Influence of Three Drills on Pelvic Motion in Baseball Swing – a Pilot Study

Abstract

Background: The intersegmental coordination between the pelvis and hand is a key component of sound hitting mechanics in baseball. Several training methods have been used in the field to alter the hand-pelvis coordination during hitting, but the effectiveness of these methods has not been experimentally examined. Objectives: The purpose of this study was to investigate the immediate effects of three selected hitting drills on the kinematics of the hand and pelvis during baseball hitting. Methods: Nine Division I Collegiate baseball players were recruited and underwent four hitting drills in a random order: (1) No drill (BASELINE), (2) holding an 8.5-inch ball with the elbow of the front arm (FRONT), (3) holding the same ball between the bicep and forearm of the back arm (BACK), and (4) stepping down with their left leg from a 4-inch step (STEP). The hand and pelvis motion were recorded with a camera-based motion capture system with markers placed on each subject. Linear distance between the hand and pelvis, magnitude of pelvic rotation, and acceleration of pelvic rotation at bat-ball contact were calculated. Results: The STEP drill was associated with an increase in the hand-pelvis linear distance at ball contact (P = 0.02). The FRONT and BACK drills were associated with an increase in the magnitude of pelvic rotation (P = 0.05, P < 0.01). The STEP drill was also associated with a decrease in the pelvic acceleration (P < 0.01). Conclusions: All three drills (Front Ball Drill, Back Ball Drill, and Step-Down Drill) contributed to significant differences in affecting the participant’s hand-pelvis linear distance at ball contact, magnitude of pelvic rotation at ball contact, or pelvic acceleration at ball contact. The three hitting drills tested could be used to address different deficiency in hitting mechanics, specifically targeting hand-pelvis linear distance at ball contact, magnitude of pelvic rotation at ball contact, and pelvic acceleration at ball contact.