Short Update About Lactate, Lactic Acid and Fatigue

From a scientific/pedantic point of view, road cyclists have some common myths or misconceptions about lactic acid and lactate. However, from a practical point of view, these facts shouldn’t change your approach to training. Not at all. Anyways, here is a short update about lactate and why you shouldn’t care too much.

Lactic acid vs lactate

Lactic acid practically doesn’t exist in human bodies because the acid dissociation constant of lactic acid is 3.86. So at a pH value of 3.86, there is equilibrium between lactic acid (that’s the acid version of lactate) and lactate (‘the base version’). But in humans, we have a pH around 7.4 and only under extreme conditions, e.g., life-threatening disease or demanding exercise(!) reach pH values below 7.0. Furthermore, the pH scale is logarithmic, so there are always more than 1000 molecules of lactate for each lactic acid molecule in your body. Therefore, talking about lactate instead of lactic acid is a bit more correct.

Is lactate actually protecting you?

Lactate as a protector might sound somewhat counterintuitive from what you have heard in school or your local cycling club. As well as your practical experience when you suffer during training and races. The lesson has been: Lactate has been declared to be the devil itself, and you should train to avoid it (or learn to deal with it).

But what if lactate had a different role?

Who said that lactate causes your muscles to collapse?

Studies indicate that lactate has a protective function for your muscles. When you work very hard, your extra-cellular levels of potassium increase rapidly. Therefore, you can reach potassium levels that require intensive care in a hospital during heavy anaerobic work. Still, since your new friend lactate is there, you can deal with much higher potassium levels without heart arrhythmia. In addition, without lactate, time to exhaustion reduces rapidly in muscles working out in a fluid with elevated potassium concentration, proven in several studies with rats.

So maybe you shouldn’t blame lactate next time you suffer on the roads. Instead, it might have a protective role that keeps you going.

If you’re pragmatic, there are no reasons to be too concerned about the physiology behind the role of lactate. After all, no matter what position you believe lactate has, it’s (still) all about pedalling harder.