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

Abstract

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.

Kinematic Parameters Predictive of Pitch Velocity in Youth to Professional Baseball Pitchers: A Qualitative Systematic Review

“…This suggests that a longer stride length improves the efficiency of energy transfer through the kinetic chain by allowing increased time for the pelvis to reach an open position at foot contact. Pitchers landing with an open pelvis also have greater lead knee extension, 10,41 which has been noted in professional pitchers. 20 Solomito et al 36 reinforced the focus on knee extension and pitch velocity by noting that greater knee flexion was associated with a decrease in ball velocity.…”

“…Of the 12 studies included in this review, there were 9 descriptive laboratory studies: Alderink et al, 4 Aguinaldo and Escamilla, 1 Dowling et al, 10 Keller et al, 16 Murata, 24 Oyama et al, 27 Smith et al, 35 Solomito et al, 36 and Tanaka et al 40 ; and 3 single-episode cross-sectional studies: Cross et al, 7 Orishimo et al, 26 and Sgroi et al 34 There were 930 pitchers in total, with 429 (46.1%) youth, 164 (17.6%) high school, 153 (16.5%) collegiate, and 184 (19.8%) professional athletes. The mean age was 17.2 years (range, 12.1-25.5 years).…”

“…Dowling et al 10 retrospectively reviewed the pitching evaluations of 157 professional pitchers with a focus on pelvic rotation at foot contact. Pelvic rotation was defined as a line from the anterior superior iliac spine in relation to the coordinates of the pitching evaluation.…”

“…Of the 12 studies included in this review, there were 9 descriptive laboratory studies: Alderink et al, 4 Aguinaldo and Escamilla, 1 Dowling et al, 10 Keller et al, 16 Murata, 24 Oyama et al, 27 Smith et al, 35 Solomito et al, 36 and Tanaka et al 40 ; and 3 single-episode cross-sectional studies: Cross || et al, 7 Orishimo et al, 26 and Sgroi et al 34 1. Studies categorized by anatomic location and kinematic contributors to ball velocity are described, with specific measurement descriptions for kinematic parameters of interest provided in Table 2.…”

“…(continued) Question Alderink (2021) 4 Aguinaldo (2019) 1 Cross (2023) 7 Dowling (2022) 10 Keller (2016) 16 Murata (2001) 24 Orishimo (2023) 26 Oyama (2013) 27 Sgroi (2015) 34 Smith (2019) 35 Solomito (2022) 36 Tanaka (2022) 40 6. Was the selection process likely to select subjects/ participants that were representative of the target/reference population under investigation?…”