Using Autonomic

A chest strap reads your heartbeat electrically instead of optically, which is the difference between beat timing that is accurate to the millisecond and beat timing that is guessed. That matters enormously for HRV. The Polar H10 is the research-grade default and what we recommend if budget is not the deciding factor. The COOSPO H808S costs a fraction of it and, in our testing, produced readings we could not meaningfully separate from the Polar's. The Polar is a little more comfortable over long wear; the COOSPO beeps audibly when it connects and disconnects, which some people like and some find irritating. Either one will transform your data.