Thomas Wyss from Magglingen writes: „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.“ https://link.springer.com/article/10.1007/s00421-019-04142-5 For all other physiologists which are NOT interested in intense activities with strong body movements, 3 channel ECG devices are …