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SALTATORIA SparkPoints: (1,196)
Fitness Minutes: (622)
Posts: 26
5/13/13 2:51 P

The FT4 only uses your height, weight, and age. I've been thinking of getting the FT7 (?) because it uses your resting heart rate to calibrate better. It might use VO2 as well.

Luckily, I do only use them as guidelines. I never rely on the machines or a HRM. The HRM is just an easy way for me to keep track of my heart rate during my workout, so I know if I need to push it harder or scale it back a bit. It's so much easier to glance at my wrist than it is to hold my fingers to my neck, count, and do math. ;) Plus, my HRM syncs with the machines at the gym, so I can see my heart rate on the display at all times. :)

I was just curious about the discrepancy. It was pretty mind-boggling. My friend uses a Timex and has the same crazy calorie readings, so maybe it's the HRM itself.

CORTNEY-LEE SparkPoints: (67,852)
Fitness Minutes: (69,867)
Posts: 3,526
5/13/13 2:41 P

I don't know what would account for such a large discrepancy. I use a Polar FT4 as well. I would double - triple check the settings? That is crazy!

SLYSAM SparkPoints: (43,184)
Fitness Minutes: (110,991)
Posts: 1,474
5/13/13 2:40 P

This is probably a good example of why you don't want to rely too much on the calorie burn estimate from a heart rate monitor or really any device. Sometimes people take hem calorie burn as a definite fact when really it is estimating calorie burn not directly measuring it. They all have a margin of error. Your two HRM's probably use different formulas to estimate. For comparison purpose it helps if your settings match on both, but even then they will likely be using the data in different ways. The companies general keep their formula a trade secret. I would personally tend to trust the Polar more. The reason, this may be incorrect, but my impression is that Polar has been in the hrm business for a long time and did a lot of testing in developing their products. I am not sure what your FT4 factors in, but I have an old F11 and it factors in my height, weight, age, gender, maximum heart rate, resting heart rate, vo2max and the heart rate throughout the workout. My previous hrm only factored in my height, weight, age, gender, maximum heart rate and average heart rate during the workout. The results were quite variable--if I included warmup and cool down it would actually result in a lower calorie burn since it was mainly using "average heart rate". If I did the same workout and started it after the warmup and stopped before the cooldown it would report a higher calorie burn for a shorter duration. There is no way my warmup and cool down burned "negative calories", it was a flaw in that formula that HRM used. I don't know much about the Timex, but I guess I would trust the Polar most if all your settings are as correct as possible. But remember they are both giving estimates and have some margin of error.

SALTATORIA SparkPoints: (1,196)
Fitness Minutes: (622)
Posts: 26
5/13/13 1:51 P

I had been using a Timex HRM and then switched to a Polar FT4 HRM.

I entered my height and weight correctly on both HRMs and made sure they were both set to Imperial.

While doing Turbo Jam for 45 minutes, the Timex said I burned 948 calories. When I used the Polar FT4, it said I burned 387 calories.

Why is there such a huge difference? The Timex was only a couple months old, so I doubt the battery was wearing out. I bought the Polar because my cat chewed through the chest strap and I liked the Polar's design better. So, they both have new-ish batteries and the same settings.

I'm 5'6" and weigh 296 pounds.

Edited by: SALTATORIA at: 5/13/2013 (13:51)
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