Rob ter Horst claims in the following video that the Polar H10 «is the gold standard in science» for heart rate measurements: The information is from this paper: RR interval signal quality of a heart rate monitor and an ECG Holter at rest and during exercise: https://scholar.google.com/scholar?hl=de&as_sdt=0%2C5&q=RR+interval+signal+quality+of+a+heart+rate+monitor+and+an+ECG+Holter+at+rest+and+during+exercise&btnG= The paper was published in 19 April 2019 …