Originally Posted by Drew Eckhardt

There's a power-dependent cadence producing minimum muscle activation which increases with power. This seems to impact fatigue and time to exhaustion.



Right.

From Cadence, power, and muscle activation in cycle ergometry







Reduced inertial load as from climbing or a trainer may preclude getting there due to the muscles getting you through the dead spots at 12 o'clock and 6 o'clock. Hence the example in _Training and Racing with a Power Meter_ of the racer who got dropped every time he spent more than five minutes at his FTP but cadence below 70.