Lactic acid builds up in muscles during intense exercise and causes a burning sensation. However, it is not responsible for next-day muscle soreness.

Usually nothing to worry about, lactic acid is produced as a result of anaerobic metabolism – the process during which the body produces energy without oxygen. Here’s more information about lactic ...

Lactic acid has long been vilified, but new research shows that it doesn't impair muscle function. In fact, it might actually be good for you. Like all great villains, lactic acid has been ...

ABC News' own Dan Childs takes on an exercise challenge. — -- Some experts call it "hitting the wall," others call it "the bonk": Either way, it's the all-around unpleasant situation when an ...