For decades, curveballs have been vilified as the pitch most likely to blow out a young pitcher’s elbow. But new data from motion capture analysis of professional pitchers flips that narrative on its head. This study didn’t rely on assumptions—it tracked fastballs, curveballs, sliders, and change-ups to measure three of the most critical metrics for elbow health: peak varus torque, cumulative joint load, and loading rate. The results demand a more nuanced approach to pitch selection, especially for coaches working with developing arms.

What the Study Found

A team of researchers evaluated 31 professional pitchers using high-speed motion capture (480 Hz) and TrackMan data during full bullpen sessions. They measured medial elbow stress across four pitch types—fastball, slider, curveball, and change-up—and analyzed:

• Peak elbow varus torque: the highest joint stress during delivery
  
  
• Cumulative torque: total joint load across multiple throws
  
  
• Loading rate: how quickly that stress is applied
  
  
• Spin rate: to assess its relationship with torque
  
  

Here’s what they discovered:

• Fastballs generated the highest peak elbow varus torque [90.1 N·m], loading rate, and cumulative joint stress (p < .001).
  
  
• Sliders produced similar peak torque to curveballs (~87.7 N·m), but with significantly higher loading rates.
  
  
• Curveballs had the lowest cumulative elbow torque of all pitch types—contrary to longstanding fears.
  
  
• Change-ups, despite lower peak torque [81.3 N·m], had surprisingly high cumulative torque due to usage frequency and effort profiles.
  
  
• Spin rate showed no significant correlation with torque across any pitch type, suggesting it’s not a reliable predictor of joint stress.
  
  

Why This Matters

For years, pitch type instruction has been shaped by unvalidated fears—particularly around curveballs. Yet this motion capture analysis shows that fastballs are the most stressful pitch type when examining raw joint load and loading rate. Curveballs, when thrown with professional-level mechanics, generated the lowest cumulative elbow stress of all pitches analyzed.

But that doesn’t mean the curveball is inherently “safe.” It’s not the pitch type in isolation—it’s how the body handles it.

• Fastballs create high peak stress and are thrown most frequently.
  
  
• Change-ups, while often viewed as “easy” pitches, quietly accumulate high joint load over time.
  
  
• Sliders, with their explosive movement and late break, deliver torque rapidly—raising red flags for loading rate.
  
  
• Curveballs, in contrast, distribute force more gradually and result in lower joint wear in this cohort.
  
  

These are elite professionals with refined movement patterns. They are efficient in ways that youth and amateur pitchers are not. So while this study supports moving away from curveball fear-mongering, it doesn’t mean we should rush to teach it universally. We should instead focus on developing efficient mechanics first—because stress doesn’t just come from the pitch; it comes from how the pitch is delivered.

How We Apply This at VeloU

At VeloU, we’ve long emphasized that pitch type is secondary to movement quality. This study affirms that belief. Our athletes don’t earn the right to manipulate spin or chase pitch shapes until they’ve demonstrated mechanical consistency under load.

This research also reframes how we think about cumulative joint stress. We don’t evaluate pitch design decisions in isolation—we monitor frequency, velocity, and mechanical efficiency. A fastball might be your bread and butter, but if it’s packing the highest torque and you’re throwing it 70% of the time, your joint stress profile looks very different than the guy with a balanced arsenal.

Curveballs may not be the villain we once thought. But no pitch is safe if thrown with inefficient mechanics. And no pitch is dangerous when delivered with precision, control, and preparedness.

Reference

Mihata, T., McGarry, M. H., Kinoshita, M., Kinoshita, M., Lee, T. Q., & Tokish, J. M. (2024). Pitch Type Is Associated With Elbow Torque and Loading Rate but Not Spin Rate in Professional Baseball Pitchers. The American Journal of Sports Medicine. https://doi.org/10.1177/03635465241256249