Jono, I suspect that it is LT2, but these terms are not always universal. “LT2” could mean one thing to one coach/lab and something else to another. Any chance you could share the test results with me? email@example.com. I bet if I take a look I can confirm. The delta between LT2 and MaxHR makes me think your LTHR could be a bit higher than 166.
Thanks for sending over your lab test. First, I am not an expert in lab testing. I don’t want to position myself as being able to interpret your results better than the technician who performed your test.
With that, I have two observations:
– Your lactate mmol per liter was 4.2 at 171. 4.0 is considered LT, which would imply your LTHR would be closer to 171 than 166. I would check in with the lab on their interpretation of this. Regardless, the LT2 the lab specifies is really close that lactate accumulation.
– This is the problem with all lab testing: it is inside. Inside HR will always be lower than outside, by about 5 beats. The reason the field tests we recommend are likely to be more accurate than your lab test is that your field test will be done outside, where most of your training is.
So, for indoor training, your lab test is a better LT (I’d still argue slightly higher than 166 based on lactate mmol per liter). For outside, our field tests are better where I estimate you’ll be close to 174.