I am extremely confused right now...
So today was the first day I wore my Polar FT40 to a Zumba class. It said I burned 922 kcal during 60 minutes. BUT before, when I used my FT4(which is supposed to be less correct than the FT40) it said I burned around 560 - 600 kcal/class... And I don't know which HRM I should trust. Anyone else having this problem? Or a…
