Baseball Biomechanics
Biomechanics — the study of human motion and forces — can help baseball players improve almost all aspects of their game. From the training of proper pitch mechanics to the biomechanical analysis of a baseball swing, applying research from this field of sports science can help you generate more power, increase pitch speed, and mitigate risk of injury.
Major league teams increasingly recognize the power of biomechanics in refining their pitching rosters. Current technology allows performance teams to study a pitcher’s movements in great detail and, using that data, help players fine-tune their movements to maximize efficiency, mitigate joint stress and muscle strain, and pitch faster over longer periods of time.
Mark Murphy, DPT, Mass General Brigham Applied Sport Science & Performance Lead, and Beth Wilcox, PhD, a Mass General Brigham research scientist, describe how biomechanics can directly benefit players and answer frequently asked questions about the field.
How is biomechanics used in baseball?
Sports biomechanics is the study of the physics of human movement and how it applies to sports performance. In modern athletic settings, biomechanical analysis includes everything from a coach observing a player's movement patterns to identify technical errors to highly detailed evaluations using advanced motion capture technology.
Biomechanical analyses in baseball aim to help players identify movement patterns or inefficiencies in their technique that may prevent them from achieving peak performance or may put them at an increased risk of injury. For example, a hitter may undergo a biomechanical analysis of their swing using multiple high-speed cameras to watch the swing in slow motion from all angles. They might also wear sensors to analyze the position of their body throughout the swing or to calculate the power they generate through the bat.
At its best, biomechanical analysis provides baseball players with reliable, quantitative data about their performance that can help them focus their training, address weaknesses, and mitigate injury through improved technique and targeted strengthening programs.
Working with a performance team at a facility like the Mass General Brigham Center for Sports Performance and Research gives you access to the biomechanical technology and expertise needed to get the most out of your training and gain a competitive advantage.
Baseball pitching mechanics
Despite the emphasis we may naturally place on the throwing arm, pitching a baseball is a whole-body effort that starts in the legs and hips. As a result, the biomechanics of throwing a baseball are complex:
The wind-up before the pitch loads the player's body like a spring by moving the center of gravity over the back leg.
As the body moves forward again, the back leg pushes to generate force through the body.
The front (lead) leg blocks the body’s forward momentum and helps transfer that force up through the pitching arm.
Biomechanical analysis of a baseball pitch can reveal weak links in this chain of movement to help the player produce a faster pitch. With the right equipment, it's even possible to look specifically at the biomechanics of the elbow during baseball pitching to estimate the forces acting on it during the cocking and deceleration phases, where the greatest forces are produced at the elbow.
Pitching is a full body activity. There’s just as much emphasis on the trunk, pelvis, and legs as there is on the elbow and shoulder. The kinetics (the forces that affect motion) and kinematics (the motion itself) on the elbow and shoulder are heavily influenced by the kinetics and kinematics of the entire body during pitching.
“This information can be used to inform a personalized training program to ensure we are targeting identified insufficiencies in strength, mobility, or stability,” Murphy adds.
Baseball swing biomechanics
The biomechanics of hitting a baseball involve the full-body motion of the batter, starting with loading the back leg and then driving force through the body to the bat.
“In the baseball world, ‘swing efficiency’ is the average bat speed relative to peak hand speed during a swing,” Wilcox explains. “In other words, it tells a hitter how well they are turning their hand speed into bat speed, with a higher score being more ‘efficient.’”
Studying the biomechanics of a baseball swing can reveal factors that negatively impact swing mechanics, allowing teams and coaches to create individualized training plans to address each batter's specific swing.
FAQs about the biomechanics of baseball
Do baseball pitchers improve mechanics after biomechanical evaluations?
Studies show that biomechanical evaluations are effective in improving baseball pitching biomechanics. For example, a long-term study by the American Sports Medicine Institute (ASMI) showed that, among pitchers evaluated twice, half of all the technical flaws discovered at the first evaluation were corrected by the second one.
How much shoulder external rotation does a pitcher need?
The Clinician’s Guide to Baseball Pitching Biomechanics suggests certain degrees of external rotation and joint angles that may help athletes increase performance and reduce risk of injury. However, Murphy and Wilcox emphasize that there is no single ideal number to target.
“Just like runners, every pitcher has a slightly different optimal movement path, driven by their structural and functional individualities,” Wilcox says. Performance teams analyze each pitcher individually and make recommendations based on their unique specifications.
Which baseball pitch puts the most stress on the elbow?
According to a study published in Arthroscopy, higher pitch velocity is associated with greater elbow stress, making fastballs the most stressful pitch for the elbow.
In general, increased forces for the same output could be associated with increased injury risk. In pitching terms, increasing forces about the elbow and shoulder at the same speed may put a pitcher at risk of injury.
The goal is to decrease the shoulder rotation moment and elbow varus moment (an internal moment that stabilizes the medial elbow during the cocking phase of the pitch), but still achieve the same velocity or greater. An athlete could potentially achieve this by not only strengthening their throwing arm but addressing their whole body strength, including the trunk, pelvis, and legs, as well as their kinematic sequencing.
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