Quick question about definition of "high intensity"

I've read several places that keeping your heart rate at 70-80% of your max is considered high intensity; but it seems most calculators use the "breath test" i.e. - medium intensity = you can talk during work out...and high intensity = you are sucking wind. Which do you use and why? This makes a lot of difference when you figure calories burned in a work out because if you can talk, it's medium intensity even if your heart rate is 70-80%; I just don't get it.

Are you talking about which option to use on the FS exercise options? I use my heart rate monitor to tell me how many calories I've burned, and then I select "other" and enter it manually. Many members have discussed that the exercise options frequently overestimate calorie burn by a long shot, so if you're going to use them, I would 'underestimate' the intensity to get a more realistic calorie burn.