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EP-01 Fitness Assessment, Exercise Training, and Performance of Athletes and Healthy People

Influence Of Back Foot Orientation On Kinetics And Kinematics During Baseball Pitching


Bonaker, Rebecca MS; Aguinaldo, Arnel PhD, ATC

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Medicine & Science in Sports & Exercise: August 2021 - Volume 53 - Issue 8S - p 49
doi: 10.1249/01.mss.0000759652.98479.a2
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The objective of pitching is to generate the most speed, accuracy, and efficiency as possibly in every pitch. The pitching motion is a kinetic chain, where the lower extremity and trunk generate force during the wind up and stride phase which is transferred to the ball through the shoulder and elbow.

PURPOSE: The purpose of this study was to assess the back foot orientation’s influence on ball velocity and injury risk. A secondary purpose was to see if the back foot orientation has a relationship to different aspects of the kinetic chain.

METHODS: The data examined was from seventeen collegiate baseball pitchers (age = 20.4 ± 1.2 years, height = 1.87 ± 0.05 m, mass = 94 ± 7 kg). One representative fastball pitch was extracted in this study in which 3D motion data was collected utilizing a 38 reflective marker set and a 12-camera motion analysis system at a sampling rate of 400 Hz. Back foot orientation data was extracted at maximum knee height of the stride leg during the stride phase. Statistical analyses were conducted in SPSS 25.0 using bivariate pearson correlation coefficients analysis.

RESULTS: Back foot orientation data was collected at knee high of the stride leg (98.8 ± 6.2). There were no significant interactions between backfoot orientation and ball velocity or injury risk. Back foot orientation with respect to ball velocity resulted in a p-value of 0.160, indicating that there was no relationship between these variables in the data collected. Back foot orientation with respect to MEVT (injury risk) and MSIRT (maximal shoulder internal rotation torque) resulted in p-values of .718 and .896, respectively, which also indicated that there was not a significant relationship between these variables in the data collected. There was a significant association (r2 = 0.25, p = 0.041) between backfoot orientation and RPVZ_WORK_RFA (induced work of the forearm by pelvic rotation).

CONCLUSIONS: The research conducted in this study was the first to look at foot orientation during pitching. The information gained is a starting point to see how backfoot orientation influences the kinetic chain. Although there were no statistically significant interactions between back foot orientation and ball velocity, MEVT, and MSIRT, there was a significant interaction with the mechanical energy transferred to the right forearm from pelvic rotation.

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