all the methodology in print.
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The problem is that Mike used a program that was brutal. He used 3 lb. balls in run and guns. He used kids as young as 14. From what we do know, there was no ramp up phase to his program. He so claims that it was done in partnership with ASMI, who won’t confirm that. Without knowing the methodology and without having the ability to replicate and confirm his findings, his results can’t be relied upon to support any argument. The fact he says it’s peer reviewed when it hasn’t been published should immediately tell you he doesn’t understand what the term means and repeating it gives it weight it has not yet earned. It may have relevance later, but not now. In fact, how often do you see organizations that do serious work in the field tout their results before publishing?
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With all due respect Richard, there are a few statements you make that aren’t correct. He actually used 2lb ball, not 3lb. The kids were between 16-18 yrs old. The 2lb balls throws were actually 3% of the whole weighed ball program. I am pretty sure he would not get away with putting ASMI’s name on this study in so many public forums if they were not involved. And Driveline baseball puts out significant info that is not peer reviewed.
I am in no way anti weighted balls or anti-driveline. In fact we have Driveline weighted balls at my facility. Simple fact is, my blog post is simply to bring awareness that weighted baseballs are not for everyone and if coaches/players automatically think they are safe for their whole team or for them to use, they are misinformed
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No, you are using the data responsibly except for referring to it as “peer reviewed” which gives it more weight than it has yet earned. Yes, 2 lb. – I was starting to type 32 ozs and switched to lbs. However, you’re wrong about the age. Check it again. From his article: “38 youth baseball pitchers with the mean age of 15 years old met these criteria and agreed to participate.” They were 14-18.
The fact that the 2 lb. balls only made up 3% of the throws is inconsequential. It should be 0% of run-and guns. Likewise with the one pound balls . You are correct about the possibility of misuse, but that’s my point. If I wanted to actually devise a WB program that could harm kids, I would design one a lot like his. No ramp up period and use high intent run-and-guns with inappropriately high weights.
The other problem I have is an ethical one. Mike held the position long before he started this study that the two biggest factors in the rise in pitching injury rates were weighted balls and long toss. So, to prove his point, he signs up kids as young as 14 and 15 to participate in a program that he sincerely believes is injurious? If he were to follow 38 kids who were already involved in WB programs and track their progress and injuries, that would be one thing, but this is different.
Now, I know you only used his work as it pertains to ER ROM and the possible link to injuries. I don’t really have a problem with that.
As to Driveline, it’s important to note that they don’t do studies. They do research. That’s different. They are more in the business of replicating other studies and then doing the research to explain the results.
I also didn’t write about the peer review process very effectively. Peer review is commonly applied pre-publication, but is done rather timely to get a paper to publication. Also, ASMI really didn’t have much to do with this study and don’t be surprised if neither Fleisig or Andrews appears on the byline when/if it’s published.
I just discovered your work. Keep it up. The more info available to us lowly pitching coaches, the better.
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Thanks Richard. The one reason I say they were 16-18 yrs old is because I just heard him speak at a conference last night and he discussed this study. He said the kids were between 16-18 actual years old, but something to do with how research actually uses ages that they were classified as 15-18. I’m just telling you what he said. Can’t say right/wrong.
You make a lot of great points and can certainly make case he should not have used 2lb ball run and guns. He defended it last night but saying that kids come into his facility having used 2lb balls in run and guns prior and they are used by some coaches out there so that’s why he included them.
Yes, Driveline puts out a lot of good research (I actually included some in my blog on youth curveballs), but I considered that to be basically same as Mike Reinold’s study. I do also know Drivline has some peer reviewed studies going up for publication and those studies will certainly help (hopefully) shed some more light on weighted ball use and who/when/why should use them. Thanks for reading!
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