Originally Posted by Creatre

I'm assuming he means he's doing upper z2 or lower z3 work. 90min of this can be "fatiguing." He is noticing less "fatigue" when getting to the last section of the ride. May be more of an endurance thing, but still, in theory it would be increasing the right side of his curve like he said. He should be able to make more power at the before rpe for the time duration.