“” Uncommon Points from Weighted Ball Research - Driveline Baseball

Uncommon Points from Weighted Ball Research

| Blog Article
Reading Time: 10 minutes

Previously, we’ve discussed various updates on weighted-ball research: both on biomechanical findings from ASMI and from a variety of long-term training programs.

More research is a good thing, and as we look back on what we think we know, there are some interesting points that are not often discussed but important to consider.

Pulldowns and Bullpens: A Different Look

We’ve discussed the findings from ASMI’s biomechanical look a 4- to 7-ounce balls numerous times. One of the big takeaways from the paper was that 5-ounce throws off the mound had a statistically insignificant difference in torque when compared to pulldowns.

Pulldowns were slightly higher on average, and while there could have been bigger individual differences, this was still an important finding.

The goal of pulldowns is to match or slightly exceed torques seen in a bullpen as a training stimulus. Seeing that the difference between the mound and pulldowns was statistically insignificant means that that training stimulus meets our intention.

But there is a way to frame this finding differently.

Let’s say there is a coach who sees someone pulling down and believes the following:

“Pulldowns must be twice as stressful as pitching!”

This is not an uncommon position.

Looking from this viewpoint at ASMI’s findings you can see that pulldowns are less stressful than previously believed. But you can also come to the belief that throwing bullpens is more stressful than previously thought.

“I thought pulldowns were twice as stressful at pitching but when I found out that they were almost the same I realized I need to do a better job scheduling and warming up my pitchers to pitch.”

This difference seems to be largely based on perception. Most baseball players are used to throwing a high number of bullpens; less are used to pulling down.

Pulling down once a week may be called aggressive, whereas doing one bullpen a week may be called not enough work. Even though our current understanding of the torques of bullpens and pulldowns states that they are statistically insignificant.

Some may realize there is little difference and think they can pulldown as much as they throw in bullpens. But, doing 50 pulldowns is excessively unnecessary, and throwing 50 pitches in a bullpen needs more planning than often thought—and might be equally unnecessary.

In reality, bullpens likely need to be considered more “stressful” or intense than they currently are, both from a health perspective and from a performance perspective.

This may be a case where we are focusing too much on the specific effects of weighted balls and missing the improvements that still need to be made with workload management.

Whether using weighted balls or not, there is still much to be gained in both preparing to throw a bullpen and managing of frequency and intensity of bullpens.

External Rotation and Stress: Does Theory Match Up With What We Know Now?

Range of motion concerns have been a critique to throwing weighted balls, with research showing there can be a gain in external rotation and a loss of external and internal rotation, depending on the programming.

While the theory for those concerns is simple—that the heavier weight causes more external rotation— research has suggested that more external rotation can be more stressful on the elbow.

So, that part should be clear. We don’t have data on the biomechanical effects of balls 8-ounces or heavier, but we have a place to start with 4- to 7-ounce balls.

Now, considering this theory and looking at the biomechanical data that we’ve seen can be confusing. In this theory, ASMI’s study should show that 6- and 7-ounce balls cause more torque on the elbow and shoulder because of increased external rotation. But ASMI showed the 6-ounce ball as causing less elbow and shoulder stress than the regular baseball and the 7-ounce baseball even less than the 6-ounce.

This leads to some interesting questions:

  • If weighted balls (each ball heavier than 5 ounces) lead to more external rotation but less torque, what is the cause?
  • If these balls do increase external rotation, is gaining more external rotation still a negative if it can be achieved with less shoulder and elbow torque?
  • Do 6- and 7-ounce baseballs cause less torque than a 5-ounce in part because external rotation may be statistically insignificant? If so, is there a specific ball weight where external rotation starts to statistically significantly increase or decrease?

We’ve tried answer some of these questions before, and the answers were still mixed. We didn’t use our motion capture lab, but we used the Motus sleeve to measure Plyo Ball ® velocities and regular Plyo Ball ® throws. The amount of external rotation changes with each drill, and we saw the highest external rotation with the lighter balls.

Although there isn’t current research on the biomechanical differences of heavier weighted balls, we do have some data comparing pitching to football passing, which was first published in 1996.  (link to study updated 9/4/18)

While football passing and pitching are obviously different, it’s the closest data we have right now so it’s worth taking a look.

Remember a football (14- to 16-oz) weighs approximately three times the weight of baseball (5 oz).

Here’s what they found in relation to external rotation and elbow and shoulder torques.

Note: This study compared 26 pitchers to 26 quarterbacks. Results might differ slightly if the same players performed both the football throw and pitching.

So, when looking at comparing different objects at different weights, we see that pitching has significantly higher external rotation, whereas the elbow torques were not significantly different.

In the conclusion, the researchers wrote, “Football passing did not produce greater forces or torques.”

Clearly there are difference between football passing and pitching. The motions are often taught differently and they have different volumes and intensities in regards to programming which may play a role in the measurements.

Another look at external rotation and weighted balls can be found in a thesis titled “The Effect of Throwing Under- and Over-Weight Baseballs on the Pitching Motion.”

The methods were different than the most common way of measuring torque. They were measured using markers that were put on using straps, meaning there may be more error than a regular lab with markers stuck on individually.

That being said, the only ball that was significantly different in regards to external rotation was the lightest ball thrown, the 3 ounce.

More work should be conducted on the biomechanics of weighted balls since the belief that “more weight equals more external rotation which equals more stress” is not a clear conclusion from the biomechanical data available.

There are also concerns on how weighted balls affect passive range of motion. This is undoubtedly related to what happens biomechanically when throwing, both with and without weighted balls. As we stated earlier, we’ve seen that passive external and internal rotation can change, both an increase or decrease. Ideally we stay away from significant increases and decreases of range of motion with athletes who are already in a normal range.

So, there appears to be different effects depending on the programming and what athletes do mobility and strength wise. Which is why it’s important in the future to also consider what athletes do outside of throwing.

Ideally we can learn more biomechanically about heavy weighted balls, while learning from the results of other papers. This can help with programming ideas, which may work and which may be too much, and help use use assessments to drive athletes towards the right program for them.

Weighted Balls Don’t Just Train the Arm

This was discussed in an earlier article on weighted-ball training, but it bears repeating and expanding upon.

The ASMI study looking at 4- to 7-ounce balls found significant differences (p<0.05) among ball weights between both pelvis angular velocity and upper trunk angular velocity. While the researchers also suggest that “these differences were small and probably of little clinical relevance,” they still occur even though the ball weight changed by, at most, 2 ounces.

This leads to the question, What differences would be seen then with ball weights that are heavier than 7 ounces? Knowing there can be differences by just changing an ounce means there are likely bigger differences at heavier weights.

Although they are obviously coached very differently, there were also differences seen between pitching a baseball and throwing a football. Many of these differences were quite large.

This brings up the more relevant question of how many of these differences in movement are because of the weight change (and size) and how much of the difference is due to the coaching.

Because if there were changes that could be seen just from changes in weight, that would open up the possibility that certain weights could be aimed at specific movement changes, arm action while or body wise. Of course, there would still be difficulty in figuring out how much change is coming from changing the environment (ball weight) and which is coached.


  • If you think that pulldowns are far more stressful than pitching, know that the difference is statistically insignificant and bullpen/pitching warm-ups and scheduling should be treated more seriously.
  • The current biomechanical research does not draw a straight line between a heavier ball weight and more external rotation. More biomechanical data should be conducted on heavier weighted balls to examine what the acute biomechanical effects are. More long-term studies of varying programming should be conducted to examine the changes of passive range of motion.
  • Biomechanical data supports the idea that changing ball weight causes small changes in movement outside of just the arm. It’s unknown if this pattern continues, or to what degree, with heavier ball weights. Long-term biomechanical changes are not known and should be researched under a variety of training programs.

This article was written by Research Associate Michael O’Connell

Comment section

Add a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

    Your Cart
    Your cart is emptyReturn to Shop
      Calculate Shipping