Discussion: Lactic acid

Can someone with a background in exercise physiology tell me whether this New York Times article correctly describes current thinking about lactic acid? (One sentence summary: lactic acid good; training you used to do trying to avoid lactic acid still good because you misunderstood what it was doing to your body; free registration to the NYT is needed to read the article, or use BugMeNot.)

Well, my informed read of the article confirms what I always knew: radioactive lactic acid is the key.

I said 'someone with a background in exercise physiology', not 'someone with knowledge of shady areas of exercise physiology'.

You get what you pay for. Ask Balter about this.

Another article on the same subject. I haven´t read the NYT yet, but it sounds like this would be along the same lines...

So, lactic acid isn't a waste product but fuels the muscles? Makes me think of Woody Allen's Sleeper:

YOU MEAN
THERE WAS NO DEEP FAT ?

NO STEAK OR CREAM PIES
OR HOT FUDGE ?

THOSE WERE THOUGHT
TO BE UNHEALTHY,

PRECISELY THE OPPOSITE
OF WHAT WE NOW KNOW TO BE TRUE.

It is just a form of alcohol! Vlad proved long time ago that alcohol is good for orienteering.

Is any of this news? It's what I learned 30 years ago in high-school biology class. Lactic acid is an intermediate step in the Krebs cycle, and it's being created and processed all the time. It's just that glycolysis, which is the first section of the Krebs cycle, can happen very quickly (though it doesn't produce as much energy as the rest of the cycle). So for short-term exertion, a lot of glycolysis occurs, and the lactic acid builds up. Back off some, and the rest of the reaction has a chance to catch up. For long-duration exercise, you want to operate at a level such that the lactic acid isn't accumulating faster than it can be broken down. But the reaction that processes the lactic acid is responsible for 94% of the muscle energy. (Or at least, that's how I remember it.)

and cheseburgers.. vlad had 2 beers the night before the 24h rogaine, barely any calories on the first 12h lap, then a big old cheesburger before heading out for a much faster 12h lap... that should throw just about every nutritionist off...

I always feel really hesitant to write something like this, because the subject is complex and debated, so my answer can be disputed…

From what I learned in college the article has some truth, but also makes some mistakes.

Basically, lactic acid is produced when glucose in the absence of oxygen is used for energy. This lactic acid can be reabsorbed by other muscle fibers (usually muscle fibers that are not being used) and the heart muscle, and used for energy. In this sense, lactic acid is NOT all bad, and can be a contributor to the energy used for a given intensity. This means that if the intensity of exercise is at a level where lactic acid is being produced, but the body can break it down (by expelling metabolic CO2) and use it for energy in other muscle fibers, there is no build up of lactic acid in the blood, and performance is not compromised. This is known as the lactate threshold.

On a side note, metabolic CO2 is produced through the buffering of lactic acid is than expelled through our exhalation; this is the reason breathing frequency and volume of ventilation increases with intensity, in order to expel metabolic CO2 and keep a ph balance in our blood.

Where the article over exaggerates a little is in the concept of the lactic acid not being a negative factor to performance. The actual occurrences of when lactic acid is produced at a rate higher than it can be either a. used in other muscle fibers or b. expelled through our exhalation does becoming a limiting factor to performance. At intensities which are over the lactate threshold, lactic acid does decrease the muscle ability to contract and continue working at the given intensity.

This is why two types of intervals are important. First, intervals *at or just below* the lactate threshold teaches your body to use the lactic acid that is being produced and stay in a ph balance. This is the type of intervals that build endurance, stamina, it is basically a rehearsal for the speed at which competitions are performed at, and are an important part of a training routine. These types of intervals are longer in duration (2 min +) and have shorter recovery time than the interval time itself. The total volume of intervals can range up to 20-30 minutes depending on fitness levels. This is also a speed and intensity that does not (necessarily*) increase the risk of injury, and should be a pace that can be held up to 30-40 minutes.

The other types of intervals are *above* the lactate threshold. These types of intervals are what makes it possible to increase the speed of your lactate threshold. But have a bigger impact on the body, and increase the risk of injury. This is why it is very important to build first your overall endurance with long slow distance running, than work at your threshold speed in order to build the stamina needed to do intervals at intensities over the lactate threshold. These types of intervals are short in duration (no longer than 2 minutes) and recovery time is longer than the interval time. The overall volume of such intervals should be small (<10 minutes). Blood lactate levels increases during the intervals, and stay increased during the recovery. This is why they are good at training the body to buffer blood lactate. These types of intervals also stimulate fast-twitch muscle fibers, help develop neuromuscular coordination and enhance muscle recruiting patterns.

Something important to remember: if you complete intervals over the threshold, and subsequently (hopefully) your overall speed and endurance improves, this means that the speed of at your lactate threshold will also increase. This is where it gets tricky, since most people do not have access to getting a lactate threshold test, and especially not twice a year, this type of development is basically dependant on the athlete’s judgment of their progress in their fitness. Heart rate monitors are a good way to judge improvements in speed and fitness, and doing intervals on specific routes where distance can be controlled for and used for comparison also helps. Don’t forget heart rate can be altered by many different factors; caffeine, amount of sleep, stress levels, and onset of illness all have influence on your heart rate.

On a side note: The article makes the mistake to say that when the intensity is aerobic that glucose is being used for fuel, which is not really true, at an aerobic intensity the main substrate being used if fat!!

Does that answer the question? This subject is pretty complicated and there are dozens of theories about the best way to train, the best intervals to do, and why. Doug Mahoney could answer this much better. Doug if you read attackpoint please correct and improve my answer.


*please take what I am writing not as the absolute truth, and always listen to your body! Take what I wrote with a grain of salt.

Vlad's cheeseburger-enhanced performance might confuse a nutritionist, but it certainly won't surprise most ultra-endurance athletes. As Sandy pointed out, at sub-threshold levels, fat is the primary fuel source. I eat plenty of it in adventure races.

BugMeNot! That's genius! I can finally start reading the NYT again!

Hmm... This time it let me read the article you linked to without logging in... Maybe the NYT is finally coming to it's senses?

OK, betraying my ignorance, why is it so hard to read NY Times stories? You need to log in, yes, but is is free, right? What do you need bugmenot for?

Some people don't like logging in to these kind of sites as a matter of principle. Others just use false data and create a login. I personally tend to use real accounts on sites I visit often and BugMeNot on rarer beasts (in Firefox you just right click on the 'id' box and select BugMeNot, and it gets filled out for you, which is much easier than entering it yourself even if you actually have an account). If you barely ever read a particular site, it's not worth registering and getting yet another password, so BugMeNot just lets you 'borrow' someone else's login and password for the purpose. Plus it screws up the company's data collection a little, which serves them right for trying to collect the data in the first place.

On the second comment above, were you still logged in from a previous log in (kind of implied by 'This time...')?

Does your aversion to doing this stem from being an economist?

I guess I don't understand what principles are involved (unless we're talking about pornography rather than the NYTimes :) It seems like a trivial quid pro quo for the privilege of reading the paper, production of which requires substantial factor inputs. Granted, reading some papers may not be a "privilege," but this is neither here nor there... Anyway, I'm sure your university library has Factiva or the like which allows for some sort of implicit payment for the value of the services you are consuming.

Yes, fat. I remember 4 years ago at the 5WRC I kept eating PowerBar(f)s and all, and after we finished, for about 2 days I felt like a 70-year-old. Now that I am actually a 70-year-old, I can eat all the cheeseburgers I want and drink beer, and feel not a single bit older.

Gee - what does a 70 year old feel like?

szurcher, I would probably comment that you are only partially correct, whilst it is true that lactic acid accumulates with high intensity exercise what is now being debated is whether it actually does decrease the muscle's ability to contract.

It has long been assumed that it does just because lab measurements show that as lactic acid accumulates muscle fibre contractivity decreases, however just because two things happen together does not prove causality.

For example during Summer icecream sales increase and at the same time sales of firewood decrease. Does this mean that increasing sales of icecream causes a decrease in sales of firewood?

In more recent studies (I can try to dig some out if you want) it has been shown that muscle contractivity actually increases or at least stays the same with greater concentrations of Lactic Acid (but in the absence of other muscle metabolites which build up with fatigue) so it appears that it is NOT lactic acid but possibly increasing Calcium concentration or more likely a combination of factors which leads to the decrease in muscle contractivity.

Despite this in almost every Exercise Physiology 101 class everyone is taught that lactic Acid causes fatigue BUT things are starting to change.

@feet: No, I have never logged into the NYT. I stopped reading them when they started requiring an account. I still haven't used BugMeNot, but I have it bookmarked for the next time I am trying to read something on Google News and a site asks me to sign up. I have no idea why I was able to read that particular article on the NYT site without logging in. None of their other articles work...

@j-man: I like to use Google News to get links to articles from all kinds of different sources. That way I can get a better idea of both sides of a particular story. No matter how unbiased any single news agency tries to be, it is impossible to really get the full picture from one source. Google News gives you many different sources for any headline, but when sites start forcing you to sign up in order to read their articles, it makes this process very laborious. Fortunately, most sites don't require this yet, so I simply skip over the ones that do. But BugMeNot makes it possible to quickly log into any site without having to go through the process of signing up.

Anyway, back to the topic...

we would die very quickly if we could not produce lactic acid. so its good.

but it is implemented in fatigue, mainly the proton (not the lactate anion). but then so are quite a few different things. as candyman points out, calcium, changes in calcium homeostasis and changes in calcium sensitivity are often an issue. but changes in pH, oxidative stress and central metabolites (ADP, ATP), fuel availability and presence, oxygen etc are likely to cause these in the first place. but its much more complex, and not well understood beyond that.

Hamburgers are a major part of Thomas Alsgaard's diet.

No wonder that some Ukranians are so good in orienteering! Their main diet is pork fat and gorilka (ukranian vodka) :)

Chouette! I was able to read it too. Thanks Mister Fredrickson for pointing out I could read it without login, otherwise I would have never read it and would still think lactic acid is the devil ;-)