Lactate Test #1: Where am I starting from?

May 17, 2018  ●  3-minute read

On April 7th, I did my first lactate capacity test of the training season. A lactate capacity test tells you:

  • Your aerobic capacity by plotting ~2 mM/L and ~4 mM/L against pace and heart rate;
  • Your anaerobic capacity by measuring the peak lactate output during the test; and
  • The relative strength of each system: aerobic versus anaerobic.

The first test of the season gives me a baseline to work from and an indication of what I need to work on. It’s only an indication because each training season starts off the same: maximizing both aerobic and anaerobic capacity.

Later, anaerobic capacity can be shaped to be more race-specific. Aerobic capacity doesn’t need to be shaped, because the desired outcome is always the same: the more aerobic capacity, the better.

Here are my April 7th results:

A graph of the first lactate capacity test
My first lactate capacity test of the season: Aerobic capacity (AeC) is less than it used to be as is shown by the red line being higher and more to the left than the blue line. Anaerobic capacity (AnC) is higher than in the past as is shown by the peak lactate output achieved during the test (14.6 mM versus 8.1 mM). (Ignore the speed associated with AnC. I plotted it where it is so that the graph wouldn’t be too wide.)

Aerobic & Anaerobic Capacity

Compared to the last time a did a capacity test, my aerobic capacity has declined (in both heart rate and m/hr) and my anaerobic capacity has increased (in mM/L). Unfortunately, my previous test was so long ago that it’s hard to draw any conclusions about what has created the difference between the two tests.

There are a couple of safe assumptions though.

A decline in aerobic capacity is to be expected at the end of a race season. A high volume of high intensity will always reduce aerobic capacity. Intensity increases the acidity of blood in the muscles, and over extended periods of time, chronic levels of acidosis kill off mitochondria, the “aerobic engines” of our cells. As mitochondrial mass is reduced, so is aerobic capacity.

The increase in anaerobic capacity is likely due to two factors: 1) the fact that I’ve been specifically training it since the summer of 2016; and 2) as aerobic capacity decreases, anaerobic capacity may appear to increase.1

What should I do now?

When I first saw my most recent lactate curve, it told me what I needed to know. I needed to make my aerobic capacity relatively stronger while maintaining or also increasing my anaerobic capacity. If that could happen, the lower part of the curve would shift down and right, and the peak lactate value would exceed 14.6.

The first order of business is to increase aerobic capacity. You can’t build a house without a foundation, and aerobic capacity is the bedrock for everything that comes after. (In absolute terms, I suspect that my aerobic capacity is stronger than it was in February 2016, but more on that later.)

Ideally, I’d be able to increase anaerobic capacity as well. It’s been higher in the past, and having it high early in a training season is an advantage. Some think that a higher anaerobic capacity allows for a higher training volume. More observable is that the higher I can make AnC while training, the powerful it can become closer to race season.

My next lactate capacity test is in a few days. I’ll post the results once they’re complete, along with a summary of the training I’ve done in between the two tests, and the rationale for the types of training that I’ve used.


    • A lactate curve doesn’t actually show absolute values for aerobic and anaerobic capacities. It shows the relative balance of the two. So if one gets relatively stronger or weaker, while the other one stays the same, the one staying the same will appear to get weaker or stronger, respectively.

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