Is it possible to calculate the number of calories burned by using your average heart rate and elapsed time?

You can get a ballpark figure (way ballpark really). To be somewhat accurate you have to know what your max HR is and it's very helpful to know what your anaerobic threshold is. Without knowing these numbers you are really just guessing, which is only slightly better than using those silly scales you can find online that say things like:

walking 200 cals/hr
mowing the lawn 300 cals/hr
basketball 500 cals/hr
sex 1,000 cals/hr etc, etc,

these scales are wildly off, in general because when doing something like playing bball you can be playing lazily and diving after loose balls and running around like AI, which would be a difference of about 800 cals/hr for the same activity.

If you use the 220-age (m) or 226-age (f) scale for est max HR, which is always wrong, and you know your resting HR, you can vaguely figure out training zones which can give you an idea, which is probably with 200-300 calories. This isn't too accurate given that an easy workout might only burn that much.

I like to always underestimate so here's a scale to use:

1,000 cals an hour = you totally killing yourself for an hour. Drenched in sweat, heart feeling like it's about to explode, like racing a bike.

800 in a hour is a very hard continuos workout. Pumped for most of it.

600 an hour is a hard workout like BIU or two PHH's.

400 an hour would be if you did BIU and were really lazy and didn't use very much weight. You were sweating but never very tired and never pushing to failure.

300 an hour would be an easy but continuous hike

200 an hour would be stretching while watching tv and getting up at every commercial to walk to the fridge and eat something.

Can you give some underestimates of cals burned for P90 workouts, much like you did for Slim in 6 workouts? Thanks!

Thanks FA. (I caught the AI reference )

Can you provide estimates for each of the P90 tapes for both male and female?

In light of your response, is there any value in a heart rate monitor during P90?

I think these estimates in somewhere in the FAQs right now but I'll do em again. I think we gauge off of this type of scale for our workouts but keep in mind if you're never pushing til failure you're not getting full benefit from the workout:

P90X = 600
BIU = 600
RIU = 400
P90 3/4 = 400
P90 1/2 = 300
PHH = 350

Here's a HR monitor article that is a must read, if I do say so myself:

http://www.beachbody.com/jump.jsp?itemID=58&itemType=NEWSLETTER_ISSUES