Lactic Acid Guide
Lactic Acid – Misconceptions and Myths
If you ask most people what limits them from exercising at high intensities they will often reply saying “the burn” in the muscles being used and if you ask them what causes this burn they reply “lactic acid”. For near a century now it has been thought and widely taught that lactic acid produced by the muscles through anaerobic metabolism is responsible for this burn and resultant muscle fatigue, but in reality this simply isn’t true and there has actually never been any scientific evidence to suggest this is the case!
“even though we now clearly know otherwise”
As with many scientific discoveries, especially in years past, initial findings were later modified or disproven and it can take decades of changing beliefs before thoughts become more concrete, and this can definitely be said for lactic acid. The interesting thing in this case however is that even though we now clearly know otherwise, the myth is still widely believed to be reality and still referred to as gospel in the scientific community!
So where did it start?
To understand where the myth originated, we must go back to the origins and the initial works on the subject by Otto Meyerhoff and Archibald V. Hill who were both actually awarded the Nobel Prize for their work on carbohydrate metabolism in skeletal muscle.
Their work was carried out at a time when scientific thinking was that in order for muscle contraction to occur, oxygen was necessary to produce the energy required. The first important discovery they made was that in the absence of oxygen, glycolysis could occur and that lactic acid was a product of this reaction. Through further calculations they then determined that this reaction yielded large amounts of energy in a short time and could fuel rapid and powerful muscle contractions.
“in the absence of oxygen large amounts of energy could be produced”
What they also realized was that during intense muscle contractions the energy required by the muscles was up to 8 times more than could possibly be provided by oxygen alone at maximum consumption rates (Hill 1924).
This led them to the conclusion that large amounts of energy could be provided in the absence of oxygen by the conversion of glucose to lactic acid via glycolysis. Up to this point they were certainly correct in their thoughts but they then did something that is very dangerous in science and came to a conclusion based on logical thought. They concluded by simple ‘cause and effect’ that anaerobic (without oxygen) metabolism led to the production of lactic acid which was responsible for the acidosis in the cell and the resultant muscle fatigue.
“the thought that lactate production leads to acidosis is simply not true and should be removed from all future teaching”
Since this assumption was made there has been no hard evidence to support the case apart from simple correlations, which carry very little if any weight at all unless elaborated on by further investigations. The belief that the lactic acid produced releases a proton (H+) resulting in an acidosis is simply not true and must be removed from future teaching.