Straight Answers to Tough Questions about

Training with Weighted Baseballs

By Steve Zawrotny, MS, CSCS



Q: I’m confused; there are so many different views on what is proper training and how to increase throwing velocity… what’s right?

A: The confusion stems from the fact that some “gurus” stress either strength development at the expense of good body mechanics or good body mechanics at the expense of a well designed strength and conditioning regimen. From there, these same “gurus” attempt to expose the faults of other trainers or instructors, resulting in a climate of fear and misinformation.

There is no reason that athletes involved in refined “power” skills like throwing should disregard strength and power training, muscular endurance, and flexibility while working on developing their throwing mechanics.

That’s why it’s important to engage in workout programs that include skill work combined with resistance training. This type of training provides the opportunity to adjust your skills gradually to changes occurring in your body as a result of your training regimen.

The fact is, in order to develop your potential as a powerful ball player with a high level of neuromuscular skill, you have to know what you’re trying to accomplish and what specific demands to impose in order to properly design a strength and conditioning program that will help you achieve your objective(s).

Q: I hear that weighted baseball training is not only harmful but a waste of time and money and could eventually lead to injury. What are the facts?

A: I’ve not seen any clinical or empirical data to support this claim of harm. Because weighted implement training is relatively new to baseball, it’s easy for the uninformed to discount it. When I see claims like these from self-proclaimed “experts,” I NEVER see them supply any objective data to support their arguments. If you take a closer look at these arguments, you’ll find many contradictions.

For example, I saw one “expert” claim that weighted ball training is not used by professional ballplayers because it can cause injuries and then pointed to several pro-ball players who were injured to support his claim that weighted ball training was harmful. Interestingly, the injured players he mentioned never used weighted balls.

On the other hand, I’ve read at least a dozen well-designed clinical studies that support the use of moderately weighted baseballs for both velocity increase as well as arm-conditioning. Add to this that I’ve had hundreds of players over the years perform this type of training with NO reported problems or injuries. The body of evidence to support the safety and efficacy of this type of training is extensive and well-regarded.

So, can you get hurt training with weighted baseballs?

Yes, if done improperly – like many activities. Can you injure yourself while weight training? Can you hurt yourself by merely throwing a baseball? Of course you can, IF you do either of these activities incorrectly.

Lifting properly and throwing correctly are keys to injury prevention, to say nothing of performance improvement. Interestingly, when players get hurt because of bad throwing mechanics no one condemns the act of throwing. Yet, when a player who is throwing and doing some type of strength training sustains an injury, the strength training (general or specific, like weighted baseballs) instantly becomes the culprit.

Here’s the point: Far more players are hurt from poor throwing mechanics than from training with weighted baseballs. Used properly, moderately weighted baseballs will not only improve throwing velocity, they can properly condition the arm for the rigors of throwing. Proper training with weighted baseballs (and softballs) actually becomes an INJURY PREVENTIVE MEASURE.

Here are two unsolicited testimonials from real ball players (one a professional pitcher) who have trained with weighted baseballs:

#1  “I am coming off a shoulder injury and in the past 2 months have followed your [throwing] program and have yet to feel the slightest discomfort so far this season... After my first start I went 6 innings with no discomfort to my shoulder what-so-ever and that is twice the amount of time I would have went anytime last year, healthy or not.”     P. P., Winston Salem, NC

#2  " After my last year in the Anaheim Angels Organization I had back surgery. As a result of trying to come back too early I blew out my throwing shoulder and had an arthro cleanup and reconstructive surgery (Bankaert repair). After 3 years of rehab/physical therapy - throwing program and trying to come back over hand my velocity consistently wasn't there and the pain was still there.

"I then decided to convert to a sub-marine delivery at the same time stumbling onto Steve. I
use Steve's workouts as a part of my Daily Training Program and I have never had better results. His workouts/programs work and have helped my arm drastically. Within the last three months my velocity has gone from 84mph up to 88mph" 
Jason Anderson,
Former Anaheim Angels Organization pitcher

For those of you who would like further clinical data supporting the use of weighted baseballs, click here to see several references as well as additional info on how and why this training method works.

Q: Doesn’t training with weighted balls mess up your timing?

A: Not when training with balls weighing within 20% (above and below) of the regulation weight of your game ball (5 oz for baseball, 6.5 oz for softball). There is some data that indicates that training with what I call “heavy” weighted balls (over 6 oz for baseball, 8 oz for softball) can cause problems with mechanics which can lead to control problems or injury. Follow the 20% guideline and you’ll avoid this problem.

Q: Is lack of arm strength the primary issue for a lack of velocity in high school pitchers? Shouldn’t pitchers who throw a 5 oz ball from the mound only throw a 5 oz ball whenever they throw?

A: It’s important to avoid generalizations. Some pitchers with very poor mechanics and naturally strong arms can make significant improvement in throwing velocity just by correcting their mechanics. Likewise, pitchers with good mechanics can make vast improvements in their throwing velocity when they use appropriate strength and conditioning methods combined with a proper weighted ball throwing program.

As for only throwing a 5 oz ball, the fundamental and well-accepted principle for developing any type of fitness is the SAID principle: Specific Adaptation to Imposed Demands (Wallis and Logan, 1964). The principle simply states that to develop an optimum level of strength or conditioning you must safely and progressively increase the demands you impose on your body.

Throwing balls weighing slightly more, or less, than the standard 5 oz baseball (or 6.5 oz softball) is a type of training that conforms to this principle.  It has NEVER been shown to be detrimental to throwing or pitching performance. In fact, there is a great deal of information to support the use of moderately weighted baseballs.

Q: Don’t pitchers simply need more functional strength and mechanical adjustments to help transfer this strength to the baseball?

A: Again, it depends on the pitcher’s situation. If a pitcher has poor mechanics, I recommend that these deficiencies be corrected first. A lack of strength and power is a different matter and is approached differently.

Improving core strength, power and even flexibility can improve throwing velocity. A regimen of throwing weighted baseballs is simply another appropriate means to accomplish this objective.

Q: Can’t pitchers simply fix a mechanical fault such as weight transfer or stride length along with getting more rotational power from the pelvis and trunk and therefore throw harder?

A: Of course, and I heartily recommend that pitchers do so! Once this is accomplished, what does a player do next? Simply do more long-toss drills? Ball players have been doing long-toss all their lives. If increasing velocity was so easy to accomplish, we’d have a lot more 90+ mph throwers.

Q: Don’t those that are selling weighted baseballs actually justify velocity increases by making mechanical adjustments?

A: Obviously, I can’t speak for everyone selling weighted balls. Some may make this claim, but I don’t know why they would. I certainly do not. I have always recommended that throwing mechanics be in order before moving on to more “advanced” training such as my throwing velocity program.

In fact, my regimen doesn’t in any way address mechanics – purposefully so – because there are many good books and videos already on the market about developing proper throwing technique. In no way do I attribute the improvements made on my program to improved mechanics. Players using my program are getting results because of the combination of the throwing program itself (with PROPERLY weighted baseballs or softballs) and the strength and flexibility program for the rotator cuff.

Q: If all pitchers had to do to gain an added 10 mph on their velocity was to just purchase a set of $30 weighted baseballs, wouldn’t that be one of the most popular baseball products out there?

A: Don’t confuse the “popularity” of a product or idea with its soundness. It was once “popular” to consider the earth to be flat.

There are many reasons good ideas aren’t popular, not the least of which is a lack of knowledge of the concept in the first place. Another reason is the misinformation that is passed around as “knowledge” that ends up unnecessarily confusing and scaring people.

As correct information and success stories continue to spread about training with weighted baseballs and softballs, their “popularity” will increase.  I think that move has already begun.

Q: Haven’t weighted baseballs been around for over 30 years now and yet are hardly ever seen or used by top performing pitchers, top college or pro teams?

A: Yes, heavy weighted baseballs have been around for a while, and the science behind weighted implement training has been around even longer. Pioneered by research in the former Soviet Union, track and field athletes (hammer, javelin, and discus throwers, along with shot putters) have been safely and successfully training this way for decades.  Even sprinters and swimmers are using overload and underload training.  Compared to other sports, baseball has just been slow to adopt these safe and effective training methods.

As for the number of college or pro teams using specific-resistance and weighted implement training, don’t let their lack of understanding and acceptance of these proven training techniques guide your decision. Pro baseball in particular is NOTORIOUSLY slow to adopt new ideas while holding onto outmoded ones.  Just read the best-selling baseball book, "Money Ball" for ample proof of this.

At the same time, a lot of big leaguers do things I would never recommend to ball players. Many major league pitchers throw pitches that are not appropriate for younger pitchers. Their mechanics are often not worthy of emulation. Some chew tobacco, etc, etc. I think you get the point.

Q: Isn’t it true that the majority of youths and high school pitchers do not get very good use of their lower body and trunk? Wouldn’t this increase stress on the arm and therefore the stress placed on the arm when using weighted balls?

A: While this is a common problem, using moderately weighted balls has not been shown to be problematic for even these players. In such cases, however, I always recommend that mechanical deficiencies be corrected before engaging in weighted ball training.

Q: I saw an article that appeared in July 28 2003 USA TODAY on Tommy John’s arm surgery. Did he ever use weighted baseballs?

A: No, Tommy John never used weighted baseballs and this article never mentions weighted baseballs. It does address John’s surgery and comeback, as well as that of other players.

Finally, here are two clinical studies on the use of weighted training baseballs:

1)  Training Pitchers with Overweight and Underweight Baseballs by the American Sports Medicine Institute

A review was conducted to determine how throwing overweight and underweight baseballs affects baseball throwing velocity and accuracy. Two studies were found that examined how warming up with overweight baseballs affected throwing velocity and accuracy of 5 oz regulation baseballs. One of these studies showed significant increases in throwing velocity and accuracy, while the other study found no significant differences.

Three training studies (6-12 weeks in duration) using overweight baseballs were conducted to determine how they affected ball accuracy while throwing regulation baseballs. No significant differences were found in any study. From these data it is concluded that warming up or training with overweight baseballs does not improve ball accuracy.

Seven overweight and four underweight training studies (6 – 12 weeks in duration) were conducted to determine how throwing velocity of regulation baseballs was affected due to training with these overweight and underweight baseballs. The overweight baseballs ranged in weight between 5.25 - 17 oz, while the underweight baseballs were between 4 - 4.75 oz. 

Data from these training studies strongly support the practice of training with overweight and underweight baseballs to increase throwing velocity of regulation baseballs.  [emphasis mine]

Future research is needed to determine what effect, if any, training with overweight and underweight baseballs has on risk of injury. In addition, research should be initiated to determine whether throwing kinematics and kinetics are different between throwing regulation baseballs and throwing overweight and underweight baseballs.

2)  Journal of Strength and Conditioning Research, 2001, 15(1), 148–156 (c) 2001 National Strength & Conditioning Association Brief 

Effects of General, Special, and Specific Resistance Training on Throwing Velocity in Baseball: A Brief Review


1 Department of Kinesiology and Leisure Science, College of Education, University of Hawaii-Manoa, Honolulu, Hawaii 96822;  2 University of British Columbia, Vancouver, British Columbia, Canada, V6K2B2.

A brief quote from this study, page 5:  "Previous throwing studies have indicated that the throwing velocity of a standard 5-oz baseball can be increased significantly by overload training, or throwing a heavier baseball. In contrast, throwing velocity can also be increased using weighted implements that were slightly lighter than the standard competitive weights."

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