???
The only context I’ve heard lactic acidosis used in is medical. It implies that so much lactic acid is produced, that it changes the blood pH. Common causes are shock, cardiac arrest, acute fluid build-up in the lungs, and carbon monoxide poisoning.
I found a mention of severe exercise producing lactic acidosis, but i don’t think that’s what were talkin’ 'bout
Thanks to Soup-, Ogre, and Choosybeggar on this thread. Soup for posting it, Ogre for giving me a link, and Choosy to explain why I get the burn when I do the exercise slowly, holding for a count of 1 or 2 at the end of the eccentric motion. I’ve always wondered about the burn too, but assumed that it was the blood.
I’m back. I’ve been mulling this over and I’m not convinced inspite of all the posts and links to authority. I have not read anything with documentary evidence of lactic acid causing the burn. I’ll tell you why I have my doubts.
I’ve done many long runs, long races, marathons, and even an ultra and never experienced any muscle burning. I’ve hit the wall, running out of glycogen, and felt fatigued. But I’ve also accumulated much lactic acid in my leg muscles, and got “thunder thighs.” My thighs just would ache when I tried to lift them. But, you say, those are mostly aerobic stuff and weight lifting is largely anaerobic. However, I’ve done speed work, intervals, etc., and never felt any burn either.
So I’ve built up plenty of lactic acid, much more than a set of reps could produce. I’ve exhausted my myoglobin of oxygen. I’ve never felt any burn except when I do weights. In addition, I notice that when I feel the burn, I can see the blood flowing through the muscle (by way of its redness).
Explain that to me or, in the alternative, give me a link to some documentary evidence, and I’ll be convinced.
HAPPY NEW YEAR.
This looks like a good site: LINK Follow the muscle physiology link on that page.
Check out the bottom third of the page. There’s also a very nice graph. It reminded me about Creatine Phosphate, which is a very short term, high yield energy source stored in muscle.
I think it clearly states that long and slow exercise (marathons and such) rely on long and slow energy production (aerobic, using glucose and fatty acids as substrates). There’s no lactic acid buildup with aerobic matabolism and that’s why there’s no burn with this type of workout.
Short and intense (weightlifting) on the other hand, relies on high-output, short tern energy (creatine phosphate-no lactic acid, but also anaerobic glycolysis-lactic acid production).
So far I haven’t found something like “we infused lactic acid into a resting muscle and are reporting the sensations of the subjects.” That would settle things and who knows it may be out there. i’ll keep looking.
Thanks for the link Choosybeggar. As an aside, let me note that the main link states that exercise intensity will not be reduced during long, slow events since the body can use glycogen, fats, and proteins as substrates. However, a subsidiary link states that since glycogen depletion occurs, exercise intensity will be reduced dramatically. As any one who has run a marathon knows, that is the case. That’s “hitting the wall.” Fat and protein metabolism is too slow to prevent that.
As for “there’s no lactic acid build up with aerobic metabolism,” that may be true enough, but there is no exercise which is purely aerobic. Even a slow pace is somewhat anerobic. I have read a lot about marathons and marathon running and I have no doubt that a lactic acid build up does occur in marathons.
Dear choosy: from webmd.com:
“Lactic acidosis occurs when lactic acid accumulates in the blood stream
at a faster rate than it can be eliminated. Lactic acid is produced in the
presence of decreased oxygen. The most common cause of increased
lactic acid is intensive exercise in which the body builds up an oxygen
debt.”
Handy,
I guess my point was I think of lactic acidosis as a clinical condition; something that when discovered you’d try to do something to treat it. This implies that the magnitude of the acidosis would be such as to produce overy clinical manifestations. I totally agree that exercise will produce lactic acidosis in a formal academic sense (you exercise, you make lactate, it’s there, right?) but rarely in a clinical one.
I’m curious what the full-fledged MDs on the board will say, but when I hear acidosis, I think blood pH below 7.35. I wonder what intensity of exercise we’d be talking about to acheive this. My ref (Rose’s renal physiology book) cites SEVERE evercise as a cause of lactic acidoisis. My interpretation is that Rose means clinically relevant lactic acidosis.
Anyhow, I think that our main difference is semantic.
barbitu8, perhaps in weight-lifting you are also experiencing micro-tears in the muscle whereas you are not during sprinting. Do you get the burn when you do squats, or just upper body work? It could be that your legs are in such good condition that they are acclimated to lactic acid accumulation. Or it is also likely that you are not experiencing much sustained overload when you are sprinting as opposed to squats or other weight lifting.
Muscle tears I can believe as a possibility for the burn, but I doubt it. That’s the cause for DOMS (delayed onset muscle soreness.) However, I refuse to believe that lactic acid is the cause, unless it can be proved to me. BTW, I only feel the burn in the quardriceps when I use the quadriceps machine (the sit-down, raise legs with toes under the bar). I sometimes feel them in the hamstrings machine, but I’ve never felt them any where else.
One other point I should have mentioned. It has been conventional wisdom for lo these many years that a marathoner should jog easily (or swim or do anything with a light level of exertion) the day after the marathon to get the blood flowing, thereby helping to remove the lactic acid build up. I’ve also read somewhere the different percentages of aerobic metabolism vs. anaerobic metabolism for different levels of effort. For example, all out sprinting is nearly 100% anaerobic, but even an easy jog has some anaerobic component. Further, when I race, even such a long distance as a marathon, I’m putting out over 70% effort. And I race many short distances when I’m putting out 90% effort. There’s quite a lactic acid build up there. BUT NO BURN
I have quite a few bookmarks under “Running” and I’m going to search through them for something to uphold my position, that it’s the blood.
I can’t imagine why the lactic acid would stick around this long. Think of lactic acid as a small molecule that gets taken up by the blood stream by virtue of diffusion. All the lactic acid should be cleared locally on the order of minutes (an hour or two at most) post exercise. Thinking that lactic acid would hang out for a day or so is akin to thinking that the carbon dioxide produced by respiration hangs out for a day or so.
Why light exertion? I dunno. There may be a very good reason to do this, I just can’t imagine it to have anything to do with lactic acid removal.
barbitu8,
I found this article. Sounds like it addresses pain causing factors during exercise. I can’t get b/c it’s not online and our library isn’t open. But the abstract says:
Pain perceived during exercise is considered to result from a combination of factors including acids, ions, proteins, and hormones. Although it is commonly believed that lactic acid is responsible for this pain, evidence suggests that it is not the only factor. However, no single factor has been identified.
Exercise-induced muscle pain, soreness, and cramps
J Sports Med Phys Fitness 1994 Sep;34(3):203-16
Way to stick to your guns. I’ll try to get the article (unless you have easy access).
Thanks very much chooseybeggar. I don’t have easy access and I would appreciate reading at least a summary of what it states. I guess lactic acid is a factor then, but it’s not the sole factor. The OP thanked everybody for the quick response to his question, but a quick response is not necessary the correct response. I guess it was the thinking that lactic acid is the cause, just like it has been the thinking that easy exercise the day after the marathon rids the body of lactic acid. I always wondered about that too, as I thought the body would convert it back to glucose quite quickly.
Most of the stiffness and pains the day after the marathon is caused by DOMS. I don’t know why easy exercise would alleviate that. It may help for reasons we don’t know, but it never hurts.
Let me toss in my $.02 here. I’m 49 and about two years ago decided after almost 30 years of sitting on the couch to get back into shape. I decided to buy a mountain bike. When I first got the bike after one block (two if downhill) I felt the burn. boy did my thighs burn. Now two years later I can ride all day and not feel the burn, fatigue yes, burn no. The only way I can get the burn now is to either do interval training, lower my seat or stand and sprint. These things cause me to use my muscles in a different way and I can still get the burn.
Barbitu8, I think that you are in too good a shape, is why you don’t feel the burn.
My quadriceps, which is undoubtedly my strongest muscles, are the only ones that feel the burn when I do the strength trainining thing (occ. my hamstrings which are probably the 2d strongest). I have never felt a burn when exercising (other than weights), even when I first started to run about 25 years ago. Pain, tightness, stiffness,“doms,” fatigue yes, but burn no.
barbitu8,
I have to wait for interlibrary loan. Will report back when info arrives.
Here’s the straight dope on muscle pain during exercise. According to the article I cited above:
I always wonder how an orthodoxy develops in the absence of data. Great call barbitu8 for holding out on lactic acid.
Thanks very much, Choosy Beggar. I knew you would come through.