Blood lactate and thresholds: another look

A couple of months ago I read an article by Dr. Inigo San Milan, a leading exercise scientist and training consultant. In it he explains the in’s and outs of lactate and lactate threshold. As far as layperson article goes, its hits the mark, and far be it from me to rewrite what is already written. I recommend that if you are looking for accurate background on blood lactate and a nice comparison between different ability levels, you start with this article. Here is the synopsis of the article:

  • Lactate is not a dead-end waste product, nor does it cause muscle soreness; it also does not linger for days, as some like to think.
  • Lactate “shuttles” out and possibly inside the muscle, and may be used within the mitochondria to produce ATP. *This last part remains controversial but work does indicate that lactate is highly” active and valuable during exercise.
  • Lactate is believed to function as a pro-hormone, and may be a critical factor in endurance exercise improvement.
    • These data come from George Brooks’ lab using cells in isolation. The data indicate that higher lactate levels yield greater mitochondrial production. While we still lack direct evidence on this, the overwhelming evidence that high-intensity interval training produces greater training results than sub-threshold-threshold intensities, indicates that high lactate levels do play a role.
  • The highest performing athletes exhibit relatively low lactate levels even at power outputs of 4.5 W/kg; for a 65 kg rider that’s about 300 W, nearly 70 W higher than a top amateur. These lower lactate levels relate more to GREATER CLEARANCE not lower production.
  •  Most coaches fail to test lactate, mistakingly replacing it with just power testing. While sometimes this is necessary, one must not be fooled into thinking that it is an optimal substitution. Ultimately, too many coaches are using terminology they simply do not understand, and making a mess of it at that! IMO, its an effort to show that the role of the physiologist is unnecessary.
  • Different sports events demand different “thresholds”. I think this is where San Milan starts to get overly complicated.

Here’s the excerpt:

“…we tend to describe lactate threshold efforts to those high exercise intensities we can sustain for relatively short periods of times without “blowing up” and this is where there is a lot of confusion. Where do we define that exercise intensity and period of time at the one we can sustain a high effort?. Is it 5, 10, 30 or 300 min? Is it at 3, 4 or 6 mmol/L of blood lactate concentration? Climbing a 5km Cat-1 climb during 25 minutes without getting dropped requires a specific “lactate threshold”/maximal steady state which could represent a blood lactate concentration of 4-6mmol/L and a specific individual power output (or fractional threshold power/FTP). This intensity however is different than climbing a 10km Cat-2 climb without getting dropped, which may take 40 minutes and therefore a different threshold/maximal steady state which could represent a blood lactate concentration of 3-5 mmol/L and a different FTP which at the same time is different than that threshold or maximal steady state of a 40km TT. Running a marathon at goal pace requires a very important effort at maintaining a maximal steady state which is actually a truly lactate threshold for the entire marathon which elicits a blood lactate concentration of ~2-2.5 mmol/L. This threshold is different and elicits a higher blood lactate concentration for a ½ marathon, a 10K or a 5K race. It seems that each endurance sport has different “lactate thresholds” which are key in order to perform successfully.”

This viewpoint is interesting, and in many ways technically correct, but my question is, what does it really add? Further, will it lead to greater testing? Unlikely. San Milan suggests that different maximal metabolic steady states (MMSS) are needed for different sports, but this does not actually yield anything new, really. Perhaps I’m missing something that Inigo is suggesting here, but assigning a different MMSS to different FTP’s sounds like a new way of describing a zone or intensity. Simply dumping more ingredients into your chile does not make it taste better. He then goes on to make a case for more Zone 2 training, which seems counter-productive for most semi-pro’s; I covered this topic in an earlier post.

My view on lactate testing and training

I’ve recently been rereading one of the best training books written to date, the Science of Winning, by Dr. Jan Olbrecht. If you are looking for a simplified approach to testing, this book has it! While I like Inigo’s test strategy, in my experience, few athletes will take the time or pay the money to undergo the testing Dr. San Milan is suggesting. For world class athletes, his test method is probably an excellent tool to gain insight into a riders total ability, but frequent lactate testing is very valuable, as well, and need only use a couple or three workloads and blood samples. This simplifies the testing and reduces the time and cost, which increases the possibility to test more often. Below is a sample test.

Simplified lactate testing

Here we find the power at 4 mM (often termed OBLA). Improvement in training will push this point to the right, and we could look at HR at this point too. However, nothing is used for training zones, but we can make some assertions based on power, or pace (for running) data and adjust training accordingly. In this way, lactate testing becomes a predictor, a benchmark and a frequent assessment, but not a training zone manager, which is not needed.

Where does HIT fit?

Regardless of the testing and curve we use, HIT will actually impact more potential areas of fitness than any other training. As I’ve already discussed HIT a few times (search HIT), I do not want to be labor the area. However, suffice it say, HIT will shift the line/curve to the right, as well as increase the ceiling (i.e., max). It also improves lactate clearance and mitochondrial production (to “eat up” all that lactate), and improves fatigue resistance in both the Type I and Type II muscle fibers. In other words, endurance and power improve. Again, this is not say that HIT is the end all and be all of training. As shown in our polarized training article, for the high volume athlete, an 80/20 split seems ideal, while for low volume folks, a HIT focused program may be best.

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