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.

Thanks!