Effects of Weight Shift and Timing of Heel Lift during Stride on Ground Reaction Force, Ball Speed, and Stride Kinematics in Amateur Baseball Pitchers




Stephens, Brian

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Ball speed is one of the key predictors of success in baseball pitchers. While various factors have been demonstrated to contribute to ball speed, no study has examined how the movement of the center of pressure (COP) and timing of heel lift during stride affects the pitching biomechanics, and there is no consensus among the expert coaches as to how the pitchers should push off the pitching rubber. The purpose of the study was to investigate the effects of anterior-posterior weight shift and timing of heel lift during the stride phase on ground reaction force (GRF), ball speed, and stride kinematics in high school and collegiate baseball pitchers. Fifty-two pitchers performed fifteen pitches from an indoor pitching mound. A three-dimensional motion capture system, a high-speed camera, two force plates embedded in the mound, and a radar gun were used to collect the kinematic and kinetic data. Pearson correlation coefficients were used to study the relationship between variables. Observation of our data revealed that the COP location during the stride was not correlated with GRF, ball speed, or stride kinematics. However, the earlier timing of heel lift was correlated with more anteriorly located COP at peak anterior force and a more open pelvis at stride foot contact. The relationship between the timing of heel lift, COP location at peak anterior force, and timing of pelvis orientation suggests that instructions focusing on COP location during the stride may be an effective strategy to modify the timing of pelvis rotation in amateur pitchers.


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Ball speed, Center of pressure, Stride kinematics, Pelvis orientation timing, baseball, ground reaction force



Health and Kinesiology