Lactic acid not the cause of muscle fatigue?



Squint

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Jul 27, 2003
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fleshbroiler said:
Am curious if anyone else saw this article. Lactic acid buildup doesn't cause muscle fatigue anymore? When did this happen?

A few million years ago. However, it's probably been known by man for quite sometime, perhaps decades.
 

Piotr

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Squint said:
A few million years ago. However, it's probably been known by man for quite sometime, perhaps decades.
And now women know it too. :D
 

daveryanwyoming

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Oct 3, 2006
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fleshbroiler said:
Am curious if anyone else saw this article. Lactic acid buildup doesn't cause muscle fatigue anymore? When did this happen?
Yep, lactic acid(really blood lactate) isn't the bad guy. It's not really news but people are so entrenched in the lactic acid soreness myth they don't want to hear it. Try googling "lactic acid soreness" and see how many hits you get debunking that firmly held belief.
 

sogood

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Aug 24, 2006
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Looks like anti-doping agencies will have another class of drug to put on their list. :rolleyes:
 

sogood

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So what causes the pain?

Ischaemia? Tissue oedema and stretch of pain fibres? Local pH alteration and pain fibre stimulation? Others?
 

sogood

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beerco said:
What difference does it make? It's not like there's anything you can do about it.
Once upon a time there was nothing one could do about those chest pains of heart attacks, and people just died. Then science changed everything. :p
 

beerco

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sogood said:
Once upon a time there was nothing one could do about those chest pains of heart attacks, and people just died. Then science changed everything. :p

My bad, I didn't realize you were personally a scientist working on some of that "science" stuff to eliminate muscle pain :rolleyes:
 

no1kung1

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Mar 29, 2007
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Yeah, I saw that article in the times earlier this week. My issue is that it doesn't really say anything of revelant importance. It tells us that muscle damage is caused by calcium leaks with the muscular tissue, but it doesn't reveal any sort of information that would change the way people train.

What am i supposed to start bringing Tums along on rides to aid recovery?
wink.gif
 

sogood

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Not sure about muscle damage, but my reading of it was that those leaky Ca channels was partly the explanation for muscle fatigue. Muscle fatigue could be reduced by reducing the "leakiness" of those ion channels, by 10-20%.
 

sugaken

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no1kung1 said:
but it doesn't reveal any sort of information that would change the way people train.
I've read about lactic acid not being the cause of muscular fatigue a few years back, but that didn't change my training a bit. If I understand it correctly, we're not even supposed to change how we train based on that knowledge.

Ken
 

TheDarkLord

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sogood said:
Not sure about muscle damage, but my reading of it was that those leaky Ca channels was partly the explanation for muscle fatigue. Muscle fatigue could be reduced by reducing the "leakiness" of those ion channels, by 10-20%.
Yes, but there probably is a reason why the body sends you pain signals when it does. If you tamper with it for the sake of 10-20% improvement, there is no saying what side-effects will happen - is it worth the risk of causing quasi-permanent damage somewhere in your body?
 

sogood

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TheDarkLord said:
Yes, but there probably is a reason why the body sends you pain signals when it does. If you tamper with it for the sake of 10-20% improvement, there is no saying what side-effects will happen - is it worth the risk of causing quasi-permanent damage somewhere in your body?
That depends on what was the source of stimulation of those pain fibres. You see, that argument only partly make sense as we all know that we train to push beyond our lactic/pain threshold in order to perform better. If we always use pain as the limit of our training and activities, then we are not likely to get stronger and better.
 

doctorSpoc

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Nov 18, 2005
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sogood said:
That depends on what was the source of stimulation of those pain fibres. You see, that argument only partly make sense as we all know that we train to push beyond our lactic/pain threshold in order to perform better. If we always use pain as the limit of our training and activities, then we are not likely to get stronger and better.
yes, but the ratcheting up of pain is very effective at limiting how much you can go beyond and for how long from the onset of pain... you are still limited, you can still only go so far beyond when the pain starts.. and what if nature factors in a bit of a buffer incase the organism is hard headed? so you are safe... so nature brings the real pain at 200 but damage doesn't really start 'til 225... but take the drug and you start feeling pain at 220 and can dig deep and get to 240.. denaturing the protiens in your leg muscles, causing permanent nerve damage.... who knows? nature doesn't usually just put limits on things like this just for kicks.... usually there is a really good reason. i mean think about it... a faster organism with greater endurance would likely be a more successful organism, so nature would limit this for nothing.
 

doctorSpoc

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one point... it seems like this is a possible mechanism for the muscles actually getting weak... not necessarilly the mechanism for a feed back loop that causes you to be in pain... that could be a related but completely separate mechanism... e.g. this could be just one many hundreds of signals that causes your brain to sense pain and slow you down.
 

Urkiola2

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Oct 4, 2007
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Lactic acid (2-hidroxipropanoic acid) is dissociated at a physiological pH to an anion of lactate (C3 H3 O3-) and a proton of Hidrogen (H+). That is, lactic acid is produced in the cytosol and then when in contact with interstitial fluid and of course with blood is dissotiated and converted to lactate. There are several theories about fatigued caused by lactate. However nowadays is been for a few years widely accepted that lactate per se does not cuase muscle fatigue neither acidosis, but the (H+) associated to lactate are the ones who cause acidosis. This can be caused from Lactate production and probably by an excess of ATP hydrolysis as well.

That is about "acidosis". Lactate is an indicator and probably an indirect contributor for that. A differnet thing is musce fatigue. There are many theories about it and still none of them has been fully proven. However Dr. Marks' research opens as Dr. Brooks says an "exciting and provocative"claim.
The study is based in the calcium channels leak in the heart muscle. It is thought that (H+) interferes with exitation-contraction coupling by competing with Ca++ for the binding sites of troponin C an therefore with muscle contraction. However the finding by Dr. Marks was that blocking those calcium channels leakage through a drug would diminish the degree of fatigue, though maybe there is something else different than Ca++ and insetad of (H+) competing with Ca++, maybe both are competing with something else...

Anyways. This finding still has to be proven with humans and with skeletal muscles instead of cardiac muscles.

To me, one thing is for sure. Lactate is a sure indicator that something is not going well within the muscles, whatever you want to name it fatigue or acidosis...but the real thing is that those whose blood lactate leves are lower will be performing better than those whose lactate levels are higher and their time to exhaustion (for whatever the cause could still be investigated) will be earlier.

Cheers.
 

Urkiola2

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doctorSpoc said:
yes, but the ratcheting up of pain is very effective at limiting how much you can go beyond and for how long from the onset of pain... you are still limited, you can still only go so far beyond when the pain starts.. and what if nature factors in a bit of a buffer incase the organism is hard headed? so you are safe... so nature brings the real pain at 200 but damage doesn't really start 'til 225... but take the drug and you start feeling pain at 220 and can dig deep and get to 240.. denaturing the protiens in your leg muscles, causing permanent nerve damage.... who knows? nature doesn't usually just put limits on things like this just for kicks.... usually there is a really good reason. i mean think about it... a faster organism with greater endurance would likely be a more successful organism, so nature would limit this for nothing.
Very good point.
 

TheDarkLord

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Dec 24, 2007
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Urkiola2 said:
To me, one thing is for sure. Lactate is a sure indicator that something is not going well within the muscles, whatever you want to name it fatigue or acidosis...but the real thing is that those whose blood lactate leves are lower will be performing better than those whose lactate levels are higher and their time to exhaustion (for whatever the cause could still be investigated) will be earlier.

Cheers.
So, if I am understanding you correctly, when we feel muscle fatigue, there is lactic acid build-up, but that is not what causes the fatigue. Is that right, or am I misunderstanding you?