When doing a workout, there is (at the bottom of the screen) a Watts over time graph. All Zwift developments needs to do is to enlarge this, with Watts and time metrics on the Y and X axis and have it where one can download it. I will be super-surprised if 90% of Zwifters are not desperately wanting that. Super-imposing that curve on heart rate (which might be from another source) will then be indicative of the extent that “uncoupling” is taking place.
Can anybody think of a better way to measure aerobic fitness??!!