I recently read an article
(http://www.sportsci.org/jour/0102/rar.htm), which has changed my opinion regarding the lactic acid related "burn" people experience while exercising.
I trust you guys will check out the article, but I'll post a few paraphrased bits, nonetheless.
If you follow how many protons are produced/consumed during lactate fermentation you'll see that the common belief just doesn't hold.
A proton is produced when glucose is phosphorylated with the aid of hexokinase. One more proton is produced when fructose-6-phosphate is phosphorylated with the aid of PFK. Two more protons are produced when 2 G3Ps are oxidized with 2 NAD+s.
So, four protons are produced.
The production of 2 pyruvates consumes two protons. And the production of 2 lactates consumes two protons (the 2 lactates use up another 2 protons but they're from 2 NADHs and therefore would be used in chemiosmosis, so I didn't include them).
So, four protons are consumed, no net gain or loss.
What about the proton from the carboxyl group?
Well, the first carboxyl group containing intermediate produced in the glycolytic pathway is 1,3-biphosphoglycerate. The dephosphorylation of 1,3-bisphosoglycerate results in 3-phosphoglycerate, but the removal of the phosphate from the first carbon makes it the carboxylate form, not the carboxylic acid form, so it's already ionized. And I believe that each "acid" produced en route to lactate is in the ionized form.
Moreover, I read elsewhere (http://www.bio.mtu.edu/campbell/401l16bp1.html) that the carboxylate ion of pyruvate interacts with lactate dehydrogenase (the enzyme which converts pyruvate to lactate and vice versa), so lactate has to be produced, not lactic acid.
The protons, which cause the exercise related acidosis come from incomplete glycolysis (no lactate produced) and ATP hydrolysis.
So, lactate actually delays acidosis by reducing the proton load.
To be honest, I'm surprised I haven?t come across many dissenters on this topic.
I'd be interested to hear what you guys think.