Can Someone Give Me A Clear Description of Lactic Acid as it Relates to Tempo Runs

So lactic acid or lactate is produced when there's not enough oxygen around to break glucose down aerobically. But contrary to what many believe, lactate doesn't produce the pain we experience during intervals or the next day. The real culprit are hydrogen ions, also a biproduct of anaerobic metabolism, which essentially are changing the pH in the muscle cells which they don't like. Muscles, and our entire body really, function in a very narrow range of pH.

The reason we thought it was the lactate was that it was the most easily measured chemical, but the hydrogen ions actually were elevating in sequence with the lactate. We actually use the lactate later on to produce energy through another pathway which was why many physiologists began to question that lactate would cause discomfort....it didn't sit well that an energy source would be inhibitory in any way.

So when you improve with interval workouts what you're actually doing is enhancing your muscles' ability to buffer against changes in pH.

It's still fine to refer to lactate threshold though since we still can use lactate as a metric of the muscles acidity.

I tell my athletes to think of their muscles as a bucket with a hole in the bottom. As we run fast we are dumping more acid into that bucket....producing more and more hydrogen ions (and lactate), and the hole in the bottom is draining that acid away. As we train, we make that hole larger and larger so that it can drain more acid.

Hope this helps.....

So you say that lactic acid/lactate does not cause the burning sensation, rather the free H+ ions do so. Basic chemistry tells me that lactic acid IS lactate with an extra H+ ion.

The hydrogen ion concentration and lactate concentration should produce a proportional (not equal) value. Our body does not "produce" H+, they are popped off from the lactic acid that we produce.

I believe that lactate transports H+ across the cell membrane and into the bloodstream. Within the cell, H+ increase is not due to excessive "lactic acid" production.

Oedipus Rexing wrote:

So you say that lactic acid/lactate does not cause the burning sensation, rather the free H+ ions do so. Basic chemistry tells me that lactic acid IS lactate with an extra H+ ion.

The hydrogen ion concentration and lactate concentration should produce a proportional (not equal) value. Our body does not "produce" H+, they are popped off from the lactic acid that we produce.

Basic chemistry is wrong. Read this paper please:

Northern Star, great citation. Was the one I was looking for.

Their explanation at the end was better put than my fumbling:

"Thus increased lactate production coincides with cellular acidosis and remains a good indirect marker for cell metabolic conditions that induce metabolic acidosis. If muscle did not produce lactate, acidosis and muscle fatigue would occur more quickly and exercise performance would be severely impaired."

So, we are ultimately trying to 'buffer' lactic acid? I know that is the old cliche description, but, is this accurate?

Does the old-school idea of sodium bicarbonate intake hold true value?

endurancenerd wrote:

So lactic acid or lactate is produced when there's not enough oxygen around to break glucose down aerobically. ....

Actually lactate is produced when there's plenty of oxygen too. Lactate is an intermediary product of aerobic respiration.

Can somebody give a progression of what types of energy processes are taking place at different intensities?

Getting back to how the lactic acid relates to tempo runs . . .

The lactic acid concentration is the indicator of the limit of our aerobic metabolism. As we approach the limit we have to increase the rate of anaerobic glycolysis to continue increasing the speed. Think of the anaerobic glycolysis system as needing to rely on a credit card because your monthly income can't cover the monthly expenses.

The tempo run has at least several benefits. One of which is to simply practice running fast, which will improve running economy and let us run faster on the same metabolism rate and type. Another is the strengthening of the cardiac and pulmonary muscles to get more oxygen to your skeletal muscle cells, which will allow the same amount of metabolism to be supplied more aerobically or greater amount of total metabolism.

In my opinion, and the way I like to approach the tempo run, is to maximize the above two things by balancing two indicators: That the pace is high enough to challenge the aerobic system's limit; and the pace is still easy enough to sustain almost completely aerobically. If too slow my body doesn't get the point that it needs to become more powerful but if too fast, it'll just get more powerful via anaerobic metabolism and pH buffering.

Layman's terms,

The first and lowest metabolic rate is Lipolysis. If there's a ton of oxygen in the muscle cell, fatty acid is metabolism. This is probably the main source at < 65% max heart rate.

The next is Aerobic Glycolysis. If more energy is needed, glycogen is metabolized with oxygen. This is probably 70-80% of max hr. Interesting to note, this requires less oxygen per produced ATP than lipolysis.

The next is Anaerobic Glycolysis. If more energy is needed than the sum of lipolysis and aerobic glycolysis can contribute, the glycogen is metabolized without oxygen. This usually ramps up around 85% of max hr and continues to skyrocket until pH is too acidic, glycogen is exhausted, or muscles are damaged too much, but the true limit is the aggregate of all of those stressors acting on the brain.

The most powerful source of energy is the Creatine Phosphate system. It doesn't really rely on glycogen at all. It's used for the fight or flight maximum efforts for less than about 10 seconds.

Fantastic! This definitely helps!

Thank you,

Layman

Oedipus Rexing wrote:

So you say that lactic acid/lactate does not cause the burning sensation, rather the free H+ ions do so. Basic chemistry tells me that lactic acid IS lactate with an extra H+ ion.

But that doesn't mean every solution containing H+ ions and lactate anions is lactic acid. The reactions are not well enough understood to associate the two as if they were both part of the same product. Without associating the new H+ ions to particular anions, you can't be that specific when calling them an acid. There's bicarbonate around too - maybe they're carbonic acid. Exhaling CO2 does indeed raise blood pH.

Better to just say "acid" and leave the word "lactic" out of it.

Bad Wigins wrote:

Oedipus Rexing wrote:

So you say that lactic acid/lactate does not cause the burning sensation, rather the free H+ ions do so. Basic chemistry tells me that lactic acid IS lactate with an extra H+ ion.

But that doesn't mean every solution containing H+ ions and lactate anions is lactic acid. The reactions are not well enough understood to associate the two as if they were both part of the same product. Without associating the new H+ ions to particular anions, you can't be that specific when calling them an acid. There's bicarbonate around too - maybe they're carbonic acid. Exhaling CO2 does indeed raise blood pH.

Better to just say "acid" and leave the word "lactic" out of it.

Well said. It really is incorrect to say "lactic acid" because those hydrogen ions don't even come from the dissociation of lactic acid. If you read the paper that Northern Star linked to (great paper, by the way), you'll see that the lactate dehydrogenase reaction, which reduces pyruvate to lactate when oxygen availability is low, actually CONSUMES hydrogen ions - it doesn't produce them. The hydrogen ion accumulation is coming almost solely from ATP breakdown (the reaction liberates a hydrogen). And because we breakdown ATP really fast when we exercise intensely, it's only during intense exercise when we really notice the discomfort (because so many H+'s are produced).

So during hard exercise, you have lactate, and you have hydrogens, but they did not come from lactic acid. Something that pretty much every physiology textbook still gets wrong.

Aerobic glycolysis and anaerobic glycolysis are simultaneous, it's never either/or but always both together, but in different proportions depending on pace.

The paper that Northern Star linked partly states:

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

I have also read Canova posts where he mentions that he want his athletes to produce lactate. I'm assuming because it is a fuel source and because it offsets acidosis in the muscles to a certain extent.

So my question is at what paces is optimum lactate produced while minimizing the harmful effects of acid buildup?

Yes, but what causes acidosis on some runs and not others, even when the pace is faster?

I have an answer for you biochemistry buffs to consider. I believe that acidosis is caused by a slightly elevated blood glucose level which can exponentially cause acidosis, whereas a slightly lower blood glucose level will allow more buffering by glcyogen to lactate allowing more non mitochondrial ATP turnover with less H+ production. Perhaps it depend on how much glocose is going to the brain and how much to the muscles?

El Jefe wrote:

The paper that Northern Star linked partly states:

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

I have also read Canova posts where he mentions that he want his athletes to produce lactate. I'm assuming because it is a fuel source and because it offsets acidosis in the muscles to a certain extent.

So my question is at what paces is optimum lactate produced while minimizing the harmful effects of acid buildup?

You can do any race at a faster pace without excess acidosis. Acidosis isn't harmful, that's an old wives tale. The problem is that you are slowing down anyway, it's not the acidosis that causes this.

Have you noticed how, when the adrenalin is really flowing, you can do amazing performances without acidosis or breathing dificulties?

Old wives tale? What the heck are you talking about? According to who?

You can do "amazing" things only when huge amounts of epinephrine are secreted. It is a major catabolic hormone. it drives breakdown of glycogen and triglycerides to produce ATP. After about 10 seconds of this massive ATP production and breakdown, you'll start to feel it. Besides, you have epinephrine released all throughout an exercise bout. In fact, the longer you go, the more epi is released. So that "amazing" feeling can't last forever.

Excuse me, what the heck are YOU talking about?

Read my post again Rod, you seem to have misread completely.

Adrenalin /epinephrine secretion can also last for hours anyway, as far as any race.