If you like needles, here a good listing of methods for determine LT1/2,
https://upsidestrength.com/blog/lact...nterpretation/ or you can fumble with heart rate, 65-80% of max (
https://en.wikipedia.org/wiki/Lactat...bic_thresholds). Personally, I go by top of Coggan zone 2 and lower bound of zone 4 and call it a day.