Silver Star Mountain
Cross Country Ski Camps

News and Views

Posted by Norm Crerar May 25/06

LACTIC ACID-It’s good for you!!
Gina Kolata of the New York Times News Service

Who knew??

Anyone who has even thought about exercise has heard about lactic acid. It is what makes your muscles burn and its buildup makes your muscles tire and give out. Coaches tell athletes they have to learn to work out below their “lactic threshold” and some athletes use blood tests to determine the threshold.

Turns out this is all wrong. Lactic acid is actually a fuel, not a caustic waste product. Muscles make it deliberately, producing it from glucose and burn it for energy. The reason some athletes can perform so hard and so long is because their intense training causes their muscles to adapt so they more readily and efficiently absorb lactic acid.

George A. Brooks, Prof of integrative biology, U of C Berkley says the notion that lactic acid was bad took hold more than a century ago. “It was one of the classic mistakes in the history of science”. A theory was born when Nobel Laureate Otto Myerhoffin the early years of the 20th century cut a frog in half and put the bottom half in a jar. The frog’s muscles had no circulation, no source of O2. Myerhoff gave the muscles elec shock and after a few twitches the muscles stopped and were found to be bathed in lactic acid. The theory-lack of O2 to muscles leads to lactic acid which leads to fatigue.

Brooks, in research for a PhD in exercise physiology gave rats radioactive lactic acid and found they burned it faster then anything else he could give them. Published findings in the 70s brought him great grief from other researchers and had his papers rejected and research grants canceled. Eventually other researchers confirmed the work. “It became clear that it is not so simple to say that lactic acid is a bad thing and it causes fatigue”, said L. Bruce Gladden, Prof of health and human performance at Auburn Univ. “Lactic acid will be gone from your muscles within an hour of exercise but you get sore one to three days later. The time frame is not consistent and the mechanisms have not been found”.

The understanding now is that muscle cells convert glucose or glycogen to lactic acid. The lactic acid is taken up and used as a fuel by mitochondria, the energy factories in muscle cells. Brooks goes on to say that coaches believed in the lactic acid threshold theory they continued to do the right thing by working on endurance which increased the muscle mass mitochondria allowing the muscles to work harder and longer. Interval training before a race is good also as the extra stress increases the mitochondria mass even more.

Submit story ideas to info@xccamps.ca