Lactic Acid Is Not Muscles' Foe, It's Fuel

[rhiandmoi]

Lactic Acid is Not Muscles' Foe, It's Fuel

Everyone who has even thought about exercising has heard the warnings about lactic acid. It builds up in your muscles. It is what makes your muscles burn. Its buildup is what makes your muscles tire and give out.

...

But that, it turns out, is all wrong. Lactic acid is actually a fuel, not a caustic waste product. Muscles make it deliberately, producing it from glucose, and they burn it to obtain energy. The reason trained 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.

[nomad55]

just goes to show you how little we are worth as a bunch of chemicals. it used to be around one dollar. just goes to show how dated i have become.

[DaGuyWitBluGlasses]

The reason trained 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.

So if your muscles are not readily and efficiently absorbing lactic acid then…

[Troodon]

It seems to me that the biochemistry in the article is all wrong. Your cells break down glucose to form pyruvate, and then they can use mitochondria to efficiently break down that pyruvate while forming ATP and other small energy-carrying molecules. In the absence of sufficient oxygen, they can also convert pyruvate to lactate (the conjugate base of lactic acid), forming some ATP. This process is far less efficient than the one performed by mitochondria, but it does not require oxygen.

Because muscles usually have a lot more sugar than they do oxygen, once they run out of oxygen they go ahead and power themselves by converting pyruvate to lactate, but once you are done exercising, the muscles have to use energy to convert the lactate back to pyruvate so that it can be fed to the mitochondria.

Thus, while the article makes some interesting claims about the causes of muscle soreness, I'm very suspicious about all of the details.

[rhiandmoi]

I think the point of the article is that what you thought was happening biochemically in the muscles is wrong.

[Troodon]

As far as I can tell, the scientist quoted in the article makes the claim that lactic acid buildup is not what causes the acidity that leads to muscle pain during exercise. That is a reasonable claim to make, although I haven't read his papers so I can't judge it.

The bad science is never in the direct quotes of the scientist, and so I suspect that it is due to the article author's poor understanding of the topic.

[Silas Sparkhammer]

I was taught that the pain comes from small tears and rifts in the muscle fibers, which regrow to make more and bulkier muscles after exercise. i.e., that it isn't chemical, but material. (Or that it isn't chemical only.)

Silas

[Troodon]

Originally Posted by Silas Sparkhammer

I was taught that the pain comes from small tears and rifts in the muscle fibers, which regrow to make more and bulkier muscles after exercise. i.e., that it isn't chemical, but material. (Or that it isn't chemical only.)

Silas

I've heard this about the soreness that occurs hours to days after exercise, but I think that the article is mostly talking about the pain you get while exercising that forces you to stop.

[Casey]

In cases of extreme lack of glucose, lactic acid can be used to make pyruvate by the liver, which can be run through the citric acid cycle (in reverse) to make glucose for the muscle. It's normally a waste product, but has a benefit.