From a scientific/pedantic point of view, there are some common myths or misconceptions about lactic acid and lactate among road cyclists. However, from a practical point of view, these facts shouldn’t change your approach to training. Not at all. Anyways, here is 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 pH around 7.4 and only under extreme conditions e.g. life-threatining disease or very hard exercise(!) reach pH values below 7.0. The pH scale is logarithmic, so there is always more than 1000 molecules of lactate for each lactic acid molecule in your body. Therefore it is a bit more correct to talk about lactate instead of lactic acid.
Is lactate actually protecting you?
This might sound rather counterintuitive from what you have heard in school or in 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). You’ve been told that when lactate accumulates in your muscles and when there is too much of it, you have to reduce intensity because your legs suffer.
But what if lactate had a different role? Who said that lactate causes your muscles to collapse?
There are studies indicating that lactate has a protective function for your muscles. When you work very hard, your extra-cellular levels of potassium increases rapidly. During heavy anaerobic work you can reach potassium levels that would require intensive care on a hospital, but since your new friend lactate is there, you can deal with much higher levels of potassium without heart arrhythmia. Without lactate time to exhaustion reduces rapidly in muscles working out in a fluid with high potassium concentration. This has been proven in several studies with rats.
So maybe you shouldn’t blame lactate next time you suffer in the roads. It might actually have a protective role that keeps you going.
If you’re pragmatic, there are no reasons to be too concerned about the physiology behind role of lactate. After all, no matter what role you believe lactate has, it’s (still) all about pedaling harder.