Here is an example of why I think it’s helpful to know both heart rate and power. Here’s a screenshot of a part of today’s ride, climbing the main hill.
You can see that heart rate rises early in the climb and continues to increase as the climb progresses. You can also see that with each steeper section I’m able to put out a decent amount of power to a certain point. After that point each power peak is smaller and smaller, yet my heart rate stays very high (unusually high). I’m putting in a high level of effort but my legs are unable to continue putting out high levels of power. They’re done in.
This makes sense of course, because I’ve not been doing any aerobic training for the last six weeks that I’ve been in plaster and my legs have “detrained”.
My point is that without the heart rate data I would have been wondering if I truly had been putting in a decent effort. The power data is obviously useful.
By repeating this session I’ll be able to see in the data if my fitness is improving. Good, eh?