We’ve all heard the mantra: throw harder, stress more. But what if that’s not universally true?

This study looked at 91 professional pitchers and compared how throwing velocity impacts arm stress in two different ways: across pitchers (inter-pitcher) and within the same pitcher (intra-pitcher). The takeaway was simple — throwing hard doesn’t automatically mean a pitcher is placing more stress on the arm than someone throwing slower. However, when a pitcher throws harder than they usually do, stress goes up fast.

What the Study Found

• Across pitchers, ball velocity only weakly predicted:
  
  
  
  • Shoulder distraction force (R² = 0.228)
    
    
  • Elbow distraction force (R² = 0.175)
    
    
• Within a pitcher, velocity strongly correlated with nearly every major arm stress metric:
  
  
  
  • Shoulder internal rotation torque
    
    
  • Shoulder horizontal adduction torque
    
    
  • Shoulder superior and anterior forces
    
    
  • Elbow varus torque, medial, anterior, and flexion forces
    
    
  • Elbow and shoulder distraction forces
    
    
  • All with R² > 0.85 (p < 0.001)
    
    
• The only variable that didn’t show a statistically significant intra-pitcher correlation was shoulder adduction torque (R² = 0.868, p = 0.052), likely due to variance in shoulder positioning strategies.
  
  

This means that while some guys may throw 95 with lower torque than others throwing 90, once you start pushing your upper limits, your internal joint forces start climbing sharply.

Why This Matters

In the pursuit of velocity, athletes often look sideways — comparing themselves to peers, pros, or others with similar build or mechanics. But this study makes it clear: your stress response is personal.

Throwing harder than your norm almost always means greater elbow and shoulder torque — regardless of whether you’re built like deGrom or dominate with deception.

So, rather than comparing radar gun numbers, athletes and coaches should be tracking intra-athlete load responses. What happens to your arm when you throw 87 vs. 91? How do your RC strength metrics or force outputs shift over time? Are you recovering fully between high-output days?

The problem isn’t throwing hard — it’s throwing hard without knowing how your body handles it.

How We Apply This at VeloU

At VeloU, this reinforces our belief that throwing programs should be individualized based on how each athlete’s body responds to stress.

That’s why we collect frequent data points on rotational strength, range of motion, force output, recovery metrics, and velocity. It’s not enough to track velocity in isolation. We want to know how much torque your body produces at each velocity band and whether that stress is trending up or down across the season.

More importantly, we build in safeguards — downregulation days, reduced intent sessions, targeted RC loading, and force plate monitoring — to catch when an athlete’s threshold is being exceeded.

Because this study makes it clear: your stress rises when your velo climbs. That rise might not show up in someone else’s data, but it’ll show up in yours. And if you’re not monitoring that climb, it’s easy to go over the edge.

This article is part of Applied Baseball Science by Dr. Nicholas Serio, where we break down the biomechanics, performance science, and injury research shaping the modern game. Powered by VeloU (Velo University) — where research meets real-world baseball.

Reference

Dai, B., Butler, R. J., Garrett, W. E., & Padua, D. A. (2024). Ball velocity is a weak predictor of throwing arm kinetics in professional baseball pitchers. The American Journal of Sports Medicine, 52(6), 1568–1576. https://doi.org/10.1177/03635465241240482

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