Originally Posted by Polaris OBark

That is technically correct, but what we are both saying (independently of one another, I promise!) is that it isn't a physiologically relevant biochemical distinction.

Let's take a slightly different example: Acetic acid (the main ingredient of vinegar).

If you put acetic acid into water, the molecule rapidly dissociates into two ions: a hydrogen ion, aka a proton, and an acetate ion. The dissociation is partial, so an equilibrium will exist between these two ions (the proton ion and the acetate ion) and the un-dissociated form, which we call the acetic acid molecule.

Because it is in an equilibrium, if some physiological or chemical process removes some of the acetic acid, then the equilibrium will almost instantaneously replenish it until nearly all of the acetate ion has been depleted. In other words, you won't have one without the other present, so whether the acetate ion is getting consumed, or the un-ionized acetic acid is getting consumed, isn't really relevant.

This isn't unique to acetic acid, but it is true of any "weak" organic acid, like pyruvic acid, lactic acid, ascorbic acid, etc.

What I think all of us agree upon is that the lactate/lactic acid doesn't hang around very long. Its transitory appearance is associated with anerobic respiration (fermentation) and as soon as enough oxygen is present, all of it is consumed, so it normally wouldn't accumulate in muscle tissue, especially hours after exercise.

Originally Posted by vespasianus

What I don't get is why the heck this would cause someone to be frustrated.

And Polaris is right.