The Lactic-Acid Myth
9/28/06

If you've ever complained of lactic acid burning in your quads during hill repeats, you're not alone. BUT, we're not even close when we blame lactic acid as the source of the burn. Research in the past showed that lactate levels increased along with intensity & muscle fatigue. Therefore it was thought that lactate was shutting the muscles down.

New studies have recently shown that lactate in the body is not actually an acid and is not causing soreness, burning, and/or fatigue. Shocking news... I know, it took me a while to process this new concept. What is causing "the burn" and muscle failure? We know for sure from our own experience that as our intensity increases past what we either feel or know as our anaerobic threshold, there's an increasing rate of fatigue and intramuscular burning that will soon cause muscular failure if the intensity is not decreased. True, so what's causing this?

When you exercise at a moderate level, glycogen in the muscle is the primary source of fuel for quick energy. If the demands for glycogen are too great due to an increasing intensity, glucose from the liver jumps in and helps out. This is where we get into "the burn". Glucose creates a much more acidic environment than glycogen when burned for fuel, releasing two units of hydrogen as compared to one from glycogen. This flooding of hydrogen lowers the blood's pH creating acidosis and eventually causing the burn you feel on those hard efforts.

Lactic acid is not a bad thing. It actually keeps the body going through hard workouts and intense intervals. It gets converted back into a fuel source and shuttles the accumulating hydrogen out of the muscle cells and helps to buffer the burn.

So, next time you hear someone cussing lactic acid, chuckle inside and embrace the lactate.

Happy training,
Joe