If the user knows what he’s doing, rMSSD * HR / 600 is no problem. But if he takes resting HR, from ‘somewhere’ nothing to do with the rMSSD measurement, this will only show BS.
To be meaningful, the HRrest during the HRV measurement must be used. For those using overnight HRV, I would strongly discourage using this.
I can’t be 100% sure but i would think that the same can apply to SDNN.
I already implemented my own preferred way to calculate and implement this. Since I use an external tool to daily get the info from the API and send back some calculated stuff in Custom Wellness fields, I just added the normalized HRV to it.
I use HRV and mean RR from Kubios app and take the natural log from the division.
Differences are subtle, but they do exist!
