No reason in terms of accuracy, but possibly harder to view, and it is unlikely that the backlight gesture settings will work correctly.
In general, the watch should be positioned on the fleshy part of the wrist well away from the wrist bone (larger blood supply for the OHR to measure), and the band should be pretty snug to prevent external light from entering the sensor (I find I have to have the band 1 notch tighter for running than I do for 24/7 monitoring). Some people have success switching to their other wrist (but still face-up).
No reason in terms of accuracy, but possibly harder to view, and it is unlikely that the backlight gesture settings will work correctly.
In general, the watch should be positioned on the fleshy part of the wrist well away from the wrist bone (larger blood supply for the OHR to measure), and the band should be pretty snug to prevent external light from entering the sensor (I find I have to have the band 1 notch tighter for running than I do for 24/7 monitoring). Some people have success switching to their other wrist (but still face-up).
Thanks. I haven't had any problem with the backlight working correctly when I twist my wrist to see (while facing down). In fact, I find it easier to view since I do not have to rotate my elbow.
