A comparison of standing and kneeling overhand throwing
Date
2011
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Overhand throwing is stressful to the shoulder and elbow joints, so it is no surprise that approximately 60% of shoulder injuries occur in baseball (8). Previous studies have attempted to link overhand throwing mechanics with injuries, however none have accounted for the contribution of the scapula despite its obvious role in shoulder movement. This is primarily due to the inabilities of traditional motion capture methods to track scapular motion. To overcome these inadequacies we intend to use ultrasound probes, alongside traditional motion capture to measure scapular movement. However, the vast amount of trunk translation associated with the standing overhand throw exceeds the mechanical limits of most ultrasound sensors. Therefore, the purpose of this study is to determine if kneeling throwing is similar to standing throwing, so that kneeling throwing can be used to accommodate for the mechanical limits of ultrasound in order to track scapular motion. Twenty-six college males were analyzed, and each subject threw from both a standing and kneeling position. Five of the seven primary kinematic variables were not statistically different between conditions, and for the two variables that were different, the time at which maximum external rotation occurred and shoulder rotation at ball release, there means remained within one standard deviation of each other. Ball velocity and linear shoulder excursion, or a measure of trunk tilt, were both, as expected, statistically different between conditions. Finally, a comparison of throw initiation methods showed the time at which stride foot contact occurred was not significantly different than the time at which the trunk reversed its rotation direction about the global z-axis. In conclusion, the kneeling throw appears to be representative of the standing throw, and it is assumed that if the humerus is moving in a similar than so is the scapula. Kneeling throwing may allow the use of ultrasound sensors to track scapular movement in further research.