3D Motion Analysis: 4D Motion
At Complete Game Physical Therapy we are dedicated to not only providing excellent care to athletes and active individuals following injury or surgery but also to helping reduce the likelihood injury occurring in the first place. We are currently working to help identify and address injury risk factors associated with adolescent baseball pitchers. We have been working with a local youth baseball program, Lowell Jr. Spinners Baseball, to gather data through our 3D motion analysis system, 4D Motion. In this short blog series I will first review background on what we were looking at with these pitchers and why, then review the data we collected, and finally show how we use the information to help athletes.
The American Orthopedic Society of Sports Medicine estimates that 45% of baseball players ages 13-14 will have arm pain during any given baseball season (stopsportsinjuries.org). There also has been reported as high as a sixfold increase in the number of Tommy John Surgeries (UCL reconstruction of the elbow) in high school players in the last decade (Melugin et al, 2018). These numbers definitely are consistent with what we see in the clinic. More and more youth baseball players, especially pitchers, are coming in for physical therapy following injury.
Overuse has been found to be the most common cause of pitching injury (Fleising et al 2006). But despite the widespread adoption of pitch counts in youth baseball (and thankfully starting this year in Massachusetts high school baseball, finally!) injury rates are not decreasing (Arnold et al, 2019). There is clearly more that can be done and pitching mechanics is another area that can be addressed to help reduce the likelihood of pitching injury.
The kinematic sequence is simply the idea that efficient pitching mechanics involve proper sequencing of the body segments proximal to distal or from the ground up. For a more in depth review of the kinematic sequence check out my blog on the subject. Recent research on kinematic sequence patterns in baseball pitching showed overall variability in the sequencing of the body (Lepinski et al, 2019). Basically even professionals don’t repeat a perfect sequence every time. There was consistency in the pattern of pelvis and torso timing with the pelvis reaching peak angular velocity first 96% of the time and torso reaching peak angular velocity second 91% of the time in healthy throwers. This data combined with the fact that intuitively it makes sense that power comes from the ground up makes this a good place to start researching with our pitchers.
To record the pelvis and torso mechanics we used the 4D motion sensor system. This is an inertial measurement unit (IMU) based sensor system where athletes wear small sensors in this case strapped to their chest and pelvis for biomechanic analysis. IMU based sensors have been used to quantify human movement and undergone a lot of technological improvements to become increasingly more accurate (Boddy et al, 2018). Recent research has shown that IMU’s are very accurate at capturing inter-segment timing sequence in the overhead baseball pitch (Li et al 2015). This made this system ideal for our purposes.
Check out our next blog to see how we were able to record the data and what the data showed about adolescent pitching mechanics. As always please feel free to reach out to me at gcrossman@completegamept.com or give us a call at 978-710-7204.