AeT Test Results and Questions

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  • #33841

    This is my first post here, although I’ve followed along for a while now and have been implementing the ideas in TftUA since I bought the book a few months back.

    I am a 37-year-old male, fairly new to longer-distance running. I recently ran a half marathon that I had been training for. My training was for about 5 months, primarily with runs at or below AeT, which I determined based on a combination of the Maffetone method and the nose breathing method. I basically tried to keep my AeT runs around 145 bpm for heart rate, or below. Towards the end of my training, I implemented a few threshold-type runs.

    I just had a lab test done to determine my AeT and got some interesting results I wanted to get some input on. My resting blood lactate before the test started was 0.9. I warmed up for 15 minutes with a brisk walk, my lactate dropped to 0.8, then went up to around 1.3 at the end of the warm-up when my heart rate was around 110.

    We started the test and got the following numbers:

    HR Blood Lactate
    140 1.5
    146 1.5
    148 1.9
    153 1.3
    157 1.5
    160 2.4

    I am just wondering if anyone has seen blood lactate drop like this (from 1.9 to 1.3) or whether this was some kind of error. I was thinking error, but then the next measurement was 1.5 so it seems unlikely that there were two errors in a row, although that is possible.

    Can I get some feedback on what everyone thinks about this? I am thinking my AeT is in the low 150’s based off of the test, but am not sure.


  • Inactive
    Anonymous on #33897

    The rise-then-drop is normal and common. Your aerobic system was still warming up. Then once it was, it reduced the lactate in your bloodstream. The aerobic system uses three fuels: oxygen, fat, and lactate (pyruvate).

    I think you’re safe to use 155 as your AeT HR (the upper limit of Z2).

    Did the test go any higher? Did it record HR at ~4 mM or MLSS?

    ccl127 on #33907

    I appreciate the response, thanks! Test did not go to 4, we stopped at 2.4. I’ll probably go to 4 to the next time I have it done.

    If I was still warming up with my heart rate that high, I guess my actual warm up was not intense enough?

    Anonymous on #34080

    It depends. It’s better to underestimate a warm-up than overestimate, especially for a lactate test.

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