A 2021 study published in The International Journal of Sports Physical Therapy examined shoulder external rotation and internal rotation strength in 242 minor league baseball players. Researchers Michener and colleagues compared pitchers to position players and looked at differences between athletes from North America and Latin America. Using a hand-held dynamometer, they measured strength on the throwing arm and normalized the values to body weight to account for size differences. What they found challenges some fundamental assumptions about how specialized arm care programs influence shoulder strength, and more importantly, raises questions about what we're getting wrong in North American pitcher development.

What the Study Found

The most striking finding wasn't just that position players demonstrated 14 to 20 percent greater external and internal rotation strength than pitchers on their throwing arm, it was that this gap existed despite pitchers having access to far more specialized arm care programming. Think about that for a second. The athletes we invest the most resources into, the ones doing weighted ball programs and band work and structured throwing plans, had weaker shoulders than the position players who spend most of their time taking ground balls and batting practice. North American position players in particular outperformed their own pitchers in both ER and IR strength, with differences that reached statistical significance at p values less than .001.

But here's where it gets interesting. Latin American pitchers showed 11.8 percent greater external rotation strength and 16.7 percent greater internal rotation strength compared to North American pitchers. This wasn't a small difference that barely reached significance, this was a clinically meaningful gap that persisted even after accounting for body weight. The researchers confirmed that all measurements exceeded minimal detectable change thresholds, meaning these weren't just statistical artifacts but real, observable differences in how strong these athletes were. Even more surprising, North American pitchers showed lower normalized shoulder strength despite having heavier body mass than their Latin American counterparts. The ER to IR ratio, which some theorize contributes to shoulder stability, was generally higher in position players across the board. Latin American position players had a notably higher ratio than their pitcher counterparts, reaching significance at p equals .020. When collapsed across player type though, no significant differences in ER to IR ratios emerged between geographic regions, suggesting that muscular balance might be preserved despite the strength disparities.

Why This Information Is Important

The strength gap between pitchers and position players tells us something uncomfortable about how we approach pitcher development in North America. To be honest, this reminds me of conversations I've had with coaches who assume that more specialized training automatically equals better outcomes. But what if the opposite is true? What if the high velocity and high volume demands unique to pitching are actually creating a training environment that suppresses strength adaptations over time?

Research on muscular fatigue in adolescent pitchers shows that after just 35 pitches, athletes experience measurable losses in hip strength and rotational coordination. The fatigue doesn't start in the arm, it starts in the hips, and when hip rotation and pelvic velocity drop, the torso compensates by disrupting energy transfer and forcing the shoulder and elbow to absorb more stress. This creates a cascade where the very act of pitching at high intensity begins to degrade the physical qualities that protect the arm. Frequent exposure to maximal effort throws likely leads to neuromuscular fatigue that never fully resolves, and when you layer more high intent throwing on top of that fatigue, you're not building strength, you're managing damage.

Position players, in contrast, throw at lower intensities but with much higher frequency. They're playing catch, making throws from the outfield, turning double plays, and these throwing patterns might actually offer a protective training effect. Studies on pitchers who also play catcher show a nearly three times increase in injury risk, but that's not because catching itself is dangerous, it's because the combination of max effort pitching plus high volume positional throwing creates a workload the arm can't recover from. The position player who never pitches though? They're getting volume without the valgus stress and velocity demands that come with trying to throw 95 mph off a mound.

This is where the Latin American pitcher data becomes critical. What are they doing differently that results in shoulders that are 12 to 17 percent stronger than North American pitchers? The most logical explanation is their training culture. Latin American development often emphasizes consistent daily throwing at moderate intensities rather than the American model of throwing hard twice a week with long periods of rest in between. A study of elite Dominican prospects found widespread structural changes in the shoulder and elbow despite the athletes being asymptomatic, which tells us their arms are adapting to high volume throwing from a young age. These aren't injuries, they're adaptations. Their tissue is remodeling in response to consistent mechanical load.

Research on reduced effort pitching shows that even when pitchers dial back to 50 to 75 percent perceived effort, their elbows still absorb 74 to 81 percent of the torque seen at full intensity. This suggests that moderate intensity throwing isn't really "easy" on the arm, it's still providing significant stimulus. But here's the key difference, moderate intensity allows for higher frequency without accumulating the same neuromuscular fatigue that max effort work creates. Studies on velocity loss thresholds in resistance training confirm this principle. High quality, high velocity repetitions drive power adaptations, but excessive velocity loss, meaning training to failure or near failure, degrades explosive output and delays recovery. The same logic applies to throwing. If you're constantly chasing max effort velocity, you're constantly generating fatigue that limits your ability to adapt.

Professional pitchers provide another clue. Research comparing professional to high school pitchers shows that professionals generate more velocity with less relative elbow torque by using greater trunk and pelvis rotation. High school pitchers rely more on the arm, muscling the ball rather than transferring energy efficiently through the kinetic chain. Latin American pitchers may develop similar coordination advantages through years of consistent throwing, building movement patterns that distribute stress more effectively. This would explain why they can generate significant strength gains even while throwing frequently, their mechanics allow them to train the shoulder without overloading it.

Early career workload also plays a role. A retrospective study of Major League Baseball pitchers found that UCL injuries were strongly linked to early season timing and early career workload, with velocity playing a smaller role than often assumed. North American pitchers often face dramatic workload spikes when they transition from high school to college or from college to professional ball, and these spikes happen in systems that prioritize max effort performance over gradual adaptation. Latin American players, many of whom play year round from childhood, may simply have more robust tissue that's been conditioned over a longer timeline.

How Can This Information Be Applied

If you're coaching youth or amateur pitchers, the application here is straightforward but requires a philosophical shift. Stop treating arm care as something separate from throwing. The best arm care is probably throwing itself, but only if it's done at frequencies and intensities that allow adaptation rather than just accumulating fatigue. This doesn't mean abandoning velocity development, it means recognizing that max effort throwing needs to be dosed carefully and supported by higher volumes of moderate intensity work.

Consider what position players are doing. They throw almost every day, but rarely at max effort. Their arms are constantly being loaded, constantly adapting, and as a result they develop stronger shoulders than the pitchers who throw twice a week at 100 percent intent. You can replicate this by having pitchers play catch at longer distances, not to build arm strength in the traditional sense, but to create consistent mechanical load without the valgus stress of pitching off a mound. Research on long toss shows that ball velocity rises steadily with distance, but elbow torque plateaus after 120 feet, meaning you can get throwing volume without proportionally increasing joint stress.

For athletes in structured programs, pay attention to how fatigue is being managed. If your pitcher is losing velocity during a bullpen session or showing signs of mechanical breakdown, that's not just fatigue, that's your window for adaptation closing. Studies show that when velocity loss exceeds certain thresholds, you shift from training power to training fatigue resistance, and those are very different adaptations. Use velocity tracking or even just video analysis to identify when quality drops, and stop the session before you're just grinding through tired reps.

If you're working with athletes who have access to year round throwing, take advantage of it. The Latin American model isn't about throwing harder more often, it's about throwing consistently at intensities that don't require three days of recovery. This could mean more frequent short toss sessions, more playing catch at 90 to 120 feet, more positional throwing drills that emphasize accuracy over velocity. The goal is to keep the arm in a constant state of adaptation rather than cycling between high stress and complete rest.

Finally, recognize that body weight matters. The study showed that North American pitchers had heavier body mass but still demonstrated lower normalized strength. This suggests that simply being bigger doesn't protect you if you're not building the specific strength qualities that resist rotational forces at the shoulder. Incorporate exercises that load the shoulder in rotation, focus on positions that mimic the late cocking phase of throwing, and prioritize movement quality over absolute load. Strength matters, but only if it's accessible during the rapid, ballistic movements that define pitching.

Conclusion

The fact that Latin American pitchers have significantly stronger shoulders than North American pitchers, and that position players across both regions have stronger shoulders than pitchers, should force us to reconsider what we think we know about arm care. Specialized programs aren't inherently better if they're built on a foundation of high intensity, low frequency work that creates more fatigue than adaptation. The athletes who throw most often at moderate intensities, whether they're position players or Latin American pitchers who grew up playing year round, seem to develop more resilient shoulders.

This doesn't mean every pitcher should start throwing seven days a week, it means we need to be far more thoughtful about how we balance intensity, volume, and recovery. The goal isn't to avoid hard throwing, it's to create a training environment where hard throwing is supported by enough moderate intensity work to keep the tissues adapting rather than just breaking down. If we can learn anything from how Latin American players develop, it's that consistency and frequency at manageable intensities might be more valuable than we've given them credit for.

References

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