Here is (perhaps) a “back to basics” question. Mostly for fun.
Is there a way to calculate what would be the Variability Index (VI) of heart rate over a given duration, similar to what is done with power? Is there even a need? I think the need would be generally the same as power variability index. Perhaps the “zero value” would be the floor value of what is recorded during the session.
Caution: I’m not talking about Heart Rate Variability (HRV), which is a separate, well-defined, and generally accepted metric.
Perhaps this is a well-known measurement under a different name?