Is Lactate the Best Surrogate for Physiological Testing?

Lactate is the best surrogate to look at what's the mitochondrial function of an athlete. If you have a very good mitochondrial function, you can clear lactate very well. So that means that you don't accumulate much lactate in the muscles and they use it for fuel. When you're like 3.5 watts per kilogram and you have four millimoles of lactate, you're far away to be at an elite level. That doesn't mean that that person is doomed. It's just like a good reference to know, like, oh, wow, we need a lot of work with this kid.