HRM vs. Logic

WKenL

I bike quite a bit, and use the heart rate monitor for tracking purposes.

I'm puzzled by some of my results, and wonder if anyone has thoughts.

When riding to work (about 5 miles away) it's almost all uphill, it's hard riding for me at this point (though I no longer have to walk even the worst hills), and takes about 50 minutes. According to the HRM, I burn about 350-400 calories on that ride.

My return along the same path is, of course, almost all downhill. A lot of coasting is involved, and sometimes I'm pedaling just to maintain cadence. Even at speed 24 there's almost no engagement for a not-insignificant amount of the ride. In 25 minutes the HRM comes up at about 250-300 calories.

I suppose that my cadence is a faster on the return trip, trying to keep some kind of resistance going, but does that really explain why my per-minute rate is so much higher on a far-easier ride?

Any thoughts would be greatly appreciated.

wellbert

When you're coasting, your HRM still thinks you are doing cardiovascular work because your heart rate is still higher from when you were pedaling. So basically, the HRM is counting ALL THE TIME - whether you are exercising or not.


It's important to remember that HRMs do not and can not count the calories your body burns during activity. The only thing they do is measure your heart rate and apply a formula to it to calculate an estimated calorie burn.

For example, if you were to hold perfectly still and somehow elevate your heart rate to 140bpm for 20 minutes,
and as a comparison, go for a jog at 130bpm for 20 minutes,
The HRM would record the first one as the highest calorie burn.

patchesgizmo

When you're coasting, your HRM still thinks you are doing cardiovascular work because your heart rate is still higher from when you were pedaling. So basically, the HRM is counting ALL THE TIME - whether you are exercising or not.


It's important to remember that HRMs do not and can not count the calories your body burns during activity. The only thing they do is measure your heart rate and apply a formula to it to calculate an estimated calorie burn.

For example, if you were to hold perfectly still and somehow elevate your heart rate to 140bpm for 20 minutes,
and as a comparison, go for a jog at 130bpm for 20 minutes,
The HRM would record the first one as the highest calorie burn.

So I am thinking then if your heart is kept slow medically with a medication like atenol then the HRM cannot even begin to correctly calculate your calories burned. So then how are you supposed to calculate your calories?

wellbert

When you're coasting, your HRM still thinks you are doing cardiovascular work because your heart rate is still higher from when you were pedaling. So basically, the HRM is counting ALL THE TIME - whether you are exercising or not.


It's important to remember that HRMs do not and can not count the calories your body burns during activity. The only thing they do is measure your heart rate and apply a formula to it to calculate an estimated calorie burn.

For example, if you were to hold perfectly still and somehow elevate your heart rate to 140bpm for 20 minutes,
and as a comparison, go for a jog at 130bpm for 20 minutes,
The HRM would record the first one as the highest calorie burn.

So I am thinking then if your heart is kept slow medically with a medication like atenol then the HRM cannot even begin to correctly calculate your calories burned. So then how are you supposed to calculate your calories?

Yes, medication can have a huge impact. The formula will assume you aren't working as hard if your heart rate is artificially lowered.

WKenL

Thanks, wellbert. That makes a lot of sense.

I think that I might halve the calorie count for the return trip in my thinking, just for the purpose of making sure that I'm making my goals there.