Paper Title
Pitching Analysis of Body Variables According to Ball Velocity in Amateur Baseball Pitchers using Gyro Sensor
Abstract
In baseball, pitching with maximum ball velocity is an important factor for a pitcher's success. Some studies have
used the inertial sensors in a manner to compensate for these limitations of the motion capture system for obtaining kinematic
data. For this reason, inertial sensors (gyro sensor) were also used in this study to analyze body variables during pitching
performance. Thus, the purpose of this study was to examine the correlation of ball velocity with body variables in eight
amateur baseball pitchers. In this study, they performed 10 to 15 maximal fastball pitch trials. Pitching velocity was measured
by speed gun. The wearable gyro sensor was used to investigate the body variables (horizontal abduction and abduction of
shoulder, trunk rotation angle (anterior and posterior), trunk rotation angular velocity, food direction, stride length) during the
pitching performance. The mean and standard deviation data from the eight amateur pitchers was used for data analysis. We
calculated a Pearson correlation coefficient to determine the associations between ball velocity and body variables. According
to result, ball velocity significantly correlated with the horizontal abduction and abduction of shoulder at arm cocking, torso
angular velocity and stride length (p<0.05). When the external rotation is greater, stronger shoulder contraction may occur due
to the action of stored elastic energy, the myotatic reflex, and a greater rate of force production during pre-stretched and
contracting muscles during arm acceleration phase. For stride length, it is regarded a not only critical kinematic factor for
determine the timing of kinetic chain events but also transitioning energy to the pitching arm from lower extremity. As
increased trunk rotation angular velocity, levels of trunks action develop more advanced and led to increases in energy transfer
to the pitching arm. Thus, these body variables should be considered to increase the ball velocity, which is an important ability
of the baseball pitcher in training and rehabilitation.
Keywords- Gyro, Baseball, Pitcher, Ball velocity, Kinematics, Biomechanics