The way animation tends to work is that to give it that real "OOMPH" on impact, there has to be some overshoot. One of the simplest examples is a bouncing ball. Upon hitting the ground, it squishes down. When it bounces up, it stretches. Although it doesn't really happen, it's for that snap of action. That's where a lot of those long legs and backwards elbows come from.
Ahh, I understand the way that happens now. :) They do prove to be some the funniest frames, too. As @fineillsignup says, animation wasn’t meant to be paused, hehehehe