Kinematic and kinetic findings in high vs. low consistency professional baseball pitchers

Abstract

While the performance metric ball velocity has often been associated with increased kinetics at the upper extremity and risk of injury in baseball pitchers, it is unclear if the performance metric pitch location consistency has any positive/negative associations with pitching kinetics. Professional pitchers subdivided into high(Hcon) and low(Lcon) consistency groups were instructed to throw 8–12 fastballs while assessed with motion-capture technology(480 Hz). To further assess pitching consistency, 95% confidence ellipses with comparisons of major and minor radii were conducted with an external comparison to a cohort of high school pitchers. Lastly, kinematic and kinetic values were compared between Hcon and Lcon professional pitchers. Professional baseball pitchers(n = 338) had consistency in pitch location comparable to high school pitchers(n = 59) (22.0 ± 6.7 vs. 23.2 ± 7.5% grid width respectively, p-value = 0.21). Hcon professional pitchers(n = 91) compared to Lcon pitchers(n = 98) had a smaller major radius(15.2 ± 3.0 vs. 26.3 ± 5.9 respectively, p-value<0.001) and a smaller minor radius(9.4 ± 1.9 vs. 16.1 ± 4.4 respectively, p-value<0.001) in the 95% confidence ellipses. Hcon pitchers compared to Lcon pitchers had increased arm slot(59.7 ± 13.5 vs. 54.7 ± 12.4° respectfully, p-value = 0.009), trunk tilt(-33.4 ± 9.1 vs. −37.2 ± 8.9° respectfully, p-value = 0.004), and trunk lateral flexion(-27.1 ± 9.3 vs. −31.8 ± 9.0° respectfully, p-value<0.001) at ball release. These pitchers also had lower shoulder(112.4 ± 15.9 vs. 118.3 ± 15.1% BW respectfully, p-value = 0.001) and elbow distraction forces(110.5 ± 17 vs. 117.0 ± 15.2% BW respectfully, p-value = 0.006) during arm deceleration. Professional pitchers who approach a sidearm style of pitching, typically involving less contralateral trunk tilt, may achieve higher consistency in their throws while also experiencing diminished peak distractive forces at the elbow and shoulder.