Introduction

There's a common assumption in baseball training that if you want to throw harder, you need a stronger arm. It sounds logical enough. But how much does shoulder strength actually contribute to throwing velocity, and where does that relationship start to level off? A 2024 study by Job and colleagues examined whether shoulder rotator strength and rate of force development were linked to throwing velocity in high school and college pitchers. The findings offer helpful context for how shoulder strength relates to velocity, but also where its impact may plateau. Maximal isometric force of the shoulder internal and external rotators showed a modest positive association with throwing velocity, with each 30 N increase in strength adding approximately 1 to 1.6 mph. But rate of force development, how quickly that force was produced, showed no clear link to velocity and was excluded from all predictive models. The takeaway isn't that strength doesn't matter. It's that strength is one lever, not the lever.

What the Study Found

The researchers tested high school and collegiate pitchers on both maximal isometric force (Fmax) and rate of force development (RFD) for shoulder internal and external rotation, then compared those measures to throwing velocity. One of the more surprising findings was that high school and collegiate pitchers threw at nearly identical velocities (36.3 vs 36.4 m/s), despite differences in age and forearm length. This suggests that by the time pitchers reach high school, something other than arm strength is driving the velocity differences we see at higher levels.

Peak force from shoulder internal rotation and external rotation was modestly associated with throwing velocity. Each 30 N increase in IR strength corresponded to approximately a 1 mph gain, while a 30 N increase in ER strength predicted a velocity increase of about 1.6 mph. These are real gains, and in competitive environments where small differences matter, they're worth pursuing. But the relationship was modest, not dominant.

Rate of force development showed no meaningful connection to throwing velocity and was excluded from all predictive models. This may be due to how RFD was tested, under static, isometric conditions that don't fully reflect the dynamic nature of a throwing motion. Still, the finding is notable. In a sport obsessed with explosiveness, the ability to produce force quickly didn't predict who threw hardest.

The study also found that internal and external rotation strength were strongly related to each other (r = 0.63-0.71), meaning pitchers with strong accelerators also had strong decelerators. This reinforces the idea that balanced rotator development matters for both performance and durability.

Why This Information Is Important

This study provides important context, but it becomes even more meaningful when placed alongside other research on what actually drives throwing velocity. A 2018 study comparing professional and high school pitchers found that professionals generate more velocity with less relative elbow torque by using greater trunk and pelvis rotation. High school pitchers who threw harder in that study also produced the highest elbow torque relative to body size. The professionals had learned to time and sequence their hips and trunk so the arm simply transferred energy rather than creating it.

Research on pelvic-trunk coordination reinforces this point. A 2025 study found that greater separation between pelvic and trunk rotation from foot contact to maximum external rotation was positively correlated with velocity (r = 0.74). That's a much stronger relationship than the modest correlations found between shoulder strength and velocity.

The question of how much strength is enough has been addressed in other sports. A 2025 study on trained football players found that sprint performance plateaued once athletes reached isometric mid-thigh pull strength of 2.0 times bodyweight. Beyond that threshold, additional strength no longer predicted faster times. The same principle likely applies to pitching. There's a foundation of strength that supports performance, but past a certain point, the returns diminish.

Research on adolescent pitchers adds nuance. A 2024 study found that oblique strength was positively correlated with pelvis and trunk rotation velocity without increases in joint torque. But oblique strength was not directly associated with ball velocity in this younger group. The authors suggested these adaptations may be quiet but foundational, setting up efficient movement patterns that eventually translate to velocity as athletes mature.

Lower body contribution matters too. A 2025 study on youth pitchers found that drive leg forces transfer linear power through the kinetic chain while stride leg forces create rotational power. Force production matters, but timing of how that force is applied matters more. A strong drive leg without stride leg braking leads to poor transfer.

Training research supports an integrated approach. A 2024 study comparing compound training (resistance plus plyometrics), plyometric training alone, and kettlebell training alone found that the compound group produced 5 to 6 times greater velocity gains over just four weeks. Integrated programming outperformed isolated strength work.

How This Information Can Be Applied

Building rotational strength can move the needle, especially for developing athletes. A 1 to 1.6 mph gain for every 30 N increase in shoulder strength is meaningful when compounded over time. But it's not the whole answer. Maximal force serves as a foundation that supports other qualities like sequencing, timing, and transfer through the kinetic chain.

For athletes still developing, strength work isn't just injury prevention. It's a small but meaningful contributor to the pursuit of velocity. Building balanced rotator strength creates resilience and supports high-velocity demands. But that strength needs to be integrated into programming that also addresses how force is transferred from the ground up.

For more advanced athletes who already have a solid strength foundation, the emphasis should shift toward coordination, sequencing, and timing of energy transfer. The research on strength thresholds suggests that once foundational levels are met, the limiting factor shifts to skill and movement efficiency rather than raw force.

Conclusion

Shoulder strength has a real but modest relationship with throwing velocity. Stronger internal and external rotators were linked to higher velocity, but the gains were small, and rate of force development showed no predictive value. The bigger story across the research is that velocity comes from coordination, sequencing, and efficient transfer of energy through the kinetic chain. The arm receives energy; it doesn't create it. Strength serves as a foundation to support those qualities, not as a replacement for them.

References

1. Job TDW, Cross MR, Cronin JB. Relationship of shoulder internal and external rotation peak force and rate of force development to throwing velocity in high school and collegiate pitchers. The Journal of Biomechanics. 2024.
2. Luera MJ, Dowling B, Magrini MA, et al. Role of Rotational Kinematics in Minimizing Elbow Varus Torques for Professional Versus High School Pitchers. The Orthopaedic Journal of Sports Medicine. 2018.
3. Vial S, Scanlan M, Beranek P, et al. How Strong Is Strong Enough? The Journal of Strength and Conditioning. 2025.
4. Eilen HT, Kokott W, Dziuk C, Cross JA. Relationship of Abdominal Oblique Strength on Biomechanics in Adolescent Baseball Pitchers. The Journal of Athletic Training. 2024.
5. Kim J, Jaber H, Yim J. Comparison of the Effects of Compound Training, Plyometric Exercises, and Kettlebell Exercises. The International Medical Journal of Experimental & Clinical Research. 2024.
6. Glover MA, Mylott JA, Gaba A, et al. The Impact of Drive Leg Impulse and Slope on Throwing Velocity. The Journal of Biomechanics. 2025.
7. Wang SM, Chen SH, Chen HY, et al. Pelvic Control and Pelvic-Trunk Coordination as Key Determinants of Pitching Velocity. The Orthopaedic Journal of Sports Medicine. 2025.