It’s easy to get caught up in aesthetics when evaluating pitching mechanics. We’re often drawn to what looks clean—over-the-top deliveries, steep arm angles, exaggerated trunk tilt. But what’s efficient for one athlete might not be efficient for another. A recent study (PMID: 39744973) on elite college pitchers challenges some of the assumptions we’ve made about arm slot and how it affects both performance and stress.

Here’s what the researchers found:

In a sample of high-level pitchers averaging 86.3 mph, lower arm slots consistently reduced joint stress without reducing throwing velocity. In other words, dropping the arm slot did not mean sacrificing performance.

Let’s break it down:

➡️ Elbow Varus Torque (a key indicator of UCL stress):
Overhand throwers experienced the highest torque at the elbow (6.7 %BWBH), while sidearm throwers had the lowest (6.0 %BWBH). That’s a statistically significant drop in stress.

➡️ Shoulder Internal Rotation Torque:
Similar pattern. Overhand deliveries generated 6.6 %BWBH, while sidearm pitchers came in at 5.8 %BWBH. Less stress up top too.

➡️ Torque Efficiency:
This one matters most: sidearm pitchers created more velocity per unit of torque—meaning they were more efficient. Their bodies produced the same result with less wear and tear.

➡️ Trunk Positioning Differences:
Overhand pitchers relied on more extreme body positions—greater side bend (-23°) and forward flexion (39°)—compared to sidearm pitchers who showed less lateral tilt (-12°) and were more upright (26°). That extra movement may contribute to the added joint load.

➡️ Velocity?
No significant differences across arm slots. Velocity stayed consistent regardless of how high or low the arm came through (p = 0.668).

What This Means for You

Mechanics are not one-size-fits-all. The takeaway here isn’t that every pitcher should throw sidearm—it’s that arm slot is strongly influenced by posture, not preference. And if you’re not addressing the trunk’s orientation—how the rib cage is positioned, how the scapula is allowed to move freely over it—then you’re not really addressing arm slot at all.

The scapula slides over the rib cage. So if an athlete doesn’t have the control or mobility to organize the trunk well, the arm slot ends up being forced, not functional. That’s where inefficiencies and injury risk creep in.

Pitchers should not be coached to change their arm slot in isolation. The conversation has to start with how the trunk moves and how the scapula interacts with it.

If you’re trying to throw harder and stay healthy, it's not just about where your arm comes through—it’s about how your body puts it there. Lower slots may offer a safer, more efficient path for some athletes, especially when those slots emerge naturally from a well-organized posture.

We don’t chase aesthetics at VeloU—we chase outcomes that scale sustainably.