# Maths HRM question - only read if you like figures!

Posts: 1,372 Member
Some members on here have said this and I was wondering if it's true as it has quite a big impact on calories consumed.

When you exercise, your HRM will give you a reading for the work you have done - let's say 700 calories for an hour cycling.

To get the true figure you need to take off the calories you would burn if you were doing nothing at all - your BMR, as that has already been accounted for so...

For me with a BMR of 1539, I burn 2.67 calories per minute just keeping alive, so any exercise I do is NOT in addition to that.

60 minutes no exercise = 160 calories
60 minutes of exercise (HRM reading) = 700 calories

So the EXTRA calories I burnt off were 540 calories

In practice then I burn 1539 a day if I did nothing at all (My BMR)
I factor in my TDEE based on NO EXERCISE (BMR x 1.2) to get calories burnt including moving about, walking upstairs, making dinner etc.
TDEE = 1847

I then do some exercise (HRM reads 700 calories so I take off my BMR figure to get 540 calories)

So in theory I burnt off:
TDEE = 1847
Exercise = 540
Total = 2387 calories

If I consumed 2387 calories then in theory I would stay the same weight

I understand all figures are always very much estimates, but I'm interested to see if the maths is correct

## Replies

• Posts: 3,497 Member
Bump - keen to see responses.
• Posts: 84 Member
Bump
• Posts: 507 Member

I understand all figures are always very much estimates, but I'm interested to see if the maths is correct
For you with a BMR of 1539, you’d burn 1.06875 calories per minute, half what your figures are based on.
So your 60 minutes without exercise (just to live) 64.125
So your 60 minutes of exercise 700 - 64.125 = 635.875
• Posts: 1,372 Member

I understand all figures are always very much estimates, but I'm interested to see if the maths is correct
For you with a BMR of 1539, you’d burn 1.06875 calories per minute, half what your figures are based on.
So your 60 minutes without exercise (just to live) 64.125
So your 60 minutes of exercise 700 - 64.125 = 635.875

Yes you're dead right - I used a pre-programmed Excel calculation - clearly wrong, thanks

But is the theory correct? Do I need to take my BMR figures from the HRM results?