The Apple watch 9? The Polar H10? A 3 channel PiEEG ECG device with HeartPy? HeartPy – the Python Heart Rate Analysis Toolkit https://python-heart-rate-analysis-toolkit.readthedocs.io/en/latest/ For runs faster than 15 km/h and if if intense activities with strong body movements are investigated, we suppose that the Polar H10 chest strap is the most accurate devices, as …