The HR always seemed very low. I went for several hikes lately gasping for air at times and the highest HR FitBit Sense registered was 110. I bought a Peloton and a chest HR monitor from them. FitBit HR is always 30-50 points lower!!! So frustrated I wanted to throw the thing today. HR is so important in measuring calories burned. I’ve been wearing FitBits for 13 years and am not happy with this one. For the price of this watch, there should be a recall/exchange program.