Yesterday, I did a 15' muscle tension interval, 55 cadence in my 53X11, 103% FTP, zone 3 HR in the 5 zone system, 2 in the 3 zone system. The interval was not hard at all, though my legs were starting to tire a bit toward the end and they are nicely, slightly sore today, good. I could have gone harder, but didn't want to go out of zone 3. Just goes to show how bad power is at measuring physiological strain.
I don't usually do those intervals at that high a power, but I read that Basso did them at 45 cadence and ~380 watts, probably near his FTP, so I thought I'd see what that was like. It was good. back in the LA days, Basso was my wife's favorite rider. Good man to copy!
I couldn't match Basso's 45 cadence - I was out of gears and on my resistance rollers.