March 29, 2008
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I received this email last week…

Hi Carol,

I came across your web site while Googling for information about the
relationship between heart rate and calories burned. On your calculator
page, you express interest in data from folks whose heart rate monitor
displays calories burned, so I thought that I’d respond.

I use a Polar CS200 bicycle computer, and my numbers for the past few
weeks of indoor roller sessions are below. For each session, I give the
date, my average heart rate, my computer’s kilocalorie reading, and the
corresponding result from your calculator. The data is sorted by heart
rate in ascending order, principally to show that for two different
sessions with the same average heart rate, the Polar computer can give
different results. I assume that this is due to the computer calculating
the calorie count continuously over the course of the session, rather than
just emitting one output on the basis of a single static heart rate value,
as most calculators would do. For instance, somewhere else in my Google
search results, I read that Polar’s calorie counting algorithm doesn’t
even kick in until the heart rate exceeds 100 bpm. Another difference in
the numbers is that your calculator tends to be pretty linear, i.e., 9
kilocalories per each beat per minute increase, while for the Polar, the
deltas for each 1-bpm increase jump around a bit.

As far as common constants are concerned, I’ve told my computer that I’m a
61-year-old male weighing 205 pounds, and all of these sessions were 60
minutes in duration.

Date   Avg HR   Kilocalories   Your Calculator
3/11    119         579             728
3/17    127         658             800
3/04    128         670             809
2/29    131         700             837
2/28    133         715             855
3/18    133         715             855
2/25    134         728             864
2/26    135         738             873
3/10    136         742             882
2/22    136         745             882
2/21    138         767             900
3/07    138         768             900
3/14    138         769             900
3/06    138         770             900
2/19    139         780             909
3/20    141         794             927
3/19    142         807             936

Hope this helps,

Bob G
Sedona, AZ