heart rate monitors and interval training....

lafournier2

I just bought a heart rate monitor, I'm new to the whole thing, and I was wondering if anyone could give me some pointers on how to best use it while I'm doing Insanity. The whole point of insanity is to get your heart rate up for 4-5 minutes at a time and then have a 30 second period to let it drop before getting it back up again. When would be the best times to push the heart rate button to be the most accurate reading on burned cals? Should i push it during the peak of the intervals and then when i rest as well? Any help is greatly appreciated!