In baseball performance circles, body mass is often seen as an advantage. Bigger pitchers throw harder, last longer through the season, and carry the kind of durability scouts covet. But what if each additional pound on the scale also comes with a measurable increase in elbow stress? A new biomechanical analysis challenges one of the sport’s most enduring assumptions—that “bigger is better.” The findings suggest that while mass may fuel velocity, it simultaneously amplifies torque on the elbow, raising critical questions about long-term health and performance sustainability.

The Problem

Pitching injuries—specifically UCL tears—remain the defining epidemic of modern baseball. Despite advances in pitch design, workload monitoring, and surgical outcomes, the underlying mechanisms of elbow stress remain only partially understood. Coaches and athletes often prioritize velocity as the ticket to advancement, with weight gain framed as a straightforward way to add horsepower. Strength programs emphasize bulking to build “horsepower” without always quantifying the orthopedic cost. The gap in the literature has been a lack of direct data linking anthropometrics—height, weight, limb length—with varus torque, the primary mechanical load placed on the UCL.

What the Study Found

Slowik et al. (2025) analyzed 624 collegiate and professional pitchers, the largest dataset of its kind, and reported a clear trend: body weight was the strongest predictor of elbow varus torque. Mean torque across the cohort was 94.8 ± 17.0 N·m. The correlation coefficient between weight and torque was r = 0.59 (P < .001), stronger than any other variable measured. Height alone was not a dominant predictor, but the interaction of weight and height produced a similarly strong correlation (r = 0.58).

Most striking was the linearity of the finding: for every 10 N (≈2.25 lbs) increase in body weight, torque rose by 1 N·m. In practical terms, a pitcher who gains 20 pounds might experience ~9 N·m of additional torque—a material increase, considering that UCL failure thresholds are thought to fall around 32–35 N·m in cadaveric studies. Stepwise regression further identified forearm and upper arm length as additional contributors, with anthropometrics collectively explaining 38% of the variance in torque.

Why This Matters

These results land at the heart of a paradox in pitcher development. On one hand, added mass can improve stability, energy transfer, and absolute velocity. On the other hand, the study demonstrates a proportional increase in joint stress that cannot be ignored. The implications are most concerning for younger pitchers chasing weight-based velocity gains without a concurrent refinement of mechanics.

This tension echoes findings from prior research on velocity and elbow kinetics. For example, Manzi et al. (2021) demonstrated that sudden increases in velocity—rather than sustained high velocity—carry the greatest injury risk, suggesting that how an athlete adapts to load is as important as the load itself. Taken together, these studies highlight that body weight, velocity, and torque are not isolated variables but parts of an integrated stress-performance ecosystem.

How We Use This at VeloU

At Velo University, these findings reinforce the principle that size cannot be pursued as a blunt objective. Instead, we emphasize functional mass. When athletes add weight, it must be accompanied by proportional improvements in mobility, arm care, and mechanical efficiency. Our monitoring tools, from force plates to ArmCare assessments, help determine whether added body mass is contributing to force production or simply compounding torque.

In practice, this means we often individualize weight gain strategies. A 6’4” pitcher at 205 lbs with fluid mechanics may tolerate and benefit from an additional 15 pounds, while a 5’10” pitcher already operating at high torque might gain little and risk much by bulking indiscriminately. We also leverage data from studies like Gdovin et al. (2025), which highlighted the risks of training devoid of resistance, and integrate balanced approaches that consider both strength and joint loading.

Caution in Application

It’s tempting to interpret the Slowik study as a prescription against weight gain. That would be premature. Torque is only one piece of the injury-risk puzzle. Neuromuscular coordination, tissue resilience, pitch mechanics, and recovery all play equally vital roles. Moreover, the study design—averaging across a wide range of pitchers—obscures the fact that individual mechanics can drastically shift torque demands. A sidearm pitcher and an over-the-top thrower of identical size will not experience torque in the same way.

Still, the signal is clear: size amplifies stress. Ignoring that truth risks pushing athletes into a trade-off they cannot afford. Coaches must weigh the benefits of added mass against the measurable increase in joint loading. For some, the torque-to-velocity trade-off will be worth it; for others, it will accelerate the path to injury.

Baseball performance is a constant balancing act between force production and force tolerance. The Slowik et al. (2025) study makes explicit what many have long suspected—that bigger bodies generate bigger stresses. This does not negate the value of strength and size, but it reframes the conversation: weight must be functional, not arbitrary. For developing pitchers, especially those in pursuit of velocity, individualized strategies that consider anthropometrics, mechanics, and workload adaptation will remain the cornerstone of sustainable progress.

References

• Slowik, et al. (2025). Effects of Weight, Height, and Related Parameters on Elbow Varus Torque in Collegiate and Professional Baseball Pitchers. [Details of publication].
  
• Manzi, V., et al. (2021). Intra- versus inter-pitcher comparisons: Associations of ball velocity with throwing-arm kinetics in professional baseball pitchers.
• Gdovin, J., et al. (2025). Impact of an 8-week pitching-only program on arm health and performance.