Lactic acid

[LauraPaura]

I've been wondering for a long time now wheater or not I get that in my legs. The problem is that I don't know how it feels! Is it that slight burning sensation or is it the feeling when suddenly your legs fell like they weigh about 100 kg each or what? And if I get the acid is it still ok to keep on going?

This popped into my mind when this Fininsh guy who was expected to win a gold medal in Torino used this as an excuse to come in 9th instead of winning :o

[tattiefritter]

Not an expert on this by any means but I always thought it was "The Burn", i.e when going up that steep hill and your legs feel as if they can't go on anymore (in my case usually accompanied by me trying to breathe in through every possible orifice before I pass out). As far as keeping going I think its fine if you can keep it going. Sometimes I can keep going and push through it and the burn subsides quite quickly once I return to easy spinning, sometimes I can't (usually steep offroad stuff) and I have to stop or keel over.

[Veronica]

Lactate acid is building up when you feel the burn. It's okay to ride through it. The more efficient your respiratory system is, the quicker you can rid of it. I can usually get rid of mine with a minute or two of easy pedaling. Thom gets his at about mile 60 in any ride - no matter how easy or hard the ride - and he can't get rid of it. I think a lot of that is genetic.

V.

[Melody]

Hi Laura. :) I wanted to clear up a couple of things.

Firstly, our bodies don't produce lactic acid but instead produces lactate, a very important form of energy. The lactic acid production was widely believed to be true for over 60+ years but as we've learned more about how the body works this has been debunked. :)

What occurs in our body and exertion increases is we begin to rely more heavily upon the lactate created in our bodies. The lactate itself is broken into glucose which is used by the bodies under strenuous activity.

What causes decreased atheletic performance is the production of protons caused by the breakdown of ATP by the muscles during exercise. This production of protons is kept in check until we meet a threshold (normally called lactate threshold) where our oxygen demands outstrip supply. This begins a buildup of these protons in our muscles which increases acidity (acidosis) within them... which is that burning sensation you get from strenuous exercise. Eventually you will have to stop - there is no choice... or at least slow down until your demand for oxygen stops outstripping supply.

When your legs get to the stage of where they feel like they weigh a few ton each this may be caused by two things. It *could* be acidosis. However it's more likely that your glucogen stores have been depleted and that you need glucose.

You could try this experiment. Next time you feel like your legs just have nothing else, stop for 15 minutes then get back on the bike. Track the time to see how long it takes before your legs feel like they have nothing else again.

At a later date try this again but take some form of fuel with you that's high in glucose. I personally use Gu. When your legs give out and you stop, take some of this fuel and wait 15 minutes then get on the bike. Again track the time to see how long it takes before your legs feel like they have nothing else again. I'm betting that you'll have more energy this second time around using the fuel. :)

Lastly, don't forget those salts! It's one of the things many atheletes don't even think about but it's very important. Your body loses salts as you exercise. In addition to Gu, I also carry bananas with me to eat mid ride. :)

Mel

PS: When you take in fuel, especially a gel like Gu, it's very very important you also take in water.

PPS: References:
http://en.wikipedia.org/wiki/Lactic_acid
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15308499&query_hl=3&itool=pubmed_docsum
This one is about running but still applies to cycling: http://www.time-to-run.com/theabc/lactic.htm

There are others but I'm having search issues at the moment.

[CR400]

I understand that Lactic Acid is almost always present in the blood to some extent. You get that burning feeling in your legs when Lactic Acid starts to be produced faster then your body can buffer it, or clear it out of the muscles. Here is where you will also encounter a term called Lactate Threshold in most cycling circles or training books. Basically it is a heart rate at which your heart cannot beat fast enough, or get enough oxygen to clear the lactic acid without feeling the effects of the acid.

The harder you push beyond this point the more your legs will burn, it can at times get so intense that you feel you need to stop. In my own case if I slow down for just a few minuets maybe 2 or 3 I can go back up to this pace. Each persons body clears lactic acid at a different rate. There are other times that I'll push through and after a little while I'm fine to continue at that pace for a while. Remember just because you are at the point of the burn does not mean you have to stop. If you have trouble getting your breath then you need to slow down. Depending on your goals as a cyclist this can be a zone you want to get close to or exceed in training at least once a week but not everytime out.

Oh as far as the heavy legs I don't know because I don't have that happen.

[Brandi]

Can you have lactic acid build up in your toes? I have had this problem for years. When I do a lot hiking r long bike rides my toes hurt, burn is more like it. I have proper shoes,footbeds and all. anyone?

[alpinerabbit]

Firstly, our bodies don't produce lactic acid but instead produces lactate, a very important form of energy. The lactic acid production was widely believed to be true for over 60+ years but as we've learned more about how the body works this has been debunked.
What occurs in our body and exertion increases is we begin to rely more heavily upon the lactate created in our bodies. The lactate itself is broken into glucose which is used by the bodies under strenuous activity.

http://www.time-to-run.com/theabc/lactic.htm
Another misconception is that lactate is responsible for acidifying the blood, thereby causing fatigue. To the contrary, lactate is actually an important fuel that is used by the muscles during prolonged exercise.

I am not really sure if you as well as the webpage quoted are trying to be funny or not.

Lactate is nothing else than the deproteinated form of Lactic acid. I am not biochemist enough to know exactly what metabolic cycles myocytes go into if high energy demand is not matched by oxygen delivery (or how knowledge has changed since I toiled through the textbooks), so I will leave that open to debate. The fact remains that during strenuous exercise, lactate concentrations rise measurably, with a concurrent loss in performance but to say that the first causes the second would be a post hoc argument since I am not the specialist.

Lactate is a molecule with 3 carbon atoms and cannot be broken down into glucose, which has 6 C atoms.
The liver can turn lactate into glucose again but the cori cycle actually consumes energy.
http://web.indstate.edu/thcme/mwking/gluconeogenesis.html

The debunking mentioned in your third link probably alludes to the theory that stiff/sore muscles do not come from lactate, but are these days thought to come from microlesions in the myocytes (muscle cells).


What causes decreased athletic performance is the production of protons caused by the breakdown of ATP by the muscles during exercise. This production of protons is kept in check until we meet a threshold (normally called lactate threshold) where our oxygen demands outstrip supply. This begins a buildup of these protons in our muscles which increases acidity (acidosis) from the dissociation of the lactic acid produced into lactate and protons; ATP is continuously recycled. The stash of ATP in the cells is limited.

When your legs get to the stage of where they feel like they weigh a few ton each this may be caused by two things. It *could* be acidosis. However it's more likely that your glucogen stores have been depleted and that you need glucose.Indeed, the powerless feeling seems to me from personal experience to come from simple lack of fuel, while the burning will go away with a bit of rest.


Sorry to be a know-it-all, being a considerable noob to the realm of cycling, but I do have a degree in biology. Textbook knowledge admittedly, when it comes to biochemistry.


Dunno about your toes there, Brandi - my feet hurt from being restricted in tight cycling shoes or hiking boots.

[Dianyla]

Can you have lactic acid build up in your toes? I have had this problem for years. When I do a lot hiking r long bike rides my toes hurt, burn is more like it. I have proper shoes,footbeds and all. anyone?
This sounds a little more like a neurological problem, which could be a footwear fit issue or possibly a circulation problem. You might try searching around on terms like "hot foot", neuropathy, neuroma, etc. to read more up on these types of problems. :)

[Melody]

Sorry to be a know-it-all, being a considerable noob to the realm of cycling, but I do have a degree in biology. Textbook knowledge admittedly, when it comes to biochemistry.

alpinerabbit, no problems. :) I'm only quoting from knowledge I've gained which is all lay knowledge and I don't have a degree in biology. Computer work and physics is my expertise. And my physics knowledge (did ionospheric research in college) is mostly old and mothfilled. ;) :)

Mel

[LauraPaura]

Thank you all so much for the replys. I still have to wait a couple more months to get outdoors with my bike (I hate riding in the snow) and try out the 15 min brake because in a spinning lesson that just wouldn't make any sense :)

I have noticed though that when I take one song easier with lighter pedalling I will "recover" and am then able to drive as hard as beofre if not even harder! So there's like this obstacle and once i'm over it it's all good :)

I had to read the texts about two three times before I was able to completely understand it since English is not my mothertongue and it was all this scientific stuff. Luckily I study at the moment in English stuff like chemistry and mechanics so this is all very good practise for me in that sense as well :D I might still read it couple more times just to be on the safe side ;)

[CR400]

Well, keep up the good work with the studies. I know that I could have never understood all the science in the text if it was written in Finnish, or likely any of it for that matter. I tend to think that we don't really teach our kids enough about other languages in the States we just assume and expect everyone to speak English, which is arrogant.