Challenging session today for me, the longest sessions I have done at this intensity have previously been 2x20 mins (10 mins recovery in the middle) and I've not done that very often! I managed to do 40 minutes tonight in the 75-85% zone and kept in in the 80-85% zone for the most part once my HR was up. I guess going from 2x20 to 1x40 is a step up?
For the first 30 minutes my power output was held at 250W, my HR was then slowly creeping up to 85% so for the last 10 minutes I dropped it back to 240W. I warmed up the turbo for 10 mins, calibrated it, and then continued my warmup until the 15 minute mark and then started my effort.
Hopefully be able to increase the length above the 40 mins over time, I suspect I still had a bit of fatigue left in my legs after the weekend's jaunts in the hills of Northumberland.