Lactic Acid Update

In this article he argues that lactic acid production from the breakdown of glucose by glycolysis is not the cause of metabolic acidosis because the hydrogen ions are produeced earilier in the pathway.

Peter Hochochka made the same argument in his 1983 paper however the conclusion he came to was, in the end all that really matters is the net reaction which can be simplified to

glucose ---> 2 lactic acid

this concluson is still valid

so during exercise, lactic acid production is the major cause of muscle acidosis

This argument is useless, and deceiving. Lactic acid is produced when the body goes into the anaerobic phase; true. Lactic acid causes discomfort; true. But without lactic acid anaerobic activity would be much less efficient;true. So therefore, lactic acid causes pain and slowing down, but it is a necessary tradeoff considering how impaired anaerobic activity would be without the production of lactic acid as a result of glycolysis.

Of course, Tim Noakes would say:

"Welcome to the Twilight Zone. It really doesn't mantter whether you think that acidosis is caused by lactate or by a proton. The whole thing was invented by your brain to make you think that your muscles are tiring so you stop running so damn fast.

You need to explain to your brain that the redline is actually at 6900 RPM instead of 6750."

priceless. Noakes in a nutshell.

Facts? Who need em?

...hence the Central Governor model of muscle fatigue. Your muscles, and therefore your brain, cause the fatigue themselves. So the root cause of fatigue is the inability of the brain to recruit the needed muscle fibers. Teach your brain to recruit more muscle fibers and you'll do the other things (increase Vo2max, increase lactate threshold, increase running economy) as a byproduct. Instead of thinking in terms of Vo2max, lactate threshold, and running economy, think in terms of specificity.

What is important for a 10k runner? Running at 10k pace. What is important for ANY distance runner? Increasing the maximum ability of the body to do work. The "how" of distance running hasn't changed, only the "why". Why are tempo runs important? It's not because they are run at some level of lactate, it is because they best simulate race conditions (long bouts of hard sustained exercise) without actually racing. Why are intervals important? Because you are exercising your heart/lungs at it's maximum level as well as your MUSCLES. You are running at a high power output. Same reason why distance runners do short sprints, to increase power output. Why are long runs and distance runs in general important? You are increasing the strength of the muscle and the ability of that muscle to contract over long periods of time. The increase in mitochondria density, capillary density, stroke volume, etc, is only a BYPRODUCT of the need to increase muscle force over time.

Personally I like to group workouts into 2 categories: Those that are aimed to improve a certain race goal. Those that are aimed to improve the overall body condition.

1. When you run intervals at a certain pace, take a rest so that you can repeat the interval again without problem you are training to run at that pace. EX: 10x1k @ 10k pace w/3:00 rest, 6x1mi @ 10k pace w/3:00 rest, enough rest to drop HR to level it would be if you were just jogging (say 120-130).

2. When you run intervals at a certain pace, take a rest but NOT allowing the body to fully recover, not allowing the body to repeat the interval without problem but WITH stress, you are increasing the overall body condition by pushing it to it's max. EX: 10x1k @ 10k pace w/1:00 rest, incomplete rest, say HR 190 during interval, drop down to 150 during rest.

3. When you run tempo runs at a certain pace and want to maintain that pace (be it 5 miles at halfmara pace or 10 miles at marathon pace) you are training for that pace.

4. When you run tempo runs without regard to pace over varying terrain increasing the pace throughout the run you are training to improve your overall condition, training to simulate a race. EX: 6 miles starting at halfmarathon pace finishing at 10k-5k pace.

5. When you run hills or short sprints you are running at near peak force production and are thus training to increase force production. This is why hills and sprints work for distance runners.

Any Questions?

Yeah, got any proof for your bullshit theory?

Ooops. No. Sorry. Yeah, I read your book too. You talk it up a lot but the only thing you use to back it up is "it could be" or "it might be". You don't know how the Central Governor works, you've never been able to "observe" it. You don't even know where exactly it IS.

Pathetic.

NONAME,

"If muscle did not produce lactate, acidosis and muscle fatigue would occur more quickly and exercise performance would be severely impaired."

There is research showing that high lactate levels improves performance.

http://www.powerrunning.com/Exercise%20Physiology/Do%20High%20Lactate%20Concentrations%20Actualy%20Improve%20Performance.htm

I don't know what we're all pissing about. This is simple biochemistry.

The anaerobic pathway requires hydrogen ions in order for the sequence of reactions to occur. The hydrogens are formed through the conversion of lactate from pyruvate, thus lactate is referred to as an "ion reserve"

What else is there to argue about?

jtupper knows his stuff.

Lactate doesn't cause fatigue, the hydrogen ions do. Without lactate production, anaerobic glycolysis would stop. The breakdown of pyruvate to lactate allows glycolysis to continue. Plus, lactate can be metabolized once exercise intensity decreases to produce energy.

No where do I discuss fatigue or pH or force production. I was only responding to the article by Robert which discusses where the hydrogen ions come from. Nothing else knuckle heads. And I pointed out that P.H. presented a similar but more convincing argument 20 years ealier and he concluded that the only thing that matters is the net reaction. It is biochemistry, but it is obviously not simple for many of the people on this website.

Sorry, actually I did discuss pH indirectly by mentioning metabolic acidosis however I did not suggest metabolic acidosis did or did not alter muscle force production.

NONAME,

I didn't mean to focus on the source of acidity. Lactate has long been proposed as a source of fatigue (or more recently the H+ associated with lacate as a source of fatigue). The thing that caught my attention in the referenced study was that there is evidence that not only is lactate not a source of fatigue but that it acts to prevent fatigue - meaning that lactate is a good thing.

I need to consider the training implications of this in some detail.

Richard_, you don't seem to get it at all.

Many readers will think the term "Central Governor" smacks of a contrived, all-purpose agent used to conveniently explain away all manners of as-yet-not-understood phenomena. However, the interplay of human biological processes is not completely comprehended, and the unexplained regulatory mechanism (if there is one) needs to be called something until it is explained.

Tying up during prolonged anaerobic exercise provides built-in protection against muscle cell damage and other nasty consequences of low pH. It is likely that if Noakes's "Central Governor" exists, it is within some of the more primitive structures of the brain such as the cerebellum and the reticular formation, which help maintain balance and orchestrate positional changes to produce movement. These brain structures are continuously processing information which is influenced by a host of factors. Even the most simple and thoughtless movements, such as tapping a finger on a desk, require a rather complex interaction of the cerebellum, basal ganglia, proprioceptors, etc. Your volitional thought of "tap finger" is all you are aware of, but to summon the precise motor neurons to achieve the task with the least energy cost is a more complex undertaking than meets first glance.

More advanced movement patterns which require more (or larger) motor neurons require a greater mental exertion, and mastery involves continual practice. When you learned to walk, you fell down a lot as your central nervous system could not yet summon the precise motor units in an orchestrated sequence and the muscles in your feet and legs were not yet strong enough to simultaneously bear your weight and balance it on one foot at a time, yet alone propel you forward. But as an adult, walking is practically a thoughtless activity. You think, "I'll go to the mailbox," and you get up and do it without normally wondering how many times you might fall down on the way. Walking is a low-intensity activity for a normal adult, and it requires many motor neurons which are fairly small and are responsible for posture and finer movement patterns. These motor neurons supply slow twitch muscle fibers, as may be found in the soleus muscle (instrumental in standing). Running, particularly sprinting, requires an enormous mental act of summoning a vast continuum of motor neurons and muscle fibers which involve not only force, but balance, precision and coordination of movement.

You correctly pointed out a distinction between general conditioning and specialized event preparation. In mentioning hills and sprints as increasing force production, it is also worth noting that economy (requirement for less energy expenditure) can also be influenced through the use of hills and a few drills, although I would discourage the use of full-speed sprints during a period of base training until other neuromuscular qualities were acquired. I'll explain the rationale behind that in more detail (and with an analogy or two) if asked, but it goes back to the previous concept that forceful muscular contractions simultaneously require balance and precision of movement in order to minimize energy expenditure. Practicing exaggerated, rapid-fire motions which involve both force (neurons with a high threshold for activation) and stability (neurons with the lowest threshold for activation) will train the central nervous system and all its complex feedback mechanisms for complete mastery of the task at foot. This results in the minimum energy cost and the most efficient forward propulsion.

Regarding the original topic: It doesn't really matter whether the dissociation of lactic acid is immediately responsible for protons which interfere with muscle movement or if those protons are by-products of reactions further down some chain of events. That is to say that it does not make much difference to your training if high lactate production turns out to be the cause of, a consequence of, or simply concurrent with "tying up." What does matter is 1) recognizing that tying up and laboring too often results in inefficient movements, reduced time spent running, feeling stale, and potential cell damage (therefore making many forms of anaerobic training low in cost-effectiveness) and 2) learning to identify physical feedback that signals such laboring is imminent. It so happens that exceeding the lactate threshold is a prelude to the onset of struggling (whether it is the cause of struggling or not). Since blood lactate measurements are now relatively easy to obtain (and can be correlated with heart rate and, in a more subjective sense, with perceived exertion), why not use the lactate threshold as an objective marker for effort intensity? Someday the entire notion that there is a "lactate threshold" may be debated or even discarded, but how you feel during that stage of effort between "in control" and "in trouble" will always serve as an effective training barometer.

So, Richard_, given this marvelous breakthrough in biochemistry, how do we apply it to our training? And how do we integrate the "lactate rules" idea with the "mileage clearly helps, but only so much, so run less" principle?

I suggest doing one of two things. Either go back to inhaling your father's industrial compounds in the garage and let go once and for all of the idea that your spaceshot droning has any merit whatsoever, or quit the WD-40 habit altogether so that once, just once, you might post something that doesn't leave you looking like a beaming mongoloid whose shit-filled diaper has once again fallen down around his ankles.

You may want to read, "My Love Affair With Lactate" in the most recent issue of Track Coach.

Zuzu is right, the new theory still doesn't change how you train and utilize lactate meters. It is still interesting to talk about and ponder the actual reason for fatigue though. This is a very interesting thread. Nice to see.

By the way people keep talking about how pyruvate is converted to lactate to be used as fuel by the mucles. Actually it is the other way around. Lactate is produced by the muscles in relation to the level of glycolysis. Lactate can not be used as a fuel. It must be converted to pyruvate in order for it to be utilized by the muscles. The Pyruvate is utilized in the presence of oxygen, so this is an aerobic process. The aerobic capacity is the limiting factor in the utilization of the pyruvate. So there is such thing as not having enough oxygen to support the activity. Once you can no longer utilize pyruvate as fuel, it is then converted back into lactate. If this continues to occur your muscles will become too acidic, and cellular activity will cease in the muscles, because enzymes can not function in this environment. Ultimately your aerobic capacity is your limiting factor to performance, which is what Lydiard has been raving about all of these years. Lactate is valuable in that it produces energy faster than your other energy sources can. This becomes more significant the shorter and faster your race distance is. This begins the argument of whether a lack of oxygen limits performance or whether Hydrogen ions limit performance. It ultimately comes back to oxygen, because a lack of oxygen in the muscles will start you on the road to high acidity, since a hydrogen ion molecule will be produced for every lactate molecule. You wouldn't be accumulating too much lactate if your muscles could use all of the pyruvate available, and if you had enough available oxygen at all speeds you would not slow down until you ran out of glycogen that is, since glycolysis can not occur without it.

Zuzu,

Well said. The physiological theory is in the process of changing in that we now know that lactate is not a source of fatigue. However, a change in the physiological theory does not change the realities of training.

The thing that may occur though is that a more accurate understanding of what is happening physiologically may lead to some further refinements in training methods. For example, for many years it was proposed that training just slightly below the "lactate threshold" was optimal because it taught the body to work for increasing longer periods of time without accumulating excess blood lactate levels. More recently, in line with our updated understanding of the function of lacate, the suggestion has been that training above the lactate threshold is a better method to train the body to deal with and process lactate.

(

http://www.pponline.co.uk/encyc/0175b.htm

)

Balance,

"It ultimately comes back to oxygen, because a lack of oxygen in the muscles will start you on the road to high acidity..."

I don't have the citation now (I can provide it later when I'm at my home office), but recent research has shown that even at high intensities there is no shortage of oxygen to working muscles.

Regards,

Richard_ wrote: "...recent research has shown that even at high intensities there is no shortage of oxygen to working muscles."

Really? Then why would anyone dream of using EPO? They've got a needle fetish?