The official cost of the test was 280 CHF (about 300 USD), though it was done by a friend and I think that he was able to write it off as development testing while he was setting up a new lab. Still, for me it would have been a price worth paying.

It was a maximal stress test on an SRM ergometer, with measurement of lactate, VO2, respiratory quotient (RQ), with discussion, analysis and report by the exercise physiologist after.

I don't have the expertise to comment on the value of home blood lactate testing. From talking to a couple of exercise phys I know, one of who works at world tour level, I'm thinking it depends on what philosophy you buy into. For instance, Iñigo san Millán is a big proponent, but not everyone agrees with him... In my case, my LT1 and VT1 were measured to be 250 W. My LT2 was at 323 W. None of these values were much surprise to me, indeed the LT2 was just a few Watts different to my self-assessed FTP. However, the RQ showed that at just 200 W I was already burning 80% sugars. This information was a) useful and b) actionable. Further, since it was not correlated with LT1, it would not have been shown by lactate testing alone.

I'm curious how you would action the 200w / 80% sugars piece of information. In long course triathlon, aren't we (almost) always trying to maximize the % of fat oxidation at most race paces?

Once you know that rate, how do you go about changing it - other than through generalized training principles? (Mostly Z2 work, limit your dietary sugars, the odd fasted workout might help, etc)

Was your LT1 (250 W) approx 75% of your MHR?

I downloaded the HRV logger app and just did an ez endurance ride trying to nail in my level. Everything worked pretty well, results were completely unsurprising (using Garmin HRM dual).

One question I have is it seems a lot of folks here naturally want to push up against this barrier in their endurance ride. Is there any research or other reason to believe that doing your rides nudged up against lt1 results in better outcomes than giving it a wider birth and just staying below?