A paper of the Swiss Federal institute of Magglingen says: https://pubmed.ncbi.nlm.nih.gov/31004219/ «A simple chest strap such as the Polar H10 might be recommended as the gold standard for RR interval assessments if intense activities with strong body movements are investigated». 1. The iWorx TA 220 with the iWorx ECG toolbox 2. HeartPy with for instance …