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A 2024 study published in Sports Health tracked 23 collegiate pitchers using motion analysis throughout a simulated game protocol. Researchers measured whole-body center of mass position, lower-extremity joint angles, velocity, and accuracy to understand how the body's control strategies changed as pitchers accumulated throws. The findings showed that pitchers shifted their center of mass forward and downward while increasing hip and knee flexion as the game progressed. Despite these postural and kinematic changes, pitching velocity and accuracy remained statistically unchanged. The researchers suggested these mechanical shifts should be monitored for injury prevention, yet provided no evidence that joint torque increased, tissue stress elevated, or any actual harm occurred.
As the simulated game progressed, the pitchers' whole-body center of mass shifted significantly forward and downward compared to their initial mechanics. At the same time, both hip flexion angles and knee flexion angles increased significantly. The center of mass also became more variable in all three directions, mediolateral, anteroposterior, and vertical, suggesting the body was exploring different movement solutions as fatigue accumulated. Yet despite these measurable postural and kinematic changes, pitching velocity showed no significant decline. Accuracy also remained statistically unchanged throughout the protocol. The body found a way to keep producing the same output despite the accumulating demand.
To be honest, this reminds me of something we see in other fatigue research. When Johnson and colleagues tracked adolescent pitchers in 2025, they found that pelvic rotation velocity dropped by 2.3 degrees per second with each pitch after just 35 throws, and torso rotation angle decreased by 1.3 degrees at ball release. The hips fatigued first, the torso picked up slack, and energy transfer got disrupted. But the athletes still threw. The system compensated. That's exactly what's happening in this collegiate study, just framed differently. As power begins to dissipate, athletes likely access deeper ranges of motion to generate the force needed. The forward and downward center of mass shift combined with increased hip and knee flexion suggests the torso may be picking up more of the workload as the legs fatigue. This is compensation in real time, and the data suggests it's working.
But here's what keeps coming back to me. The study labels these changes as something to monitor for injury prevention, yet they provide no data on whether joint torque increased, tissue stress elevated, or any actual harm occurred. The pitchers maintained their velocity and accuracy. That tells me the system adapted successfully to the demand. When Yanai and colleagues measured varus strength at the elbow in 2025, they found that nearly half of competitive pitchers don't have enough muscular strength to completely unload the UCL when throwing fastballs. These athletes were operating at 103 percent of their maximum voluntary strength just to keep the ligament partially protected. Yet they pitch. Successfully. Repeatedly. The body doesn't operate in a sterile lab where everything is perfect, it operates under constraint and finds solutions.
The increased center of mass variability could be interpreted as loss of control, or it could be the body exploring different movement solutions to distribute stress. Leafblad and colleagues showed us in 2019 that throwing variability is not only normal but highly individual. When they tracked 60 high school and collegiate pitchers during a structured long toss program, they found that torque variability between athletes was massive, with only 79 percent of pitchers showing acceptable consistency compared to 91 percent for velocity. Movement isn't robotic. It shifts. It adapts. And when we pathologize every deviation from some theoretical optimal pattern, we risk creating fear around something the nervous system is already managing.
We need to be careful about pathologizing normal fatigue responses. The assumption embedded in much of the injury prevention literature is that mechanical change equals increased injury risk. But mechanical change is unavoidable. Expecting pitchers to maintain identical kinematics across 80, 90, 100 pitches is as unrealistic as saying just keep throwing until your arm falls off. Neither extreme serves the athlete.
What this study really shows is that the body has options. When fatigue accumulates, the system doesn't break down immediately, it recalibrates. It finds new movement strategies. It accesses different joint angles. It redistributes load. And if the output remains stable, velocity unchanged, accuracy maintained, then the compensation worked. The question we should be asking isn't whether mechanics change under fatigue, because they will. The question is whether the athlete has the physical preparation and movement options to adapt without breaking down.
This connects directly to how we think about training. Jukic and colleagues analyzed velocity loss thresholds during resistance training in a 2023 meta-analysis and found that while higher fatigue drove hypertrophy, excessive fatigue blunted power output. But critically, they also found that low to moderate velocity loss, between 10 and 25 percent, achieved an optimal balance. The body could adapt without degrading explosive performance. Fatigue wasn't the enemy. Unmanaged or excessive fatigue was. That same principle applies here. If we train athletes to tolerate fatigue, to maintain intent and execution under accumulating demand, then the kinematic changes we see during games aren't red flags. They're proof the system is functioning.
The bigger issue is that we're measuring the wrong things. Without direct measures of tissue load, joint torque, or ligament stress during these fatigued conditions, we're documenting surface-level kinematics and inferring risk. That's guessing. The study acknowledges this implicitly by not making injury claims, but the framing still leans toward concern. If an athlete's elbow varus torque didn't increase, if shoulder internal rotation velocity stayed within normal ranges, if tissue strain didn't escalate, then the kinematic shifts are just the body doing its job.
If the athlete is properly trained and has built the capacity to handle fatigue, these compensations aren't warning signs, they're proof the system is working. That shifts the focus away from trying to prevent all mechanical variation and toward building robust, adaptable athletes who can handle the demands of competition without breaking down.
Practically, this means strength and conditioning programs for pitchers need to emphasize fatigue resistance in the lower body and trunk, not just arm care. When Johnson's adolescent pitchers lost pelvic rotation velocity and torso angle after 35 pitches, the implication was clear. The hips fatigued first. The torso compensated. And if the torso isn't strong enough or coordinated enough to handle that redistribution, the arm pays. Focusing on muscular endurance and power endurance of the lower half, particularly hip extension strength and rotational endurance, may be one of the most underutilized levers we have for keeping pitchers healthy under fatigue.
Training should also include exposures to fatigue that mimic game conditions. Just like Jukic's work showed that controlled velocity loss can drive adaptation without destroying power output, controlled pitch exposures under accumulating fatigue can teach the nervous system how to adapt. The goal isn't to eliminate fatigue. It's to teach the body how to function within it. This might mean finishing bullpen sessions with a cluster of throws after intentional lower-body pre-fatigue. It might mean structuring live at-bats later in a training session when the legs are taxed. It means exposing the system to the conditions it will face and giving it the opportunity to solve problems.
Monitoring should shift from reactive to contextual. Instead of flagging every kinematic change as a potential issue, we need to ask whether the athlete's intent was achieved. Did velocity hold? Did accuracy stay consistent? Did the athlete report feeling in control of their delivery? If yes, then the mechanical shifts are likely adaptive. If no, then we dig deeper. Was it a strength deficit? A coordination issue? A motor control breakdown? The kinematic data becomes useful when paired with performance outcomes and subjective feedback, not in isolation.
This is also where individualization becomes critical. Some athletes will show larger center of mass shifts than others. Some will increase knee flexion more dramatically. Some will maintain tighter variability. None of that tells us who's at higher risk unless we understand the athlete's baseline capacity, their training history, and their tissue tolerance. One pitcher's compensation might be another pitcher's normal movement solution.
The body found a way to keep producing the same output despite accumulating fatigue. That's not a failure of the system. That's the system working. Pitchers shifted their center of mass forward and downward, increased hip and knee flexion, and explored more variable movement options as the game progressed. And they still threw hard. They still hit their spots. The study documented adaptation, not breakdown.
We're at risk of pathologizing normal responses to fatigue. Mechanics change. They always have. They always will. The critical variable isn't whether change occurs, it's whether the athlete has the physical preparation, movement options, and neuromuscular capacity to adapt without structural compromise. If we focus on building robust, fatigue-resistant athletes rather than chasing some unattainable mechanical ideal, we're far more likely to keep them healthy and performing at a high level.
Do you think monitoring kinematic changes during a game provides actionable information, or are we just documenting what the body is already handling on its own?
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