Joint and segment sequencing and its relationship to ball velocity and throwing arm kinetics in professional pitchers

Self Cite

Background: It has previously been speculated that baseball pitchers who display excessive forearm pronation at foot contact (FC) have a higher propensity toward ulnar collateral ligament injury and subsequent surgery. Purpose: To evaluate the association between degree of forearm pronation/supination at FC and throwing arm kinetics in high school and professional pitchers, at both the individual (intrapitcher) and the group (interpitcher) level. Study Design: Descriptive laboratory study. Methods: High school (n = 41) and professional (n = 196) pitchers threw 8 to 12 fastballs while being assessed with a 3-dimensional motion-capture system (480 Hz). Pitchers at each playing level were divided into a supination or pronation subgroup depending on degree of forearm pronation at FC. Regression models were built to observe the relationship between forearm pronation at FC and kinetic and kinematic parameters of interest. Results: At both the individual and the group level of high school and professional pitchers, there was no significant correlation between forearm pronation at FC and elbow varus torque ( P min = .21). For every 10° increase in forearm pronation at FC in the individual high school pitcher, elbow flexion at FC decreased by 5°, whereas maximum elbow extension velocity was achieved 0.6% later in the pitch. In addition, elbow medial force increased by 4.1 N and elbow varus torque increased by 0.8 N·m for every 10° increase in forearm supination at FC. For every 10° increase in forearm supination in the individual professional pitcher, ball velocity increased by 0.5 m/s, shoulder external rotation at FC decreased by 11°, and elbow medial force decreased by 5.5 N. Conclusion: Supination- or pronation-predominant forearm motion during the pitch did not significantly differ between playing levels. Excessive forearm pronation at FC was not a significant risk factor for increased throwing arm kinetics for high school or professional pitchers. There was a weak positive association between forearm supination at FC and elbow varus torque in the individual high school pitcher. Ultimately, coaches and pitchers may be better served by redirecting their focus to other mechanical aspects of the pitch that may have stronger associations with injury risk implications as well as performance.

Section: Discussionmentioning

confidence: 72%

Forearm Pronation at Foot Contact: A Biomechanical Motion-Capture Analysis in High School and Professional Pitchers

Manzi

Dowling²,

Wang

et al. 2023

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“…While increased rotational velocities are essential to developing optimal ball velocity, proper sequencing of the velocities needs to be maintained to allow for the future evaluation of the timing of peak velocities and its influence on energy transfer during the pitch. 21 The increased energy transfer to the throwing arm may be beneficial in increasing ball velocity; however, we speculated it is possible that the increase in energy could also increase joint loading and torque across the elbow, potentially leading to injury and time lost from play. Within an individual pitcher, increased ball velocity has been shown to sustain increased elbow varus torque.…”

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Influence of Pelvic Rotation on Lower Extremity Kinematics, Elbow Varus Torque, and Ball Velocity in Professional Baseball Pitchers

Dowling

Knapik

Luera

et al. 2022

Background: Early pelvic rotation has been associated with decreased throwing arm kinetics in college baseball pitchers, though professional pitchers have yet to be examined. Purpose: To investigate the effect of pelvic rotation on trunk, pelvis and lower extremity kinematics, as well as throwing arm kinetics and pitch velocity in professional baseball pitchers. Study Design: Descriptive laboratory study. Methods: Data were analyzed for 157 professional baseball pitchers throwing fastballs using 3-dimensional motion capture (480 Hz). Pitchers were divided into an open pelvis (rotated toward target; n = 78) and a closed pelvis (n = 79) group based on pelvic rotation at foot contact. Variables of interest were compared between the groups using t tests and 2-way analysis of variance, while Spearman correlation was used to measure relationships between the variables of interest. Results: Pitchers in the open group had a longer stride length (81% ± 5% vs 77% ± 5% body height; P < .01, d = 0.74), greater lead knee flexion (49° ± 6° vs 47° ± 10°; P = .043, d = 0.33), faster peak knee extension velocity (424°/s ± 158°/s vs 325°/s ± 142 °/s; P < .01, d = 0.66), and faster ball velocity (39.1 ± 1.7 m/s vs 38.4 ± 2.1 m/s; P = .029, d = 0.35) compared with those in the closed group. There was no significant difference in elbow varus torque between the 2 groups (open: 87.8 ± 14.7 N·m, closed: 90.5 ± 17.2 N·m; P = .311). There were moderate negative relationships between pelvic rotation at foot contact and stride length ( r S = -0.385, P < .001), lead knee extension ( r S = -0.429, P < .001), and peak lead knee extension velocity ( r S = -0.359, P < .001). Conclusion: Professional pitchers who landed with an open pelvis demonstrated longer stride length, greater lead knee extension, faster lead knee velocity, and faster ball velocity compared with pitchers with a closed pelvis at foot contact. This increase in segment velocities and ball velocity was not associated with an increase in elbow varus torque and displays a potentially efficient method in which pitchers can increase ball velocity without an increase in elbow varus torque. Clinical Relevance: Instructing pitchers to rotate their pelvis toward the target at foot contact may allow pitchers to transfer momentum up the kinetic chain more efficiently, while producing greater ball velocity and limiting the torque sustained at the elbow.

“…9,18,19,37 Additionally, the timing of the kinetic chain is crucial, and temporal variations have significant impacts on both torque and ball velocity. 1,2,23,27,29,30 Professional pitchers with properly sequenced kinetic chains were reported to have faster ball velocity with no difference in elbow varus torque compared with pitchers with discordant kinetic chain sequencing. 23 In the present study, we did not investigate lower extremity, pelvis, and trunk kinematics or the timing of the transfer of energy to the throwing arm, which may be why we found no significant relationships when comparing across different pitchers' arm path and elbow varus torque.…”

Section: Discussionmentioning

confidence: 99%

Relationship Between Arm Path, Ball Velocity, and Elbow Varus Torque in Professional Baseball Pitchers

Dowling,

Hodakowski,

Olmanson

et al. 2023

Self Cite

Background: Currently, most pitching instructors suggest a shorter arm path—the total distance the arm travels during pitching. Theoretically, this combination allows for better body segment sequencing, a more efficient energy transfer through the kinetic chain, and increased ball velocity, while limiting elbow varus torque. Hypothesis: Shorter arm paths would be associated with increased ball velocity and decreased elbow varus torque. Study Design: Descriptive laboratory study. Methods: A total of 182 professional pitchers threw 8 to 12 fastball pitches while evaluated by 3-dimensional motion capture (480 Hz). The arm path was calculated as the total distance the hand marker traveled during the pitch. The pitch was divided into early, late, and total arm paths. A linear regression model assessed the interpitcher relationship between arm path, elbow varus torque, and ball velocity. A linear mixed-effects model with random intercepts assessed intrapitcher relationships. Results: Interpitcher comparison showed that total arm path weakly correlated with greater elbow varus torque ( P = .025). Strong correlations were found between ball velocity and early ( R2 = 0.788; P < .001), late ( R2 = 0.787; P = .024), and total arm paths ( R2 = 0.792; P < .001). Strong positive intrapitcher correlations were found between elbow varus torque and early ( R2 = 0.962; P < .001) and total arm path ( R2 = 0.964; P < .001). For individual pitchers, there was a large variation in the early (30.1 ± 15.7 cm) and late (21.4 ± 12.1 cm) arm path. For every 30-cm (11.8-inch) increase in early arm path (the mean range for an individual pitcher), there was a 1.29-N (β = 0.0429) increase in elbow varus torque and a 0.354 m/s (0.79 mph) (β = 0.0118) increase in ball velocity. Conclusion: A shorter arm path correlated with decreased elbow varus torque and decreased ball velocity in intrapitcher comparisons. Determining the individual mechanics that decrease elbow varus torque may help coaches and trainers correct these patterns. Clinical Significance: A shorter arm path during the pitch can decrease elbow varus torque, which limits the load on the medial elbow but also has a detrimental effect on ball velocity. An improved understanding of the impact of shortening arm paths on stresses on the throwing arm may help minimize injury risk.