The Lactic Acid Myth

Let’s blow your mind right now: no matter how hard you ride, there’s no Lactic Acid in your muscles.

Don’t worry, not everything you know about “lactic acid” is wrong, just most of it. When you’re working hard it’s actually “Lactate” that your body is producing rather than “lactic acid,” but that’s mostly semantics (I’ll refer to it here properly as lactate), the real myth that needs to be debunked are the ill-effects that most people attribute to lactate.

We’re told that when we’re riding hard and our muscles start to burn it’s because our legs are filling with lactate and that its build up is why we hit our limit and have to back off the effort. Unfortunately as nice as that explanation is, it’s, you guessed it, myth. The ugly truth is that we still don’t know exactly why our legs fatigue when we ride hard, it could be micro tears in the muscle fibers, it could be acidosis (caused by other processes), it could be muscle cell depolarization, it could be something else, but we do know that it’s not from the lactate.

Our bodies are producing lactate all the time, but we produce much more of it as part of anaerobic energy production, such as during that 2min climb you hammer up on every group ride. Luckily lactate is actually a fantastic fuel source for our bodies! Not only is it one of the main energy sources for our heart muscles, but our livers also take up the lactate and convert it back to glucose in a process known as the Cori Cycle. Recent research has even shown that much or most of the lactate produced during exercise stays within the muscles’ cells and is used by our mitochondria to produce even more energy for the working muscles. Possibly more exciting is that recent research has suggested lactate may be a powerful signaling agent for your cells to increase production of mitochondria (these are the energy factories of the cell) leading to even better aerobic efficiency.

So in sum: there’s no lactic acid causing your legs to hurt, what we have in our bodies is Lactate, and it’s certainly not the devil molecule it was once made out to be, in fact, it’s actually a crucial part of keeping our muscles moving when they are fatigued. So next time your triathlete friend mentions how much their legs are hurting from all the “lactic acid” on a climb, just roll your eyes and pedal ahead!