Lactate Testing - Data and Results

thx, I am new here.


Part of my interest in LT1 is for metabolic health. As an overweight FORMER cat 1 cyclist with a family history of type 2 and evidence of some insulin resistance in my 40 year old body, I want to make sure that I make the metabolic changes needed to increase mitochondria as I come off the couch. I care about pushing LT1 up in order to encourage my body to prefer fat as fuel for regular rested living because I think it might curb over eating derived from blood sugar peaks and valleys resulting from insulin resistance. I also want to do the ISM training and get the work at FAT MAX done and get faster at low HR. But that is secondary.

Does anyone with the metabolic goal have input to that end? Also trying to maximize volume because I happen to have time for the next 6 months and want to drop weight and build base for further training in years to come. Any input on that would be appreciated. I have 10-15hrs a week, but only for the next 6 months, and then back to 8-10.

The problem with a NIRS device is that it really doesnt tell you anything, until it tells you everything…
The daily variations in SmO2 is quite big, for me cycling it ranges from 85% to 75%. Does it give me realtime feedback of lactate? Yes, but no. You have to look at the sloperate to have some understanding of it. That means you have to use many parts of your brain while biking :stuck_out_tongue:
But after using my Moxy for 4 months, combined with a lactate meter I have a good understanding of what rates gives what values, and at what intensities I would expect to see the different SmO2 values depending on day to day variation.

This is a link to protocols for lactate testing. There are also some articles on the site as well. Blood lactate testing protocols for cycling — High North Performance

Very similar main goal to me. Family history of heart disease though. I do a lot of riding below LT1, At least I thought I did until I got a lactate meter! I’ve be reduced the intensity of most of my solo rides as a result. Early days so I’ve yet to see any major effect of it. One thing though I know it’s not doing me any harm.

I did a lactate test yesterday, for the first time in about 18 months. I followed the protocol recommended by Alan Couzens in his Substack book—15-min easy warmup, then 5-minute steps of ~25w. For HR I just put a guesstimate of the average HR in the final minute of each step. For the final step, I did hit my HRmax of 183, and was surprised to see I was able to hold 180+ for the final two minutes of that step (I am 57). My BLa was 10mmol after that step, so I called it a day.

My main interests are:

  1. Seeing how BLa aligns with my RPE of LT1. I have been trying to keep my training really polarized, doing a lot of very easy endurance, so that I can add more volume. These days, I am doing a lot in the 190-205w range, which looks like less than 1mmol.
  2. Comparing these results to the two lactate tests I did near the start of training—off the couch in Dec 2021, and three months later in March 2022. These two tests were administered by others with different protocols (3-min instead of 5-min steps), so if anything, they were overstating my abilities back then.
    The three lactate traces are yellow for Dec 2021 (a true max effort, I still remember!… based on the ramp test I did, I would guess my VO2max was in the low to mid-30’s), green for March 2022 (they only tested to the first 1mmol rise in BLa, but I also did a metabolic cart VO2max test at the same time, with 47.1ml result), and light blue for yesterday.
    NB. The HR data is for yesterday only.
    Sorry if the chart is not formatted well—this is my first time to make a spreadsheet chart. Any feedback appreciated.
    ETA: Dec 23 is a typo. Read “Dec 21”


Tnx for sharing your data and congrats on improvements.



What would you mark as your LT1 zone? Around 210w?

So, my general idea with the test presented above was to just get an overall picture of my lactate profile. But I also wanted to get a better look at LT1, since the area below that is my primary training zone. HighNorth suggest doing a second test with 10min steps of just 10w for getting a better view of LT2, so I decided to apply this idea for drilling down on LT1.

So the day after the general LT test presented above (i.e., yesterday), I did a 10min warmup at 126w, then 5min at 158w, then starting at 186w, I did 10min steps, just bumping the wattage by ~10w each step. Aside from what seems like an aberrant reading at 195w, the BLa values stayed well under 1mmol all the way through 224w, so this entire range seems like it’s definitely below LT1. The next step, to 236w (a slightly larger 12w bump to keep the average at 10w), saw a rise to 1mmol, and from there it has a steady rise to 2.2mmol at the final 265w step.

Based on this, I would put LT1 for training purposes conservatively at 224w, where I had readings of 0.7mmol and 0.6mmol. In his Substack book, Couzens explains this interpretation of LT1 (AeT):

To account for the typical error in portable lactate testers, the magnitude of the initial rise is generally taken as somewhere between 0.3-0.5mmol/L. I recommend using the point before the first rise of >0.3mmol/L when defining the Aerobic Threshold. This was the number that the Sports Science team used at the A.I.S. and it works well for most monitors.

NB. The blue dots are the BLa readings from this test (10min steps, 10w increments). The green triangles are from the VO2max lab test I had done 18 months earlier, with 3min steps (VO2max tested at 47.1 for reference). The red triangles are HR.

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