So, I have done the test tonight (or rather just wanted to see how it works). First of all, I forgot to calibrate my power meter, so any numbers were not accurate for sure (I changed my chainring, it was a way warmer than yesterday etc.). Too bad I recalled about it in the last 10 mins or something. I believe I used too big gear too, as I was riding about 86-89rpm for the test and the problem was with my legs here definitely. Maybe I was a bit overtrained after yesterday. The most weird thing was with my HR as the maximum for the whole activity (warmup + 20 mins) I got only 158bpm and my average for the 20 mins was 142bpm. This is a way too low. I actually feel like my heart rhythm could go upper, however I couldn't maintain a higher cadence as I felt my legs empty. So, I believe I was overtrained and not recovered yet and/or I used too big gear for the test.