have had 2 main breakthroughs this year on Xert. 1 at a crit where i did 250NP for 40mins, and got a predicted threshold of 245, and one this week where i did 270w for 10 mins and got a predicted 244FTP, with some decay in between. Using Intervals ICU & strava estimates, i think this Xert FTP is probably within 5 or so watts of my FTP.
I am starting a polarised build featuring 3 hour Z2 rides. After my 3rd one of these rides this week, which actually felt easier than the previous 2 (including the first one that the break through happened my FTP is down by 4 and Low Threshold power is down by 2. Not making much sense to me as the break through was this week, and these sessions are starting to feel easier already.