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Is Lactic Acid the only culprit in muslce soreness?(10 posts)

Is Lactic Acid the only culprit in muslce soreness?SilentBob
May 2, 2002 10:13 AM
As for muscle soreness, everything I've read points to a build up of Lactic Acid, until I read this article. I know everyone has a theory of why everything happens, but I was just curious about what some of the hardcore nutrition guru's on this board think (ie. like LFR, ColnagoFE, peloton, etc.)

http://www.clifbar.com/sports/trainingtips/exercise/exercise2.html
I'm buying it (the micro-tear theory). nmbill
May 2, 2002 10:36 AM
nm
I partially agree...SilentBob
May 2, 2002 10:47 AM
I understand the micro-tear thing. That's how they say mucsle become stronger. Micro-tears, then the muscle heals stronger; yadda yadda yadda. I'm just wondering what role Lactic Acid plays in everything then. Why is it that when I train, knowing my AT is so important, in order to increase it? Etc.
I partially agree...weiwentg
May 2, 2002 11:00 AM
lactic acid has NOTHING to do with soreness at all. if I'm not mistaken, it inhibits energy production in the muscle cells, that's all.
I partially agree...RockyMountainRacer
May 2, 2002 11:10 AM
The key is that you need to increase your body's ability to buffer and remove lactic acid from your blood during exercise. Lactic acid build-up in the blood is what causes you to "blow up" when you are hanging on to the pack for dear life and trying to respond to attacks left and right. Lactic acid greatly impairs the muscles ability to contract and the neurons ability to send the signals for contraction.

Therefore, it is highly important to raise your lactate threshold. This threshold is where lactic acid begins to rapidly accumulate in the blood because you are reaching beyond your bodies ability to buffer the acid. If you can raise the level of exertion where this occurs, you will be able to go faster, longer. Example: you did your anaerobic intervals and LT intervals and you have raised your lactate threshold. Your buddy did not. You attack him up a hill and incrase the pace. Since your LT is higher than his, you can go faster for a longer period of time. This causes him to blow up and get dropped.

You can increase your LT by doing intervals of exertion at or above your lactic threshold (your anaerobic zone). Unfortunately, this level of extreme exertion is what causes the most muscle damage (the micro tears Burke talks about in the article). This is why you must be patient with your high-end development and allow yourself time for recovery after these workouts (or races). If you don't heal from these efforts, you won't get faster!
Ah... I see said the blind man to his deaf wife...SilentBob
May 2, 2002 11:58 AM
Cool. Thanx for the info.
Lactic acid has gotten a bad rap...Wayne
May 2, 2002 2:43 PM
It's not clear that lactic acid causes you to "blow up", it's clear that you are producing alot of lactic acid when you blow up, but you're also producing alot of other metabolites (inorganic phosphate is probably a bigger factor in slowing you down than lactic acid). BUT lactic acid is easy to measure because it's going into the blood. It's the old problem of confusing correlation with causation. Furthermore, 20-30 years ago, there were studies that showed that lactic acid inhibited force production in muscles, so it was a nice story: you go hard, glycolytic rates increase to meet ATP demands, you outstrip the aerobic ability of your muscle cells to convert lactic acid into oxidizable pyruvate, the lactic acid builds up, excess gets dumped into the blood, your legs burn, you have to slow down, etc. etc. But there were limitations to these early studies and with better techniques that allow for testing at physiologic temperatures it appears that lactic acid does not inhibit force production, furthermore, there are persons with McArdle's disease that lack one of the enzymes necessary for production of lactic acid (consequently almost all of their cells ATP demands must be met by oxidation of fats, since they can't produce lactic acid to convert to pyruvate their ability to produce ATP from glycogen either "anaerobically" or "aerobically" is severely limited), Guess what? They show extreme exercise intolerance, with reports of burning/cramping muscles! Hard to blame lactic acid in this case.
Yes, as you become fitter your LT changes, but remember what this is? It's basically a measure of your aerobic capacity.
Riders who are stonger aren't stronger because they produce less lactic acid, they produce less lactic acid at a given power output because they have a higher aerobic capacity and can meet their ATP demands largely aerobically without relying too much on glycolysis.
It's probably a combination of metabolites that limit your power output or maybe just your peak ATP production rate (which would be a combination of your peak oxidation and glycolytic ability).
As far as muscle soreness goes, I'd go with the muscle damage theory from high forces (or high forces applied in a certain way). How come a pro bike rider can race for 6 hours placing a high metabolic demand on his quads and do it tomorrow with little soreness, but an elite marathoner can only race for 2 hours and his quads are a wreck for a week? It's because cycling is almost an entirely concentric motion (your muscles contract as they're shortening), whereas running forces your quads to contract eccentrically (as they're lengthening), the latter is acually less metabolically demanding than concentric contractions but produces much greater damage and soreness.
Lactic acid has gotten a bad rap...peloton
May 2, 2002 9:04 PM
Wayne is right on. Lactate is your friend. It's great food for the liver during exercise, and it actually helps to get free radicals out of your muscles. As the muscle doesn't recieve enough O2 for aerobic energy to use pyruvate in the Kreb's cycle it becomes lactate. When it becomes lactate, it picks up a couple of H (a free radical) molecules. This can help to prevent cell damage, as H concentrations in the cells is increasing due to O2 consumption from your RBC's.

Lacate clears from your muscles pretty quickly too, and isn't responsible for soreness after exercise. That's from interuptions of your Z lines in between the sacromeres, and other micro-tears in the muscle fibers. Primarily from eccentric movements, as Wayne also pointed out.

Lactate is your friend.
Lactic acid has gotten a bad rap...Jon Billheimer
May 3, 2002 8:54 AM
I'd just like to add to Wayne's excellent remarks that not only is lactate not responsible for its alleged deleterious effects, but that it is used by surrounding muscle fibres as aerobic fuel, taken up and converted back to pyruvate, then oxidized. A significant element in the lactate threshold equation as fitness increases is the ability of muscle cells to clear and transport lactic acid for fuel. This is facilitated by the body's enhanced production of a transporter protein called MCT-1. As a result of super-threshold efforts, production of this protein has been observed to increase by up to 80%, thus enhancing the muscle cells' ability to pull blood lactate into the cell for oxidation.
nothing new there...greg n
May 2, 2002 1:47 PM
except I do believe without proper cool down, lactic acid remains "trapped" in the muscles for longer than the 60 minutes that the article states. I'm no doctor though, just my opinion.