Knee Angle and Stride Length in Association with Ball Speed in Youth Baseball Pitchers

Abstract

The purpose of this study was to determine whether stride length and knee angle of the leading leg at foot contact, at the instant of maximal external rotation of the shoulder, and at ball release are associated with ball speed in elite youth baseball pitchers. In this study, fifty-two elite youth baseball pitchers (mean age 15.2 SD (standard deviation) 1.7 years) pitched ten fastballs. Data were collected with three high-speed video cameras at a frequency of 240 Hz. Stride length and knee angle of the leading leg were calculated at foot contact, maximal external rotation, and ball release. The associations between these kinematic variables and ball speed were separately determined using generalized estimating equations. Stride length as percentage of body height and knee angle at foot contact were not significantly associated with ball speed. However, knee angles at maximal external rotation and ball release were significantly associated with ball speed. Ball speed increased by 0.45 m/s (1 mph) with an increase in knee extension of 18 degrees at maximal external rotation and 19.5 degrees at ball release. In conclusion, more knee extension of the leading leg at maximal external rotation and ball release is associated with higher ball speeds in elite youth baseball pitchers.

Individual factors associated with baseball pitching performance: scoping review

“…They also found less maximal lead knee flexion (LKF) and greater lead knee extension angular velocities in high-velocity groups. van Trigt et al 18 also found that a more extended knee was positively correlated with ball velocity. Based on low,14 moderate15 16 20 23 25 and high18 risk of bias studies, a lower LKF and a greater FTT may be associated with greater ball velocity.…”

“…van Trigt et al 18 also found that a more extended knee was positively correlated with ball velocity. Based on low,14 moderate15 16 20 23 25 and high18 risk of bias studies, a lower LKF and a greater FTT may be associated with greater ball velocity. Because of the conflicting and heterogenous nature of the results, we cannot conclude that other ball release parameters are associated with ball velocity.…”

“…Stodden et al 15 found a significant correlation between SHA and ball velocity but not with shoulder abduction, whereas Oyama et al 16 investigated the differences in kinematics among pitchers with or without excessive contralateral trunk tilt and found that pitchers with excessive contralateral trunk tilt showed less upper torso flexion at foot contact and had higher ball velocity . Among five studies reporting on lower limb kinematics,14 15 17–19 Werner et al were the only one reporting an association between a greater knee flexion or elbow flexion and increased ball velocity. In all five studies that investigated stride length,14 17 18 20 21 Sgroi et al were the only one to find that stride length was associated with ball velocity.…”

“…Among five studies reporting on lower limb kinematics,14 15 17–19 Werner et al were the only one reporting an association between a greater knee flexion or elbow flexion and increased ball velocity. In all five studies that investigated stride length,14 17 18 20 21 Sgroi et al were the only one to find that stride length was associated with ball velocity. Solomito et al 22 showed that a more tilted trunk in forward flexion at ball release is associated with greater ball velocity.…”

“…Stodden et al 23 also observed a positive association between upper torso rotation angle and ball velocity, as well as pelvis orientation and ball velocity. van Trigt et al 18 observed that increased knee flexion of the lead leg at SER was negatively associated with ball velocity. Finally, Solomito et al 24 found that higher contralateral trunk lean also caused greater ball velocity.…”