T Nation

Daily Calorie Usage

Guys this morning I used my new heart rate monitor. after working out it said I burned 1000 calories. Great, well I was a little curious to see how many calories I will burn today, so I am still wearing the strap and it says so far for today I have burned 7990 calories. I don’t know but that seems a lot.
I got home went on a website that calculated your daily calorie usage, you know punch some numbers in a viola i should burn 3869 today.
Can someone help me with this ? the heart rate monitor is calibrated to my weight.

A heart rate monitor cannot determine calories burned. It will probably overrate numbers for people that are out of shape. If you are out of shape you probably have a higher heart rate, so the monitor will think you are constantly working out while you are not.

If you are in shape the monitor will probably underestimate calories burned, because you will have a lower heart rate.

For example, let’s say one person is in really good shape and has a resting pulse of 50 bpm. He decides to walk up 20 flights of stairs and his heart rate increases to 100 bpm. Now let’s assume another guy is out of shape with a resting pulse of 100 bpm. While he is sitting on the couch the computer in the monitor will say he is burning as many calories as the guy walking up the stairs.

The monitor is also using weight, but that is an inaccurate gauge of calories burned. A 200 pound guy with 5% bodyfat burns a lot more calories than a 200 pound guy with 25% bodyfat.

Also the heart has 2 ways to increase the amount of blood pumped. One way is to increase the amount of blood pumped with each beat. This is known as stroke volume. The other way is to increase the heart rate. The monitor is only reading one of those, so is not even an accurate gauge of cardiac output.

In short, there is no way your heart rate monitor can accurately predict calories burned. It is using only one variable, but to be accurate would have to include countless other variables.

BigdaddyT has the right idea. The webiste you’re looking at is much closer. The monitor is great for heartrate, but no way it can calculate calories.

I figure as much, it was really high…