The DIY Biomechanics Lab: Initial Results


#1

As most people here know, I’m building a DIY biomechanics lab in my training facility located in Seattle, WA. We finished our control object a few weeks ago and filmed the first few test subjects just last week. I’m happy to report that my biomechanics intern and I have digitized the first two pitchers in our lab, and I’d like to share with you some preliminary kinematic data from one of them.

(Sorry if the image is a bit large.)

This still from our kinematic software shows a pitcher (video redacted for privacy) and his 3d model as digitized in our software. To smooth data collection, we used Butterworth filters of varying cutoff frequencies depending on residual analysis; this may not be the best way to do this, as a standard cutoff frequency tends to be more prevalent in research literature.

The graph shows the resultant velocities for the pitching arm hip/shoulder/wrist. (The vertical black line marker is the approximate time of shoulder maximum external rotation - or MER. The motion digitized represents foot strike to ball release.) You can see the velocity curves move in tandem with each other as expected with the modern concept of the kinetic chain - force is transferred from proximal to distal, and from the largest to smallest body part. In this case, the hip rotates quickly first, then the shoulders, and then the wrist.

This is only the preliminary data and results from the software. We plan on measuring far more variables with a report that is similar to what you might see from ASMI. (See also: Biomechanical Analysis of Dr. Mike Marshall’s Pitching Technique
http://www.baseballprospectus.com/news/images/Fleisig.pdf

  • PDF file)

Hope it was as exciting for you as it was for me! Three years in the making and we’re finally getting some real work done. Now, all we need are four more high-speed cameras and a lot better lighting… :wink:


#2

COOL :clapping:

I want one too


#3

[quote=“Slewbacca”]COOL :clapping:

I want one too[/quote]

Come on up to Seattle. :slight_smile:


#4

My son has already been asking me to.


#5

this is awesome. like slewbaccas son i might ask my dad to drive me up to seattle. lol. i live in southern california


#6

My son showed me this but KC is a long way for jumping in the car.


#7

How about make it portable and you go on the road!!!


#8

Oh, I get it. All of you guys are just pulling my leg.

(I don’t see a picture - just a red “X”.)


#9

Portability is the idea at some point, yes. We have a lot of plans.

Roger, I rehosted it below. See if that works.


#10

Thanks, Kyle.

Me thinks your pitcher represented by that graph has problems if wrist velocity is less than hip and shoulder velocity (assuming my thinking is correct about what is meant by wrist velocity).


#11

I’ve been staring at the chart for a couple of days now trying to understand what it means and failing miserably.

I believe the lines represent the velocity derived by the various factors (hip, arm, wrist). Is total velocity represented by the sum of the lines?

What does the graph look like for a pitcher with near perfect mechanics/efficiency? What should be we looking for?


#12

The NPA has been generating these kinds of graphs for a number of years now. There isn’t really a total velocity being represented but rather a sequence of velocities. What you should be noticing is the sequencing and progression of peak rotational velocities of the major parts of the kinetic chain. For sequencing, you should notice that the peak shoulder rotational velocity occurs after peak hip rotational velocity and peak arm rotational velocity occurs after peak shoulder rotational velocity. For the progression of peak rotational velocities, the peak rotational velocity of shoulder rotation should be greater than the peak rotational velocity of hip rotation and the peak rotational velocity of the arm should be greater than the peak rotational velocity of the shoulders.

In Kyle’s graph, the pitcher’s arm is slower than the shoulders indicating some issue (assuming I’m interpreting what the “Pitching Arm Wrist…” line represents).


#13

[quote=“bigal”]I believe the lines represent the velocity derived by the various factors (hip, arm, wrist). Is total velocity represented by the sum of the lines?

What does the graph look like for a pitcher with near perfect mechanics/efficiency? What should be we looking for?[/quote]

Total velocity is not measured by the sum of the lines - it’s segmental velocity, as Roger pointed out. And if we knew what perfect mechanics were with regard to these graphs, it would be a lot simpler :wink:

Roger,

Pitching Arm Wrist resultant velocity is being measured incorrectly, as is Shoulder Internal Rotation resultant velocity (we are getting readings of 500-600 deg/sec for 80 mph fastballs - like this pitcher - when it should be in the 5000-6000’s range). We’ve emailed Dr. Fleisig and Dave Fortenbaugh from ASMI to see if they can shed some light on the situation.