Post by jsommerdpt on Oct 28, 2009 15:34:44 GMT -6
Dear Dr. Fleisig, I am a physical therapist and new to the world to motion capture and 3D technology. I would like to use my K-vest system to collect data on youth baseball players trunk rotation, and also on kinematic sequencing while hitting a ball off a tee. I understand my system is limited and better geared toward golf swing data collection, but are you aware of any normative data for trunk rotation during both throwing and batting? Any help is appreciated. Also, are you aware of any data or research that has investigated a potential link between risk of injury and limited trunk rotation. Thank you in advance, and I look forward to reading your reply.
Post by Glenn Fleisig, Ph.D. on Oct 29, 2009 10:40:01 GMT -6
I recommend that you read the following articles:
1. Putnam, CA. 1993. Sequential motions of body segments in striking and throwing skills: description and explanations. Journal of biomechanics. 26; 125-135.
2. Stodden D, Fleisig G, McLean S, Lyman S, Andrews JR. 2001. Relationship of pelvis and upper torso kinematics to pitched baseball velocity. Journal of Applied Biomechanics. 17; 164-172.
3. Ellenbecker TS, Ellenbecker GA, Roetert EP, Silva RT, Keuter G, Sperling F. 2007. Descriptive profile of hip rotation range of motion in elite tennis players and professional baseball pitchers. American Journal of Sports Medicine. 35; 1371-1376.
4. Vad V, Gebeh A, Altcheck D, Norris B. 2003. Hip and shoulder internal rotation range of motion deficits in professional tennis players. Journal of Science and Medicine in Sport. 6(1); 71-75.
5. Wright J, Richards J, Hall S. 2002. Influence of pelvic rotation styles on baseball pitching biomechanics. Sports Biomechanics.
6. L’Hermeitte M, Polle G, Tourny-Chollet C, Dujardin F. 2006. Hip passive range of motion and frequency of radiographic hip osteoarthritis in former elite handball players. British Journal of Sports Medicine. 40; 45-49.
7. Fleisig G, Barrentine S, Zheng N, Escamilla R, Andrews JR. 1999. Kinematic and kinetic comparison of baseball pitching among various levels of development. Journal of Biomechanics. 32; 1371-1375.
Let me throw out a few numbers for you to chew on...
From our latest database, at the instant of front foot contact with the mound the pelvis should be "open" between 22 and 43 degrees. The upper trunk should be slightly closed, with between 41 and 58 degrees of axial rotation between the pelvis and upper trunk. The shoulders should be about horizontal with each other (anywhere from 11 degrees "uphill" to 3 degrees "downhill").
Peak velocity of pelvis "opening" should be between 510 deg/s and 670 deg/s. That should be followed shortly after with peak velocity of the upper trunk opening (between 1070 deg/s and 1220 deg/s).
Keep in mind that these numbers come from particular optical motion capture systems. In theory, all optical systems and all electromagnetic systems (such as the K-vest) should find the same numbers. However the world is not perfect, so you need to be cautious in comparing measurements from your system with data collected in different ways.
Thank you for the response and the article references. I look forward to reading them. Additionally, I am a level 3 TPI medical professional, and have seen some of the data from TPI and the kinematic sequence is supposed to be present on the new K-vest software, but if you have any further suggestions I would be glad to hear them.