I agree with what I have read, about the Frame Speed. Try using atleast 15! I animate in 24. Yeah, you have to make alot more frames, but it pays off!
This is a short run loop I made:
http://www.truploader.com/view/334234
This is actually a slow motion run loop, just up'ed to 72 FPS.
As you can see, more frames, and faster rate of frames. Gives a smoother overall look!
And also, even though I know this was a blood test. You should be more "carefull" when you draw, so you remove some of the "wobblieness" (Mark: Both feet when he lands).
If I'm going to be really picky. The transition where he face his opponent to show him his back, and do a backwards kick. Is too fast, just add a couple of frames in between :)