Lactic Acid

[scitsofreaky]

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

By GINA KOLATA

Published: May 16, 2006

 

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.

 

Coaches and personal trainers tell athletes and exercisers that they have to learn to work out at just below their "lactic threshold," that point of diminishing returns when lactic acid starts to accumulate. Some athletes even have blood tests to find their personal lactic thresholds.

 

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.

 

The notion that lactic acid was bad took hold more than a century ago, said George A. Brooks, a professor in the department of integrative biology at the University of California, Berkeley. It stuck because it seemed to make so much sense.

 

"It's one of the classic mistakes in the history of science," Dr. Brooks said.

 

Its origins lie in a study by a Nobel laureate, Otto Meyerhof, who in the early years of the 20th century cut a frog in half and put its bottom half in a jar. The frog's muscles had no circulation — no source of oxygen or energy.

 

Dr. Myerhoff gave the frog's leg electric shocks to make the muscles contract, but after a few twitches, the muscles stopped moving. Then, when Dr. Myerhoff examined the muscles, he discovered that they were bathed in lactic acid.

 

A theory was born. Lack of oxygen to muscles leads to lactic acid, leads to fatigue.

 

Athletes were told that they should spend most of their effort exercising aerobically, using glucose as a fuel. If they tried to spend too much time exercising harder, in the anaerobic zone, they were told, they would pay a price, that lactic acid would accumulate in the muscles, forcing them to stop.

 

Few scientists questioned this view, Dr. Brooks said. But, he said, he became interested in it in the 1960's, when he was running track at Queens College and his coach told him that his performance was limited by a buildup of lactic acid.

 

When he graduated and began working on a Ph.D. in exercise physiology, he decided to study the lactic acid hypothesis for his dissertation.

 

"I gave rats radioactive lactic acid, and I found that they burned it faster than anything else I could give them," Dr. Brooks said.

 

It looked as if lactic acid was there for a reason. It was a source of energy.

 

Dr. Brooks said he published the finding in the late 70's. Other researchers challenged him at meetings and in print.

 

"I had huge fights, I had terrible trouble getting my grants funded, I had my papers rejected," Dr. Brooks recalled. But he soldiered on, conducting more elaborate studies with rats and, years later, moving on to humans. Every time, with every study, his results were consistent with his radical idea.

 

Eventually, other researchers confirmed the work. And gradually, the thinking among exercise physiologists began to change.

 

"The evidence has continued to mount," said L. Bruce Gladden, a professor of health and human performance at Auburn University. "It became clear that it is not so simple as to say, Lactic acid is a bad thing and it causes fatigue."

 

As for the idea that lactic acid causes muscle soreness, Dr. Gladden said, that never made sense.

 

"Lactic acid will be gone from your muscles within an hour of exercise," he said. "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.

 

Mitochondria even have a special transporter protein to move the substance into them, Dr. Brooks found. Intense training makes a difference, he said, because it can make double the mitochondrial mass.

 

It is clear that the old lactic acid theory cannot explain what is happening to muscles, Dr. Brooks and others said.

 

Yet, Dr. Brooks said, even though coaches often believed in the myth of the lactic acid threshold, they ended up training athletes in the best way possible to increase their mitochondria. "Coaches have understood things the scientists didn't," he said.

 

Through trial and error, coaches learned that athletic performance improved when athletes worked on endurance, running longer and longer distances, for example.

 

That, it turns out, increased the mass of their muscle mitochondria, letting them burn more lactic acid and allowing the muscles to work harder and longer.

 

Just before a race, coaches often tell athletes to train very hard in brief spurts.

 

That extra stress increases the mitochondria mass even more, Dr. Brooks said, and is the reason for improved performance.

 

And the scientists?

 

They took much longer to figure it out.

 

"They said, 'You're anaerobic, you need more oxygen,' " Dr. Brooks said. "The scientists were stuck in 1920."\

 

http://www.nytimes.com/2006/05/16/health/n...serland&emc=rss

[Asimov]

I don't know of any of my Personal Training manuals or textbooks that said that muscle soreness after 2 to 3 days was caused by lactic acid build-up.

 

That delayed onset muscle soreness (DOMS) is caused by micro-tears in the muscle fibers. Not sure what it says about lactic acid though, I'll have to double check that.

 

Just a comment that Dr. Brooks is a little misinformed when it comes to "what scientists are saying" regarding lactic acid build-up.

 

The thing is, LA build-up occurs between 30 seconds and 1 minute bouts of exercise. So, stuff like the 100M sprint or a relay race and especially athletes who play in shifts like in hockey or basketball would be the ones who are most affected by that build-up. It's not that your muscle fatigues, causing you to stop, it's that the pain is so high (acid?! Hello!!!!) that you have to either slow down and let your aerobic system take over or stop altogether.

 

My PT manual, from what I remember, does say that it is ok to train in the anaerobic zone (past the anaerobic/lactic acid threshold), but to start those bouts at a minimum ratio of 1:3 (1 part anaerobic sprinting, 3 parts active rest) and then try to increase that ratio in order to increase your tolerance to lactic acid.

 

If you do go for too long in your anaerobic zone, you run the risk of injuring yourself, and you pretty much just stop because your muscles DO quit working. Dr. Brooks may have tested this stuff on rats, but he's probably never fucking worked a day in his life if he can't even grasp that basic concept.

[pandora]

I don't remember much being said about lactic acid being harmful or causing muscle soreness (I think those are from other metabolic processes), but I do remember from biochem that lactic acid is produced when an organism is operating under anaerobic conditions. The lactic acid is used in some reaction that will allow the body to use NAD+, ATP, glucose, and eventually oxygen again. I forget the details, but I don't think this contradicts what you've said, chef... in my schooling, lactic acid wasn't a bad guy, just an indicator of anaerobic conditions (like Asimov said).

[Dhampir]

.

[Fweethawt]

I was just getting ready to say, "I'll just wait to hear what Asimov says about this.".

 

I used to work out quite often, and I did it with several othe people who did the same. I've never seen anyone even attempt to work through the burn. Sure, we pushed it a little. But like Asimov stated, if you go to far, your muscles WILL stop working and there won't be a damn thing you can do about it.

[Asimov]

It also increases the risk of injury...although with athletes, they're usually one big walking injury risk.

[Fweethawt]

It also increases the risk of injury...although with athletes, they're usually one big walking injury risk.

I used to use an amino acid drink that kept the acid levels from building up as quick as they normally would.

 

I can't think of the name of it right now.

 

Is it L-Carnintine?

[Asimov]

It also increases the risk of injury...although with athletes, they're usually one big walking injury risk.

I used to use an amino acid drink that kept the acid levels from building up as quick as they normally would.

 

I can't think of the name of it right now.

 

Is it L-Carnintine?

 

Do you mean Glutamine? Or Creatine?

[Amanda]

 

Scitsofreaky, I remember this from back in my college days... maybe something about lactic acid did contribute negatively to the property, all or none, in muscle response.

 

Unfortunately, I'm probably revealing more about my age here. *sigh*

 

In another thread we're both participating, it seems people there think modern science never goes back on their findings. Here's another example, with this new finding about lactic acid. Sheesh, I just can't win.

 

Thanks for sharing this article!

[scitsofreaky]

I was just getting ready to say, "I'll just wait to hear what Asimov says about this.".

Why do you think I posted this here?

It's not that your muscle fatigues, causing you to stop, it's that the pain is so high (acid?! Hello!!!!) that you have to either slow down and let your aerobic system take over or stop altogether.

I have plenty of personal experience with this pain. It is one of the most uncomfortable feelings I have ever felt (and I have food poisoning right now). I played soccer for over 10 years, and it wasn't a problem during the game, but practices could get pretty bad. And track was bad too. I ran the 400m (the most brutal run ever), and lactic acid build up was definitly an issue at practice and meets.

Well, all that was pointless, oh well, I'm sick, leave me alone.

[Fweethawt]

It also increases the risk of injury...although with athletes, they're usually one big walking injury risk.

I used to use an amino acid drink that kept the acid levels from building up as quick as they normally would.

 

I can't think of the name of it right now.

 

Is it L-Carnintine?

 

Do you mean Glutamine? Or Creatine?

Okay, it might have been Creatine now that I think about it. It was something that came in a powdered form. When mixed with water, it produced an orange flavored (almost like a pop/soda) drink. I would drink about twelve to sixteen ounces about forty-five minutes to a half an hour prior to working out, and I would also drink another twelve to sixteen ounces during the workout.

 

Whatever it was, it kept the pain away and my progress grew by leaps'n bounds just within a month's time. No injuries here either.

[Asimov]

Okay, it might have been Creatine now that I think about it. It was something that came in a powdered form. When mixed with water, it produced an orange flavored (almost like a pop/soda) drink. I would drink about twelve to sixteen ounces about forty-five minutes to a half an hour prior to working out, and I would also drink another twelve to sixteen ounces during the workout.

 

Whatever it was, it kept the pain away and my progress grew by leaps'n bounds just within a month's time. No injuries here either.

 

That's good, there's a lot of research into creatine and it's properties.

 

Quick note...don't drink alcohol regularly while supplrementing creatine. It can adversely damage your system even more than it usually does.

 

So fwee, lay off the beers if you train!

[Fweethawt]

I don't train anymore.

 

I need to though.

 

The place that I work pays the membership fees for any of us that wants to join the gym across town. It's quite a laid-out gym, too.

 

I find it extremely hard to gather the ambition to get back into it after being on the graveyard shift for so long.

 

I know, it sounds like I'm whining, but it's true.

[Padreko]

Wow... This is a pretty interesting discovery as I was always told lactic acid was a waste product. Actually after just taking biochemistry this is a little unsettling.. LOL I got a hold of the actual paper written by the researchers and it was a tedious read .

 

But this is what is going on for all yall people who are not familiar with intracellular metabolism:

 

Metabolite oxidation is what keeps us going. We can take sugars, fatty acids, and amino acids and basically oxidize them down to carbon dioxide. The whole point of doing this is to get some electron carriers(NADH, NADPH, FADH) to shoot electrons through the electron transport system(ETS) causing the transporters of the ETS to pump protons to one side of the mitochondrial inner membrane. This produces and electrochemical gradient that powers an ATPase(with Hydrogen ions) which generate ATP from ADP and pi. ATP is like gas for your cells. OXYGEN is the final electron acceptor - you need it to complete the process which is represented in the reaction: .5O2 + 2electrons + 2Hydrogen ions --> H2O

 

Back to lactate:

 

Glycolysis is the pathway that transforms one molecule of glucose into two molecules of pyruvate. It was initially thought that when you are exercising your rate of metabolism(need for ATP) is far to great for the amount of oxygen that is in your muscle cells. This is actually only part of the story. You need NAD molecules to fuel glycolysis(currently going very very very fast in the CYTOSOL). The end product of glycolosis, pyruvate can either go into the mito's and be oxidized via the TCA cycle to CO2, and create some of those essential electron carriers (NADH, NADPH, and FADH) to fuel the ETS and create ATP. Only this cannot happen because it is thought that you don't have enough oxygen to be the final electron acceptor. The result is that Pyruvate is instead reduced to lactate to regenerate the NAD necessary to keep glycolosis going at a fast rate. Note, glycoslysis can net(generate) between 2 and 3 ATP's And we were all told that lactic acid is a by product.

 

New Discoveries:

 

Reading that publication was difficult, so I don't know if I got understood it completely, but from what I know, here is whats going on.

 

A. Glycolysis needs to go ultra fast so lactate is produced from pyruvate(the end produce of glycolosis) to regenerate NAD to keep the glycolysis going. Lactate is transported into the mitochondria and then reduced back to pyruvate which enters the TCA cycle via glutamate or something. Pyruvate -> TCA cycle -> Electron carriers -> ETS -> Biatch load of ATP

 

B. I'm not sure if the whole lack of oxygen thing is completely accurate based on this information.

 

I love science

[jjacksonRIAB]

It also increases the risk of injury...although with athletes, they're usually one big walking injury risk.

I used to use an amino acid drink that kept the acid levels from building up as quick as they normally would.

 

I can't think of the name of it right now.

 

Is it L-Carnintine?

 

Do you mean Glutamine? Or Creatine?

Okay, it might have been Creatine now that I think about it. It was something that came in a powdered form. When mixed with water, it produced an orange flavored (almost like a pop/soda) drink. I would drink about twelve to sixteen ounces about forty-five minutes to a half an hour prior to working out, and I would also drink another twelve to sixteen ounces during the workout.

 

Whatever it was, it kept the pain away and my progress grew by leaps'n bounds just within a month's time. No injuries here either.

 

I read somewhere that creatine prompts a synthesis of mitochondrial ATP, but I've also heard that creatine causes nothing but water retention in the powdered form, and was next to useless for weight training.

 

The reason I got concerned about lifting was because I kept getting hypertension in the wrists and along my forearms, causing me to not be able to lift without actual pain (not burning) and holding me back on my training. On top of that, it's next to impossible to evaluate microfractures in the bones, but premature wear on cartilage is a good indicator. A lot of weightlifters end up suffering through problems such as this and I dont' want to go through it.

 

I want to just try some classic exercises that don't stress non-regenerative tissues too much. Fortunately I'm a mesomorph, so it doesn't take much to get where I need to be -probably one of the few good traits that I can claim.

[Asimov]

I read somewhere that creatine prompts a synthesis of mitochondrial ATP, but I've also heard that creatine causes nothing but water retention in the powdered form, and was next to useless for weight training.

 

According to my PT book, creatine has been shown to be effective in weight training.

 

The reason I got concerned about lifting was because I kept getting hypertension in the wrists and along my forearms, causing me to not be able to lift without actual pain (not burning) and holding me back on my training. On top of that, it's next to impossible to evaluate microfractures in the bones, but premature wear on cartilage is a good indicator. A lot of weightlifters end up suffering through problems such as this and I dont' want to go through it.

 

Crosstraining and gradual progression might help that.