Go to the track and start running around it as fast as you can. Then you will have a personal experience with lactic acid.
I'm not that up to speed on it and can't give a scientific explanation, but here's what I do know of it in regards to running.
When the lactic acid builds up in your body, you will slow down.
MaxVo2 is not as important as your lactate threshold level.
You can increase your running speeds by raising your lactate threshold, which does not require running at an all out pace.
You can actually get a pretty specific idea of what your threshold level is with some blood testers (like for diabetics).