Pitching Smart: The Health Science Behind Modern MLB Pitching

Part 1 of a 4 part series

Decades ago, MLB pitchers were celebrated for their ability to throw deep into games, often exceeding 120 pitches without a second thought. Once a group of workhorses, pitchers are now seen as fragile thoroughbreds: carefully managed to minimize the risk of injury. While many fans yearn for the days of old, front offices and coaches have fully embraced a scientific approach combining biomechanics and sabermetrics to protect the sport’s most valuable arms. This shift in ideology, though often contentious among fans, is redefining what it means to “pitch smart” in the major leagues.

Front offices in Major League Baseball face a crucial dilemma: Should they maximize the use of their pitchers at the risk of long-term, career-shortening injuries, or should they limit their playing time to improve longevity and sustained health? Decisions in line with the modern approach to managing pitcher workloads have led to controversial, anger-inducing decisions. Most recently, Paul Skenes of the Pittsburgh Pirates struck out 11 Braves in 7 innings pitched, all in just 99 pitches. Fans were outraged when Skenes was pulled from the game despite his active no-hitter, a move attributed to an overreliance on analytics making coaches more concerned to leave their pitchers in the game.

This strategy prioritizes preventing a buildup of microtrauma to pitcher’s muscle tissue, which reliably escalates to severe injuries like UCL tears, which require Tommy John surgery, sidelining pitchers for more than a year. The trade-off for this approach is worthwhile: The longevity of a pitcher’s career holds more significance than any accolade earned in an individual game. While sabermetrics often limit pitcher workloads, it also gives coaches insight as to when a pitcher can safely push their limits, a true balance of health and performance. 

Pitching Biomechanics

Pitching a baseball is a complex biomechanical action involving precise coordination of the entire body and tremendous stress on the arm and shoulder. The entire kinematic sequence can be broken down into several phases, each accompanied by unique mechanical demands. 

Kinematic Sequence

The pitching motion begins with the windup; the pitcher generates minimal stress while preparing to throw. As they enter the stride phase, they build momentum, positioning their bodies to deliver the baseball. Next is the arm cocking phase, where the pitcher’s shoulder reaches its maximum external rotation, placing considerable stress on the shoulder and elbow joints. In the arm acceleration phase, the torque and kinetic force from the previous stages used to move the pitching arm forward rapidly, generating even higher forces on the elbow and shoulder. The most stress in this process is called elbow valgus stress. All of these forces have to go somewhere after a pitch is thrown. A pitcher’s shoulder undergoes significant eccentric loading to slow down the arm. Finally, the follow-through phase helps dissipate the remaining forces to reduce injury risk. 

Forces and Stresses

Pitching is an occupation that puts the body under extreme forces. A pitcher’s shoulder, especially in today’s environment where throwing harder = throwing better, undergoes external rotation torques that can exceed 50 Nm and internal rotation velocities surpassing 7000 degrees per second. Even with proper mechanics, these forces create a high risk for injury if not managed properly. Ligaments and muscles involved in pitching, such as the ulnar collateral ligament (UCL) in the elbow and the rotator cuff muscles in the shoulder, are relatively small compared to the forces they endure. The UCL, for instance, is only a few millimeters thick but must withstand the 64 Nm (Newton-meters) of torque while pitching. The rotator cuff muscles, small when compared to major muscle groups, bear significant stress during the rapid acceleration and deceleration of the pitching motion. 

Muscle Activation

The rotator cuff muscles, while not as prominent as the larger muscles in the legs or back, play a crucial role in stabilizing the shoulder. They experience high activation during the pitching motion, especially during arm cocking and deceleration phases. The scapular stabilizers are also vital, ensuring efficient force transfer from the lower body to the arm and helping to mitigate the risk of injury by maintaining proper shoulder mechanics. 

Pitching Injuries 

Pitching places immense physical demands on a pitcher’s arm, leading to various injuries, particularly in the elbow and shoulder. According to the article "Biomechanics of Baseball Pitching: Implications for Performance and Injury," several common injuries are highlighted, along with their implications on a pitcher's career and recovery times.

Elbow Injuries:

• Ulnar Collateral Ligament (UCL) Injuries: These are due to high valgus stress on the elbow, particularly during the arm-cocking and acceleration phases. UCL injuries often require Tommy John surgery.

• Recovery Time: Recovery typically takes 12-18 months, impacting a pitcher’s career by causing significant time away from the game and potential changes in pitching mechanics post-recovery.

• Osteochondritis Dissecans (OCD): Repetitive stress causes small fragments of bone and cartilage to detach from the elbow joint.

• Symptoms: Pain, swelling, and loss of motion in the elbow.

• Recovery Time: May require both non-surgical and surgical interventions, with extended time off for healing and rehabilitation.

Shoulder Injuries:

• Rotator Cuff Tears: Caused by repetitive stress, especially during the deceleration phase.

• Labral Tears: Result from extreme rotational forces.

• Recovery Time: Recovery for these injuries can take 6-12 months, with long rehabilitation periods essential for restoring strength and function.

Other Injuries:

• Groin and Abdominal Strains: Occur due to the dynamic rotational movements.

• Knee and Back Soreness: Often result from improper mechanics or overuse.

Kinematic and Kinetic Parameters:

• The study identified specific kinematic parameters (e.g., shoulder abduction, horizontal adduction) at the instant of foot contact that are associated with increased kinetics at the elbow and shoulder.

• Timing of shoulder external rotation, pelvis rotation, and upper trunk rotation significantly influences joint stress and ball velocity.

Effects of Fatigue:

• Fatigue does not significantly alter kinetic values but increases arm pain.

• As pitchers fatigue, they tend to rely more on their arms rather than their lower bodies, increasing injury risk.

Development from Youth to Adult:

• Proper mechanics need to be taught early, as variability in mechanics decreases with development.

• Increased kinetics are observed as pitchers mature, emphasizing the need for proper training and conditioning from a young age.

Implications on Career

Injuries have profound implications on a pitcher's career, affecting both performance and longevity:

• Performance Decline: Injuries often result in decreased performance due to loss of strength, flexibility, and proper mechanics. Pitchers may struggle to regain their pre-injury form, and even minor adjustments in mechanics can lead to further injuries or reduced effectiveness.

• Career Longevity: Frequent injuries or prolonged recovery periods can significantly shorten a pitcher's career. Proper rehabilitation is essential for a successful return to the mound, but the mental and physical toll can be substantial.

Recovery and Time Off

The recovery process for pitching injuries typically involves:

• Surgery: Required for severe injuries such as UCL tears or significant rotator cuff damage.

• Rehabilitation: Structured programs focus on restoring strength, flexibility, and mechanics.

• Extended Time Off: Recovery periods range from several months to over a year, leading to loss of competitive edge and psychological impacts on confidence and performance.

Understanding these injuries and their implications underscores the importance of proper biomechanics, conditioning, and cautious workload management to ensure pitchers perform at their best while minimizing injury risks.

the complex biomechanics of pitching in Major League Baseball highlight the significant physical stresses placed on pitchers' arms and shoulders. Understanding these stresses and the common injuries they cause, such as UCL tears, rotator cuff injuries, and osteochondritis dissecans, is crucial for developing strategies to enhance performance and prevent injuries. As modern baseball continues to evolve, integrating scientific insights into pitcher management becomes increasingly important. The next part of this series will delve into the role of analytics in pitcher management, exploring how data-driven approaches are transforming the game.