From Mind the Science Gap, summer edition:
Lactic Acid, it’s likely that most of us have heard of it—whether it was from a 1980′s Richard Simmons aerobics tape or from your personal trainer last week. The fitness industry has tossed this term around for years to describe the infamous “burn” during a workout. We were told that during intense exercise, lactic acid builds up in our muscles causing us to experience fatigue. Just this morning, I took a cycling class and the instructor’s exact words were, “you should be feeling that lactic acid build up, just 1 more minute on this hill (to push harder). If you’re not feeling the burn, add more resistance on your bike!” Most of us will just nod our heads and suffer through the workout, but research has presented an entirely different story behind lactic acid. As a fitness professional who has heard it all, I feel as though I need to set the story straight.
The confusion around lactic acid started in the 1920’s when scientists observed higher levels of lactic acid in a frog’s blood and muscle tissue when oxygen was completely absent (which, unless you are dead, doesn’t happen in the human body). This eventually led to the idea that lactate is only produced during really intense exercise (i.e when you’re breathing heavily and working as hard as you can). Given that lactate levels and exercise intensity were highly correlated, it’s no wonder that this assumption of cause and effect caught on so fast. Here’s the catch that probed one particular scientist to dig a little deeper into the dynamic of lactic acid build up and fatigue: lactic acid forms during the presence of oxygen too—in fact,absence of oxygen is not really the basis of lactic acid formation at all.
Read the complete post–and comment–here.