It does have some basis in fact- I can produce 250 watts at a cadence of 70 rpm, and a heart rate of 165.
If I change gear and spin at 90 rpm my heart rate drops by 10-15 bpm.
So I am producing the same power but exerting less energy to do so, which means I can do it for longer before falling over sideways and starting to dribble.
It does have some basis in fact- I can produce 250 watts at a cadence of 70 rpm, and a heart rate of 165.
If I change gear and spin at 90 rpm my heart rate drops by 10-15 bpm.
So I am producing the same power but exerting less energy to do so, which means I can do it for longer before falling over sideways and starting to dribble.