We often hear debates about what matters most for velocity: strength or mobility? This new study offers a clear answer: rotational strength at the shoulder is a primary driver of throwing velocity, while passive range of motion (ROM) might not matter nearly as much as we think.

Researchers examined shoulder strength and ROM in collegiate pitchers, then analyzed how these variables correlated with biomechanics and fastball velocity. What they found reinforces what we see in the weight room and on the mound: strong shoulders throw harder, flexible ones don’t necessarily.

What the Study Found

• Isometric internal and external rotation strength was strongly correlated with pitch velocity (r = 0.66–0.76, p < 0.05).
  
  
• External rotation strength at 90°/s and 180°/s showed the strongest relationships with velocity (r = 0.69–0.77, p < 0.05).
  
  
• Greater rotational strength also predicted higher shoulder compressive forces, indicating greater kinetic output capacity (r = 0.61–0.70, p < 0.05).
  
  
• No significant correlation was found between shoulder ROM (external or internal) and velocity or kinetic variables.
  
  
• Strength data was gathered isometrically and isokinetically, while pitching biomechanics were captured using a validated 3D motion capture system.
  
  

Why This Matters

This study puts hard data behind what elite trainers and coaches have known intuitively: powerful shoulders generate powerful results. While mobility matters for safe mechanics and movement quality, it doesn’t appear to meaningfully impact pitch velocity or force output in trained athletes, at least not in isolated measurements.

What stands out most is the high correlation between external rotation strength and velocity. This makes sense functionally, as the shoulder must withstand extreme forces in external rotation before transitioning rapidly into internal rotation during the throw. Athletes with greater ER strength are better equipped to absorb and redirect that energy into forward motion — a prerequisite for high velocity.

It’s also telling that strength, not ROM, correlated with shoulder compressive force — the force driving the humeral head into the socket. This indicates that stronger athletes not only throw harder but also do so by producing higher internal joint forces, meaning they are both more explosive and more structurally demanding.

Still, this was a small cohort [n = 13] and included only uninjured collegiate pitchers. We don’t know if the same trends would hold across higher velocity ranges, injury histories, or over the course of a season. Also, ROM was only captured at baseline — changes over time were not tracked, which limits insight into how mobility fluctuations influence long-term performance or health.

How We Apply This at VeloU

At VeloU, this study confirms what our in-house assessments already suggest: rotational strength is one of the clearest predictors of pitching performance.

That’s why our programs prioritize both isometric and dynamic rotational loading through specialized protocols — including resisted band work, isokinetic shoulder work, and controlled tempo eccentrics to build force and rate of force development in both IR and ER. These adaptations don’t just support velocity — they also improve an athlete’s ability to decelerate and tolerate joint stress.

While we always screen for shoulder ROM, we never assume that “more is better.” Instead, we focus on functional mobility within the context of strength. If an athlete is extremely mobile but underpowered, that’s a performance and durability risk. If they’re tight but strong — we determine whether that stiffness is adaptive or problematic based on mechanics and tissue quality.

This study supports a core belief in our model: velocity doesn’t come from flexibility — it comes from force. Mobility is a tool, not the driver. And in high-performing pitchers, strength at the right joints, through the right ranges, is what separates the good from the elite.

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

Aune, K. T., Laughlin, W. A., Padua, D. A., Fleisig, G. S., & Oliver, G. D. (2024). Relationships among shoulder rotational strength, range of motion, pitching kinetics, and pitch velocity in collegiate baseball pitchers. Journal of Orthopaedic & Sports Physical Therapy, 54(5), 1–27. https://doi.org/10.1016/j.jospt.2024.03.010