Originally Posted by nelie
Much more accurate would be to have a HRM with a chest strap.
And if you're going to go that way make sure it's a comfortable one. For fun I wore mine to school the other day. Long story, but just wanted to see if there was much difference between my daily burn rate at home (gardening, computer, etc.) and being at school all day. I had it on for 10.5 hours and tucked the watch, with the buttons locked, into a pocket. I never wear a watch, and I knew it would drive me nuts on my wrist. I really pretty much forgot I had it on.