Lactic Acid Guide
The Truth about Lactic Acid
Surprisingly the truth is that lactic acid actually protects against the acidosis it was accused of causing and as such is a helpful product that can actually allow muscles to contract for longer. When we look back at the literature it becomes evident that scientists have been questioning the misconception of lactic acid for decades (Wilkie 1979) so it is amazing how this myth still perpetuates.
To understand why lactic acid isn’t the enemy we must deconstruct the lactic acid myth. As explained the belief is that lactic acid is produced by the cell when there is not enough oxygen or the energy requirements are more than the cell can produce using the oxidative phosphorylation system. It is then thought that the acid environment caused by the lactic acid decreases the functionality of the muscle to contract.
“lactic acid does not make the cell acidic”
The fact is that lactic acid is not the source of acidosis in the cell. When we look at the full reaction of the conversion of glucose to pyruvate (glycolysis) and then lactic acid what we see is that there is no net production of hydrogen ions (acid). Even more interesting than this is the fact that if we feed glycogen and not glucose into the glycolysis reaction it actually results in consumption of a hydrogen ion and is thus reducing the acid within the cell!
Also as explained earlier, if we look at the conversion of pyruvate to lactate
Pyruvate + H+ + NADH → Lactate + NAD+
we see that the conversion of pyruvate to lactate not only consumes a hydrogen ion (acid) but also produces NAD+ which allows the whole glycolysis cycle to continue
Glucose + 2 NAD+ + 2 ADP + 2 Pi → 2 Pyruvate + 2 NADH + 2 H+ + 2 ATP + 2 H2O
So lactic acid is actually produced to buffer the cell against acidosis and helps to keep going the reactions that the cells need to produce energy in demanding times.
“lactate or lactic acid actually buffers the cell against acidosis”
Once the lactic acid has been produced is has a few fates and these have been discussed earlier. It is interesting to know at this point that the transporter that is responsible for removing lactic acid from the cells is also a symport (meaning that it carries two things out of the cell together) for hydrogen ions, meaning that as lactic acid leaves the cell it can take acid with it which further protects the cell from acidosis.