The Science of Lance

From National Geographic:

"When people reach exhaustion, their muscles build up acid, which causes the muscles to stop contracting. But Armstrong's muscles produce about half as much acid as the average person's muscles do when they get fatigued. This allows him to recover much faster than other people.

'You can see when Armstrong races, he can attack better than anybody,' Coyle said. 'He makes a break, then backs off and then breaks again, wearing [the others] down until they can't recover, and then he just takes off.'"