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If you "feel the burn," you need to bulk up your mitochondria
By Robert Sanders, Media Relations

http://www.berkeley.edu/news/media/releases/2006/04/19_lactate.shtml

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.

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Ben Stansall/European Pressphoto Agency
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."

pre svega, postoji terminoloski problem:
anaerobni izvori energije - STARI termin koji se zasniva na ideju da misic u odredjenim situacijama postaje anaeroban (tj, u njemu nema kiseonika) - netacno. U celiji UVEK ima kiseonika. Novi naziv i mnogo precizniji je 'oxygen independent glycolysis' ili kiseonikom nezavisna glikoliza. Mrzi me da ulazim u fiziologiju/biohemiju pa predlazem da se procita:

Gladden, L.B. Lactate metabolism: new paradigm for the third millenium. J Physiol 558.1 2004. pp5-30

Robergs, R.A., Ghiasvand, F., Parker, D. Biochemistry of exercise-induced metabolic acidosis. Am J Physiol Regul Integr Comp Physiol 287: R502-R516, 2004.

Gandevia, S. C. Spinal and Supraspinal Factors in Human Muscle Fatigue. Physiol Rev 81: 1725–1789, 2001.

Westerblad, H. Et al. Muscle Fatigue: Lactic Acid or Inorganic Phosphate the Major Cause? News Physiol. Sci. • Volume 17 • February 2002

A jedna od boljih  fiziologija je od Brooksa i Fahey-a... nisam stigao da je procitam, eno je u ormanu

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Ja bih stvari klasifikovao PREMA CILJU a ne prema fizoloskim 'reakcijama'. Na ovaj nacin bih izbegao da ne vidim shumu od drveca.
Cilj 'aerobnog trcanja' nije da bih ja popravio 'aerobiju' vec da bih bio BRZI na odredjenoj deonici, ili da bih se brze oporavljao od kratkih sprinteva, ili da bih razvio kardiovaskularni sistem (rekreativci/prevencija). U zavisnosti od CILJA, KARAKTERISTIKA SPORTISTE i KONTEKSTA izbor sredstava, metoda i opterećenja sa ciljem dostizanja ovih ciljeva bio bi izabran.

koju bi klasifikaciju onda stavili?

Oduvek sam govorio da je svaki sportista individua za sebe i da ga kao takvog moramo i tretirati, a ne sporvoditi treninge koji mu ne odgovaraju, ali nije bitno, jer je "neko bitan" tako rekao da treba!

Mladene, slažem se da je ta A,A-A,A podela isuviše stara, ali rekreativcima to objašnjava sve... 

Zavisi... o kome pricamo... zavisi koji metod koristimo kao 'aerobni' trening. BTW, ja nikako ne koristim tu 'aerobno/anaerobnu' klasifikaciju koja je stara i bazirana na pogresnim modelima misicnog zamora

nema ih nabijas zglobove i kolena .. ali svakako po meni ima vise + nego - posledica

A loshe strane 'aerobnog vezbanja'
Sta je to 'aerobno' vezbanje?

upravno sam se vratila sa kardio treninga - da, osećam se motivisano

Kad bi svi šefovi ovog sveta shvatili da smo mnogo bolji radnici kad se lepo izvežbamo

Kratak osvrt na to koje su koristi aerobnog vezbanja:

Dugotrajni fizioloski efekti:

- ubrzanje metabolizma (vece sagorevanje kalorija)
- prevencija kardiovaskularnih bolesti snizenjem krvnog pritiska i usporavanjem aterosklerotskog procesa
- poboljsava sposobnost srca da pumpa krv
- poboljsava unos kiseonika i aerobnu kondiciju
- poboljsava misicnu izdrzljivost
- poboljsava fleksibilnost i pokretljivost
- pojacava misicnu snagu
- poboljsava fizicke mogucnosti u svim uzrastima i sportskim usmerenjima
- jaca zdravlje i usporava starenje

Psiholoski efekti:

- redukuje stres
- poboljsava dnevne sposobnosti
- bolje osecanje zbog kontrole telesne tezine i boljeg izgleda
- moze biti vrlo zabavno i motivisuce