Bike Forums > How do HRMs calculate calories burned?
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 01-10-06, 05:12 PM #1 erhan Newbie Thread Starter     Join Date: Apr 2005 Bikes: Posts: 708 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) How do HRMs calculate calories burned? I was just thinking about how accurate they are, but I'm a little confused. The only input variable is the users heart rate. There are also pre-entered/constant values like age, resting HR, max HR, and weight (not sure how they are used for the calculation). Ok, here is what confuses me. Let's say in reality I am burning 700 calories in one hour, with an average HR of 160 BPM. After some time, I become more powerful, none of the constant values change (age, weight, etc.), and I am burning, say, 1000 calories in one hour, with the same average HR (160). If what I said above is correct, then a HRM has no accurate method of calculating the calories burned. Am I right? Also, does anyone know a mathematical formula for calculating calories burned, based on HR? Thanks
 01-10-06, 05:20 PM #2 socalrider Senior Member     Join Date: Mar 2004 Location: Upland, CA Bikes: Litespeed Liege, Motorola Team Issue Eddy Mercxk, Surly Crosscheck Cyclocross bike, Fisher Supercaliber Mtn. Bike Posts: 5,023 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 3 Post(s) Most HRM ask you to input height / weight and age.. From that and effort during an exercise it gives you calories burned.. I always felt that they estimate a little on the high side..
 01-10-06, 06:57 PM #3 terrymorse Climbing Fool     Join Date: Dec 2004 Location: Palo Alto, CA Bikes: Scott Addict R1, Felt Z1 Posts: 3,019 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) The Polar 700 series HRMs ask you to enter your personal VO2max figure, which scales linearly with power and calorie consumption. More oxygen consumed = more calories consumed. __________________ Managing Director, Undiscovered Country Tours