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Old 05-16-2006, 08:51 PM   #1
DrunkMonkey
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New York Times article

Lactic acid apparently acts as a fuel used by the mitochondria in muscles rather than making them sore due to a lack of oxygen.

"Faith is the great cop-out, the great excuse to evade the need to think and evaluate evidence. Faith is belief in spite of, even perhaps because of, the lack of evidence." -Richard Dawkins
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Old 05-17-2006, 03:07 AM   #2
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So, what does this mean? I can't care to read the article, to hungry right now.
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Old 05-17-2006, 08:02 AM   #3
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Hmmm....that sounds a little whack. He says muscles don't get sore until a few days later. I think when people say their muscles are getting sore they're referring to the fact that their muscles are sore at the moment they are tiring. Like when you've done so many squats and you can barely get the bar back up, it hurts.

It's not news that lactic acid doesn't cause the pain. Lactic acid is simply a byproduct of fermentation. How would mitochondria use the lactic acid as fuel? It doesn't make sense that cells would convert glucose to lactic acid. That would be adding an extra step. Glucose is the substrate of glycolysis, so that would mean that the cells would have to convert from glucose to lactic acid and then back again. Isn't pretty well understood that lactic acid fermentation in human cells is pretty much the same as the lactic acid fermentation in various forms of bacteria?
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Old 05-17-2006, 08:40 AM   #4
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Yeah, I'm a bit skeptical at least of the phrasing in that article. I seem to remember from Biology 101 that fermentation regenerates the reactants for glycolysis when oxygen isn't available so that at least the cell can continue to get a couple molecules of ATP from anaerobic respiration.
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Old 05-19-2006, 04:54 PM   #5
Martha Castro M.D.
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Quote:
DrunkMonkey wrote
New York Times article

Lactic acid apparently acts as a fuel used by the mitochondria in muscles rather than making them sore due to a lack of oxygen.
Humm?....

Lactic Acid is produced from pyruvate via fermentation.
+ +
Pyruvate+NADH+ H +=lactate+NAD

Lactic Acid is produced also by a bacteria called Lactobacillus.

Lactate is also part of a medical solution known as Ringer's Lactate solution, and we use it everyday in hospitals for fluid resuscitation after surgery or trauma where loss of blood has occurred.
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Old 05-19-2006, 05:10 PM   #6
baconeatingatheistjew
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My brother is a horse trainer. I called him when I read the article. He says that lactic acids are a bad thing (something to do with horses tying up). Any ways, here is an article I dug up, but I don't have a clue what it means:

Tying-Up
(set fast, azoturia, Monday morning disease, exertional rhabdomyolysis)
Dr J H Stewart BVSc BSc PhD MRCVS

Muscle disorders are a frequent cause of poor performance in horses and 'tying up' is the most common syndrome. Some horses are more susceptible than others. There appears to be a genetic component and a hormonal influence as the condition is more common in fillies. It is also more common in horses that are highly strung.

It is often mistakenly assumed that any horse with muscle pain or cramping after exercise has 'tied-up', and because of this there is a lot of confusion and controversy around the causes, diagnosis, and management of affected horses. Although a number of different muscle conditions produce the same signs, there are basically two types of true 'tying-up':


1. ACUTE STIFFNESS DURING OR AFTER EXERCISE The most common cause is hard exercise that exceeds the horses fitness level. Horses with respiratory viruses and subclinical infections are at increased risk.

2. REPEATED 'TYING-UP' Horses that suffer recurring stiffness after mild exercise, often have a history of poor performance and subclinical cases (reduced performance - but no stiffness or unevenness of gait) can occur.

Horses that 'tie up' repeatedly are referred to as 'chronic'. Chronic tying up is sometimes referred to as Recurrent Exertional Rhabdomyolysis (RER), or Polysaccharide Storage Myopathy (PSSM). One of the misconceptions with tying up has been that it is caused by high muscle lactic acid concentrations. If this was the case all horses would tie up after a race. Polysaccharide storage myopathy is a condition in which there is an accumulation of glycogen (a form of glucose) in muscle tissue. The glycogen that accumulates is abnormal in structure and prevents the horse from using the normal glycogen that is stored in muscle for use during exercise. Affected horses have the classical elevated muscle enzymes on a blood test and to diagnose PSSM requires muscle biopsies.

Polysaccharide Storage Myopathy (PSSM) Recurrent Exertional Rhabdomyolysis (RER)
Researchers have also found that when horses with this form of tying up have episodes of pain, the affected muscles have high levels of calcium trapped inside the muscle cells. Calcium, along with energy (ATP), is required for muscle contraction. To relax, the muscle must remove the calcium from inside its cells. In horses with RER, the process of calcium removal does not operate efficiently. This leads to an accumulation of calcium within the cell which prevents the normal relaxation of the muscle fibres. The muscles remain in a state of partial contraction leading to soreness and muscle damage.

This idea offers an explanation as to why some horses tie up shortly after they begin slow or medium work (ie aerobic exercise). When such horses are excited or under stress, they release increased amounts of the hormones that mobilise energy and stimulate muscular activity. These hormones stimulate the high anaerobic energy system, resulting in increased lactic acid concentrations. Removal of lactic acid from the muscle cells requires a high rate of blood flow, but as these horses are only doing slow to medium work, blood flow to the muscles is only moderately increased. Due to the slow rate of removal of lactate it accumulates within the muscle cells. The high concentration of lactate within the muscles reduces the capacity of the cells to remove calcium and hence their ability to relax.

CLINICAL SIGNS:

* a characteristically painful, shuffling gait
*
severe cases may be unable to move, or even recumbent.
*
pain may cause sweating, elevated heart rate and rapid breathing - these may be the only signs
* blood tests show elevation of the muscle enzymes - creatine kinase (CK) and AST

CAUSES: The classic case is the horse fed high grain and then given a day of rest, hence the name 'Monday morning disease', however ongoing research has shed a lot more light on the syndrome and its complexity.

Tying up can occur in any horse, but there is wide variation in susceptibility to 'triggering' factors.

Factors known to 'trigger' tying up include:

* genetic muscle disorders
* vitamin E and/or selenium deficiency
* hormonal disturbances
* thyroid disorders
* electrolyte imbalances
* diets high in raw grain which can result in carbohydrate overloading
* viral and bacterial infections
* abnormal muscle calcium levels.
http://www.mitavite.com.au/news_VN_B14.asp
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Old 05-19-2006, 05:42 PM   #7
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The guy that came up with this took alot of heat for the idea. I'm still skeptical, but this:
Quote:
"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.
is making me think twice.

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Old 05-20-2006, 01:41 PM   #8
Martha Castro M.D.
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This is a very interesting article. It explains very well the confusion with the breaking down of glycogen, the storing of glucose in the liver and the carrying of hydrogen by lactic acid out of the muscle cells to impede it from accumulating and in that way allow the hard working muscle to continue to exercise with intensity. That is why, we cyclists, have to learn how to breath properly to be able to bring more oxygen into our body when we bike with intensity to avoid the accumulation of hydrogen in the muscles.

http://www.ultrafit.com/newsletter/october04.html#Joe
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Old 05-20-2006, 11:50 PM   #9
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i worked at the local racetrack vet clinic some 15 years ago and before a race, some horses got glucose iv's with sodium bicarbonate mixed in. when asked what purpose they had, i was told that it changed the ph of the body enough to resist the lactic acid biuld up in the muscles during a race, delaying muscle fatigue for a couple of seconds. for some horses it seemed to work and many trainers swore by the treatment.
at least, this is what i was told....

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Old 05-21-2006, 01:44 AM   #10
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I know something about lactic acid in weightlifting, at least. The pain that you get a day after lifting is called DOMS (delayed onset muscle soreness) and it doesn't have anything to do with lactic acid. It's caused by microscopic tears in the muscles' connective tissue. It usually sets in almost exactly 24 hours after lifting, as long as you lift heavy enough.

Lactic acid burns briefly if it builds up due to the rate of production exceeding the rate of clearing. It only burns briefly, while you're still lifting, and stops a few seconds after you set the weight down because with no more being produced, the leftover is almost immediately cleared from your muscles. Lactic acid burn is the worst with intermediate weight reps. If you're lifting at your 5-rep max, your muscles' power will give out before you get a significant amount of lactic acid buildup. Likewise, if you're doing something like pushups, where you can do 30-40 reps, your muscles aren't doing enough work for lactic acid to be building up quickly enough. Right around 10-15 reps, that's where lactic acid is the worst. You're pushing the weight, and you feel the burn, you know you have the strength to keep going but often it's the pain that makes you stop.
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Old 05-21-2006, 04:53 AM   #11
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Gathercole wrote
I know something about lactic acid in weightlifting, at least. The pain that you get a day after lifting is called DOMS (delayed onset muscle soreness) and it doesn't have anything to do with lactic acid. It's caused by microscopic tears in the muscles' connective tissue. It usually sets in almost exactly 24 hours after lifting, as long as you lift heavy enough.

Lactic acid burns briefly if it builds up due to the rate of production exceeding the rate of clearing. It only burns briefly, while you're still lifting, and stops a few seconds after you set the weight down because with no more being produced, the leftover is almost immediately cleared from your muscles. Lactic acid burn is the worst with intermediate weight reps. If you're lifting at your 5-rep max, your muscles' power will give out before you get a significant amount of lactic acid buildup. Likewise, if you're doing something like pushups, where you can do 30-40 reps, your muscles aren't doing enough work for lactic acid to be building up quickly enough. Right around 10-15 reps, that's where lactic acid is the worst. You're pushing the weight, and you feel the burn, you know you have the strength to keep going but often it's the pain that makes you stop.
It's for these reasons among others that the article sounds fishy. The guy talks about how you don't feel the burn from lactic acid until a few days later. But it's been known for quite some time that that particular pain isn't caused by lactic acid. The pain caused by lactic acid is when your muscles are tired but still doing work.

If it's true that mitochondria somehow use lactic acid as a fuel, then this would really be a revolutionary change not only in exercise physiology, but in general biology. I think it might be the that the writer screwed up or something. Because that sounds really whack. I don't think the scientist referred to in the article would be whack job. He is a professor at Cal after all.
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Old 05-21-2006, 04:54 AM   #12
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But then come to think of it, Behe is a professor at Lehigh U and he believes in intelligent design even though the rest of his faculty don't. So hey, the guy might just have tenure or something.
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Old 05-21-2006, 11:40 AM   #13
Martha Castro M.D.
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Eva wrote
i worked at the local racetrack vet clinic some 15 years ago and before a race, some horses got glucose iv's with sodium bicarbonate mixed in. when asked what purpose they had, i was told that it changed the ph of the body enough to resist the lactic acid biuld up in the muscles during a race, delaying muscle fatigue for a couple of seconds. for some horses it seemed to work and many trainers swore by the treatment.
at least, this is what i was told....
Exactly! Glucose with sodium bicarbonate together promote the retention of H20 in the cell of the muscle, that has a lot of benefits in the working muscles of the cyclist, runner or weight lifting athlete, or the racing horses too. It does change the pH and those muscles can go further. Although there is still a lot of controversy about this because there are more scientific studies to be done, there is no harm in trying to improve your performance taking some legal substances that buffer lactic acid like Creatine. In USA and in Mexico Creatine in legal, but I have heard that in some European countries it is illegal. Maybe because Creatine promotes water retention, in some cases severely if the patient has some renal problem.

Creatine buffers lactic acid, but haven't been able to find anything on it that proves it does. One theory may be the enhanced cellular hydration - The more water your cells are holding, the more dilute the byproducts of anaerobic metabolism may be.

CEE (Creatine Ethyl Ester) is "supposedly" a much better form, with extremely high take-up. Lots of positive anecdotal reports, but nothing studied, yet.

Buffering lactic acid is of interest to me; it's the main villain in decreased performance in sports requiring maximal output.
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Old 05-21-2006, 02:12 PM   #14
baconeatingatheistjew
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Eva, what you described is called a milkshake. The practice is banned in American and Canadian racetracks.
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Old 05-21-2006, 09:44 PM   #15
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all right, bacon....i'll take your word for that.
this was many years ago, maybe they banned it after i was at the track.
however, i remember that it was not allowed less than 48 hours or so prior to the day of the race. have to see if that is still the case....because maybe the ban you mention is only for the day of the race...

One of the most irrational of all the conventions of modern society is the one to the effect that religious opinions should be respected....That they should have this immunity is an outrage. There is nothing in religious ideas, as a class, to lift them above other ideas. On the contrary, they are always dubious and often quite silly.
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