Discussion: Altitude / Power

A couple of years ago I rode over some Alpine passes at 2400m
Power meter told the tale.
At that altitude I was producing only 60% power for heart rate compared to normal

I don't think I felt great low down the hill either, so not sure how much I can put down to altitude. Maybe a combination of altitude and heat, but I'm also sure that I'm not as fit as earlier in the year - so that's the first thing to look at

Cumulative fatigue? You've had a tough run of races and training