Polar F4 HRM showing fewer calories burned than machines

After reading some postings on CC that said that their HRM's showed more calories burned than the machines at the gym I purchased a Polar F4 in order to get a more accurate calorie burn. Its showing fewer calories than the elliptical and bikes I use at the gym. Both machines require weight to be input so their calorie calculation shouldn't be far off. The Polar F4 is showing about 20-30% fewer calories burned.

Which is more accurate?

Dunno, but it doesn't seem like you could tell how many calories were burned just from your heart rate. Like, as people get more fit it takes more work for them to get their heart rates up.

It just depends.  When you set up you HRM did it ask you to input max heart rate or age?  If it asked age than it is calculating your training zones based on 220- age = MHR.  This can be way off and will through off the calorie burn estimates.  If it only asks age and you have an idea of your MHR adjust your age so you get the right training zones.

I think its right. My F6 usually says about 350 calories burned for 35 minute w/o on my elliptical. The elliptical itself says 700 calories. I love my HRm, and wouldnt exercise w/o it.

PPl have their opinions about HRM, but I had a doctor tell me that the only way to get an accurate account of you cals burned is by wearing the strap. The machines are simply wrong. PLus...you can keep your HR in your zone w/o having to hold on to some handles.

I know with my F6 you program it to YOUR own body, so yours is probably the same. AS long as you have it set with all your info there shouldnt be a problem.

On the treadmill my HRM is about 2/3rds of what the treadmill says, on the elliptical my HRM is dead on, or higher then the treadmill. Honeslty not sure which one is the most accurate.

Original Post by trhawley:

It just depends. When you set up you HRM did it ask you to input max heart rate or age? If it asked age than it is calculating your training zones based on 220- age = MHR. This can be way off and will through off the calorie burn estimates. If it only asks age and you have an idea of your MHR adjust your age so you get the right training zones.

It asked for age, height, weight, and heart rate limits. You can overwrite the limits, which I need to do because I am on BP meds which affect heart rate.

It could be that the BP meds are throwing things off I guess.  How do the numbers compare with the charts on this site?

Let me add, the problem I have with HRMs that use age to calculate intensity levels is that I'm 49 and my MHR is 190.  If I input age the monitor will assume that I am working a high level of intensity when my effort is only moderate therefore throwing off the calorie burn estimate.  I compensate by putting in the age (30) that gives me the right training zones.  This gives me a better estimate of calories.  But for me the HRM is not far off from the estimates on this and other site.

I've been thinking about using a higher age to adjust for my meds. Right now tho, I input 105 for the lower limit and 125 for the higher limit. When I had a stress test last week the max I reached after 10+ minutes was 137. At the start they wanted me to reach 161! My Cardiologist said to use 110 as my target. I get there but not for the whole workout.

This site's values for light effort on elliptical seem closer to what the HRM generates while my effort based on being able to talk etc seems more like moderate to vigorous.

I'll play with the age it a bit and maybe it will be more in line with the machines. But the machines only ask for weight and do not factor age in. I'm not sure what age to use to have it generate more correct values. Could be I'll have to say I'm 90! Wishful thinking!

I ran some numbers. Built a spreadsheet using various target heart rate formulas. I then used the max heart rate from my stress test, 137 (which yields a target 60/85% range of 82-116. Which would be an age of 81 using the old standard of 220-age type formula, which is what I think the Polar F4 must use since there is no input for fitness, although it could be using the Karvonen formula, which would mean and even higher age of 105 using Karvonen, and 95 using 214-.8*age formula for max HR!

I'll try both if it allows me to go that high in age... and will post results here.

Well, I can't get the Polar F4 to agree with the machines, even when I enter an age of 99 into the machines they show a calorie burn 30-50% higher than the F4 does.

I reset the age in the F4 to 61 and it reset the limits using the 220-age formula. So I know what it is using I think I'm going to reset the age to 81 so that the max heart rate matches what the stress test yielded, 137. I don't know if that will increase the calorie burn, but it should be as accurate as I can get from the F4. It looks like the machines are always going to run high.

Keep us informed. Thanks.

If I were you I would just totally ignore the machine. The HRM is more accurate because it is strapped on you, while the machine is further away from your heart, and just goes by what info you put in. You HRM is always going to be right.

Good LUck.

HRMs are pretty accurate...I would trust your Polar before a machine any day...I notice that my LifeFitness 9500 elliptical (which is definitely a high end commercial treadmill) is reasonably close to my Polar...but still a bit off...it reads higher calorie burn (kristine--I think you're right--it's further away from your heart so not as exact), but my Nordictrack cx998 always read WAAAAY higher than my Polar even tho it "read" my heartrate and all that crap.  My treadmill was almost always right on.

I agree with others who suggest that you trust the HRM. I once tried to get the elliptical to be more consistent with my HRM and learned that it didn't matter what age or weight I put in the machine - it still showed the same number of calories burned. When I first bought my HRM, like you, I was bummed that my number was smaller than the one on the machine. However, I did start losing weight which seemed to be related to have a more accurate burn number.

 

 

If you are on beta blockers for the hypertension it is harder to get the heart rate in a respectable zone as you discovered while doing the stress test its also harder to keep the pulse rate consistent.  Your HRM knows what your heart rate is where as a machine that although asks for your age and weight and height don't know what you are really working at.  I use a recumbent bike on occassion that picks up my HRM strap but it doesn't ask my age or weight so its calorie burn isn't going to be accurate because a 20 year old with a BPM of 105 isn't going to burn the same as me being 48.

I have a polar F11 that has a fitness test that determines the Vo2 and then calculates how many cals a certain workout is going to burn.  I turn off the "own zone" feature because when I use it I have a very hard time reaching its zones it wants me to do so I stick with the default of 220- age.  

 

The beta blockers are one reason I didn't buy the F11. I didn't want to risk it being inaccurate.

Am I correct in assuming that for a fixed heart rate, say 105 BPM the calorie burn for an 80 year old will be higher than for a 60 year old? I can accept it being different from what the machines yield, but want it to be accurate for me even in with taking beta blockers.

Thanks to everyone for all their comments and help!