HRM Questions Thoughts??

I would always trust a chest strap over a watch...the device is much more accurate. Polars are known for accuracy.

I have a Polar FT4 and did an Insanity workout on Monday and burned 580 calories....I did the SAME workout today and only burned 535....it's all heart rate and effort based. What "feels" the same to us isn't always what's happening inside our bodies. I don't think you have to determine which one was right....just know it will probably be different every day....and if you wear the Polar for a few days I would bet you would get a variety of numbers. Good luck!!!!

I did my same run as always watched my heart beat bpm as I went and it was the same as always but instead of burning my normal 380 to 400 I only burned 340? I know its not a massive difference but still it makes me wonder?? Which would you guys trust??

Most heart rate monitors overestimate calories burned. I would trust the lower number. How far did you run? If you're running at a moderate pace, your weight in kg is about equal to the number of calories you burn per kilometer. I currently weigh 87 kg, so to burn 400 calories I'd need to run about 4.6 km.

How do you know that they overestimate calories burned?

From my weight loss my polar has been pretty spot on, even when it tells me I have burned 800 calories from Spinning...I have never felt that my Polar was off by all that much. The key though is to realize that even if you were not exercising you would be burning calories. so I never eat more than half my exercise calories...
unless I am really hungry or just want to cheat :drinker:

That's a fair question. First, I've noticed that my own HRMs have varied wildly. The Timex one that I started out with, and the Garmin Forerunner 410 that I used for running these days, both give much higher calorie readings than my Garmin Edge 800, which combines HRM data with speed, elevation, and my and my bike+gear's weight when it estimates calories consumed. If I use both Garmins (they are linked to the same chest sensor), the 410 gives a calorie count that's about 30-40% higher than the 800, from the same heart rate data, and with the same user data programmed in (age, weight, maximum heart rate).

To take a concrete example, my wife and I went for a 38-mile bike ride yesterday, with about 1200 feet of climbing, at an average 12 mph speed. My Edge 800 claimed I consumed 999 calories, while her Polar HRM claimed that she consumed over 1,700. Since I weigh more than she does, I should have consumed more energy than she did; I'm probably slightly more biomechanically efficient when cycling than she, and I have a slightly more aerodynamic position on my bike, but that shouldn't account for more than a 5-10% difference.

Peer-reviewed research also supports the claim. One study of the Polar F6 showed that, even calibrated with subjects' actual VO2max and HRmax, it overestimated energy expenditure by 27% (http://www.ncbi.nlm.nih.gov/pubmed/21178923). An earlier study showed that the Polar S410 overestimated energy expenditure in women by 12% (http://www.ncbi.nlm.nih.gov/pubmed/15292754). Another study found that the Polar S810i overestimated expenditure when exercising lightly but not moderately (http://www.jssm.org/vol9/n3/21/v9n3-21abst.php). The research seems to suggest that HRMs are less accurate for women than they are for men.

The study by Keytel et al (http://www.ncbi.nlm.nih.gov/pubmed/15966347) that produced a widely-used formula found that it was reasonably accurate for groups when VO2max had been measured, but less accurate without measurement of VO2max - in the latter case, over 26% of the variance in energy expenditure was not explained by their equation, which uses heart rate, gender, age, and weight to estimate calories consumed.

If your weight loss matches your Polar HRM's calorie count, then you're fortunate. HRMs are marketed as measuring net energy expenditure--calories consumed over and above your basal metabolic rate, the energy consumed just by keeping the body going and maintaining an even body temperature.