In nearly every return-to-throw or long-toss program, athletes are asked to throw at “50%” or “75% effort” to protect healing tissues and gradually reintroduce load.

But what if those percentages are a myth?

This study evaluated whether pitchers can accurately regulate intensity based on feel alone. Using radar guns and wearable sensors, researchers analyzed velocity and joint loading across different “effort levels.” The results? A major disconnect between perceived effort and biomechanical reality — and one that could undermine the safety of most rehab protocols.

What the Study Found

• Effort mismatch: A 25% reduction in perceived effort only produced a 7% decrease in elbow varus torque and an 11% drop in ball velocity.
  
  
• False safety: At 50% effort, pitchers still generated 86% of max torque and 78% of max velocity.
  
  
• Consistency, not accuracy: Pitchers were consistent in their mechanics (intrathrower reliability ICC > 0.75), but consistently overshot intended effort levels.
  
  
• No mechanical change: Arm slot, shoulder rotation, and elbow flexion angles remained similar across all effort levels.
  
  
• Flat-ground ≠ low stress: Even without a mound or crow hop, joint stress levels remained surprisingly high.
  
  

In short, what felt like “half effort” was still producing throws that looked — and stressed the arm — more like 80-90%.

Why This Matters

Return-to-throw programs often rely on subjective cues like “light effort” or “easy throws.” But this study shows that self-assessed effort is not a valid proxy for joint loading. That presents a serious problem when dealing with:

• UCL rehab protocols
  
  
• Early phase return-to-throw progressions
  
  
• Volume and intensity ramp-ups post-injury
  
  

Even well-intentioned pitchers — particularly younger ones — cannot accurately judge effort in terms of torque or velocity. That makes the reliance on internal scales of exertion both inaccurate and risky.

This doesn’t just apply to injury settings. It’s also relevant for pitch design sessions, recovery days, and in-season workload management. If your athlete says, “Coach, I’m just playing light catch today,” and it’s 86% of their max torque — that’s not light.

How We Apply This at VeloU

We’ve long been cautious of subjective effort designations, especially during early-stage rehab. Instead, we rely on a layered approach that includes:

• Radar guns to validate actual velocity against baseline metrics
  
  
• Wearable tech like Pocket Radar and motusBASEBALL to track torque and mechanics
  
  
• External pacing cues (metronomes, constraints, etc.) to shape movement quality
  
  
• Video overlay to analyze arm slot and posture deviations across intensities
  
  

When implementing return-to-throw programs, we never assume an athlete’s “50% effort” is biomechanically safe. If we don’t have access to objective data in a session, we use strict positional constraints to ensure joint loading stays manageable.

This study reinforces what we’ve seen on the floor: perceived effort is not enough. In rehab, small margins matter. Misjudging them could delay recovery — or worse, re-injure the athlete.

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

Wasser, J. G., Dowling, B., Serrano, M., Taber, C. B., & Oliver, G. D. (2024). Baseball pitchers’ perceived effort does not reflect joint loading during flat-ground long-toss. Orthopaedic Journal of Sports Medicine, 12(4), 23259671241248983. https://doi.org/10.1177/23259671241248983