We often talk about the lower half, rotational power, and sequencing as the drivers of velocity — but the last thing to touch the baseball still matters. A lot.

A new study using a sensor-embedded ball reveals that the fingers — especially the index and middle — don’t just guide direction, they shape both velocity and spin. Researchers from Japan measured finger strength, force development, and anatomy to examine how they influence fastball characteristics in trained college pitchers.

And the data is clear: finger output directly impacts performance.

What the Study Found

• Middle finger force output significantly correlated with both higher fastball velocity and spin rate.
  
  
• Rate of force development (RFD) in the index and middle fingers also showed strong positive associations with both performance metrics.
  
  
• Pinch strength, specifically 2-point (thumb + index/middle) and 3-point (thumb + index + middle), was correlated with faster fastballs.
  
  
• Greater discrepancy in index vs. middle finger length was linked to higher spin rates and velocity — suggesting anatomical variation plays a role.
  
  
• All data was collected using a validated sensor-embedded baseball to capture real-time force during release.
  
  

Why This Matters

Most training programs overlook the final link in the kinetic chain — the hand. This study emphasizes that force doesn’t just have to be generated — it has to be delivered. And the fingers are the last place that happens.

What’s especially noteworthy is the role of rate of force development. The ability to rapidly apply force in a short time window (i.e., milliseconds before release) appears just as important as peak strength. In other words, it’s not just how strong your grip is — it’s how fast you can use it.

The fact that middle finger force mattered more than index also fits with what we know about pitch spin generation. Since the middle finger often acts as the final point of contact on the baseball, its role in shaping spin axis and rate is critical.

While the small sample size (n = 21) and focus on only four-seam fastballs limit generalizability, the findings build a compelling case for including finger-specific strength and power work in pitching development programs.

How We Apply This at VeloU

At VeloU, we already emphasize forearm and grip strength, but this study adds deeper validation for our targeted hand and finger training protocols.

We program isometric holds like plate pinches using just the index, middle finger, and thumb to train sustained output. For concentric work, we use banded finger flexion to build speed and control in force application. And for eccentric control, we implement finger extension resistance to develop deceleration ability — a key for healthy high-speed release.

We also consider anatomical variance. Pitchers with longer middle fingers or noticeable index/middle discrepancies often demonstrate more natural spin efficiency. Rather than “fixing” this, we train to support their strengths.

Ultimately, this study confirms what we already see on force plates and high-speed video: pitching is a hand-driven skill, and finger function might be the hidden lever many athletes ignore.

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

Seki, T., Inokuchi, S., Takeuchi, T., Omoto, S., Okamoto, K., & Nakazato, K. (2024). The relationship between finger kinetics and fastball pitch characteristics in baseball pitchers. International Journal of Sports Physiology and Performance, 19(5), 630–637. https://doi.org/10.1123/ijspp.2023-0359