Lactic Acid

Definition: Lactic acid is a by-product of anaerobic glycolysis, a fancy name for the process which supplies your muscles the energy they need when you're working at an all-out pace. When you work out at a very high intensity, or anaerobically, lactic acid may build up in the blood faster than the body can remove it. Excessive lactic acid can actually slow contractions in skeletal muscles and is thought to cause muscle soreness if not flushed out of the body.