Pitching Biomechanics and Youth Baseball Players

J. T. Davis and his colleagues did a descriptive laboratory study on the effects of pitching mechanics on the upper extremity in youth baseball pitchers. The participants were 169 pitchers from youth and high school baseball leagues that had no history of upper extremity injuries. 27 left-handed and 142 right-handed youth baseball players participated in the study. The young pitcher group (ages 9-13) consisted of 86 pitchers, and the adolescent group (ages 14-18) consisted of 83 pitchers. The purpose of creating the two groups was to compare results between an amateur group and a more experienced or developed group of pitchers.

An indoor pitching mound was assembled for the participants to perform their task. A net was set up 25 feet away with a target strike zone that was 33 inches about the ground. Five feet behind the net, a speed gun was placed in order to obtain the velocity of each pitch. Eight 240-Hz cameras were placed around the mound for motion analysis. Two high-speed cameras (250 frames per second) were used for video analysis.

One was placed at home plate, and the other was placed facing the frontal view of the pitcher (first base for left-handed pitchers and third base for right-handed pitchers). A set of reflective markers were placed on each player’s hip, knee, ankle, shoulder, elbow, and wrist.

Each pitcher was allowed to stretch and throw practice pitches before the analysis of the test pitches began. Five pitches were thrown, and the pitch that was closest to the strike zone was used for a final analysis.

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The best pitch was chosen by 3 observers. Five biomechanical parameters of pitching were used to analyze the best pitch for each player. The analysis proved that performing the correct parameters would cause the pitcher to perform more efficiently. The first parameter is “leading with the hips.” The correct form would be for the pelvis to lead the trunk in the early cocking phase. The incorrect form is to stay vertical in this phase.

The second parameter is “hand-on-top position,” which would be described as having the forearm pronated in order to keep the hand on top of the ball rather than having the forearm supinated to have the hand under the ball. The third parameter is having the arm in throwing position. The correct form is to have the elbow at its maximum height during shoulder abduction before taking a stride. The fourth parameter is “closed-shoulder position.” The correct form is to have the shoulder pointing towards the target. The pitcher would look as if his back is facing towards home plate rather than his chest. The fifth parameter is having the “stride foot pointing towards home plate.”

An inverse dynamics technique was used to calculate the humeral internal rotation torques (HIRTs) and the elbow valgus loads (EVLs).

Their hypothesis was that if the 5 biomechanical pitching parameters were performed correctly, it will lower the humeral internal rotation torque and elbow valgus load while preserving pitch accuracy and velocity.

Biomechanical Performance of Baseball Pitchers with a History of UCL Reconstruction

Glenn S. Fleisig and his colleagues performed a study at the American Sports Medicine Institute in Birmingham, Alabama. Their investigation focused on differences in kinetics and kinematics with pitchers after UCL reconstruction and pitchers who have not had the surgery. Eight Major League Baseball organizations which included the Los Angeles Dodgers, Baltimore Orioles, Cincinnati Reds, Houston Astros, Kansas City Royals, New York Yankees, Philadelphia Phillies, and Tampa Bay Rays agreed to participate in the study during spring training in 2014. Seventy-seven active minor league baseball pitchers from the eight organizations were chosen to participate.

Thirty-nine pitchers had a history of UCLr, and thirty-eight were part of the control group. Each player in the UCLr group was matched with a player who did not have surgery and played at the same league level (A, AA, AAA). The study began with eighty pitchers, but three subjects were eliminated because further investigation revelaed that those three pitchers had arm surgery that was not related to UCLr. The pitchers with UCLr that were selected had to have surgery less than 4 years prior to the study in order to eliminate the effects of aging, other injuries, and changes in pitching. They also had to be active pitchers in spring training that were competing for a position in the regular season.

Four hypotheses were tested. The first hypothesis pertained to differences in elbow and shoulder biomechanics between the UCLr group and the control group. The second hypothesis was that the UCLr group would show characteristics of “holding back” or being hesitant, which included limited trunk forward tilt, shortened stride, and excessive shoulder horizontal adduction. The third hypothesis stated that the UCLr group would have a late arm cock compared to the control group. The fourth hypothesis stated that there would be differences in shoulder abduction and lateral trunk tilt between the two groups.

A 10-camera automated Raptor motion capture system was set up around a pitching mound in each organization’s spring training facility. The athlete was required to wear body-fit shorts, baseball socks, spikes, and a baseball cap. Twenty-three reflective markers, measuring 10 millimeters in diameter, were attached onto each pitcher all over their body. On the lower limbs, the markers were attached to the third metatarsal, lateral malleolus, lateral femoral epicondyle, greater trochanter, lateral superior tip of the acromion. On the upper limbs, the markers were attached on the medial humeral epicondyle, mid-forearm, radial styloid, and dorsal surface of the hand.

Four markers were also placed the baseball cap in the front, back, top, and sides of the head. The pitcher was allowed to throw as many warm-up pitches until he felt comfortable enough to throw pitches for the data collection. Then the pitcher was instructed to throw ten fastballs in the strike zone at maximum effort. The catcher sat behind home plate which was 18.4 meters from the mound, as it would be in a game setting. The markers placed on the pitcher were tracked at 240 Hz by the motion capture system while the speed of the ball was captured with a radar gun.

The results showed that there were no significant differences in kinetics and kinematics between the pitchers with UCLr and the pitchers who did not have surgery.

The Effect of UCL Reconstruction on Pitch Velocity in Major League Baseball Pitchers

Drew S. Lansdown and Brian T. Feeley conducted a study at the University of California, San Francisco, for The Orthopaedic Journal of Sports Medicine. Their study focused on changes in pitch types, fastball velocity, and statistics before and after UCLr. Their hypothesis was that there would be a decrease in velocity for fastballs after UCL reconstruction. At the beginning of their investigation, 129 major league baseball players were identified as athletes who had UCL reconstruction. The group was narrowed down to eighty MLB pitchers for the final analysis. Twenty-one pitchers were left-handed, and fifty-nine pitcher were right-handed.

Public data was used to do research on the active baseball players that were chosen to participate. Only pitchers who had to undergo primary UCL reconstruction were included in the study. Those who had multiple surgeries were not included. The baseball player also had to have at least two active years before and two active years after surgery in order for the investigators to compare the data. Each player’s individual statistics were noted as well. This included earned run average (ERA), wins, innings pitched (IP), strikeouts per game, walks per game, fielding-independent pitching (FIP), and wins above replacement level (WAR). Each pitcher’s pitch type and the velocity of each pitch from the 2002 to 2012 seasons were obtained and split into preinjury and postinjury data.

The results of the study reflect the changes in statistics for each baseball pitcher that had UCL reconstruction. The percentage of fastballs thrown decreased from 64.8% before injury to 60.4% after surgery. The average fastball velocity decreased from 91.3 mph to 90.6 mph. the eight pitchers that were younger than 25 years old showed no changes in fastball velocity after surgery (91.2 to 91.7 mph). The thirty-eight players that were between the ages 25 and 30 showed a decrease in fastball velocity (91.8 to 91.0 mph). The pitchers between the ages 30 and 35 had no significant difference in fastball velocity (90.4 to 90.3 mph). Lastly, the pitchers that are 35 years and older threw a slower fastball after surgery (91.7 to 88.8 mph). For the starting pitchers, the innings pitched decreased from 127.8 innings to 82.0 innings per year. For relief pitchers, the innings pitched decreased from 50.1 innings to 36.4 inning per year.

The pitch velocity for curve balls, sliders, and changeups did not change after surgery. The only difference that occurred within these pitches are an increase of percentage for sliders that were thrown.

This is the first study done about UCL reconstruction for baseball players that included statistics from before surgery and after rehabilitation. However, there are some limitations in this study. For example, Lansdown and Feeley obtained the pitchers’ statistics from public sites and the data may be inaccurate, which would make the results invalid. There may be errors in fastball velocities, pitch types, and other pitch velocities that were documented and obtained. Some UCLr cases may have not been documented on these public sources, so those that were undocumented could not be used for this analysis. On the other hand, a control group of pitchers that did not have UCL reconstruction were not included to compare the UCLr group. Wear-and-tear of other joints and ligaments can be the cause of decreased velocities and can be shown with pitchers who did not have the surgery.

References

Davis, J. T., Lumousvasti, O., Fluhme, D., Mohr, K. J. Yocum, L.A., ElAttrache, N. S., Jobe, F. W. (2009). The Effect of Pitching Biomechanics on the Upper Extremity in Youth and Adolescent Baseball Pitchers. The American Journal of Sports Medicine 37(8), 1484-91.
Fleisig, G. S., Leddon, C. E., Laughlin, W. A., Ciccotti, M. G., Mandelbaum, B. R., Aune, K. T., Escamilla, R. F., Macleod, T. D., & Andrews, J. R. (2015). Biomechanical Performance of Baseball Pitchers with a History of Ulnar Collateral Ligament Reconstruction. The American Journal of Sports Medicine 43(9), 1044-50.
Lansdown, D.A., Feeley, B. T. (2014). The Effect of Ulnar Collateral Ligament Reconstruction on Pitch Velocity in Major League Baseball Pitchers. The Orthopaedic Journal of Sports Medicine 2(2), 1-5.