Well actually Battue, current thought is lactic acid has little to do with muscle soreness. It is the leakage of calcium from the muscle's "trigger", IE the sarcoplasmic reticulum. Calcium is the primary intracellular ion that allows muscles to contract. It has to be pumped via active transport back into the cells to allow the next contraction to occur. That is why most of us can't do this:

http://www.youtube.com/watch?v=mqnF7j9coes

There is no substitute for repeatedly picking up heavy stuff at a high heart rate.