Heart Rate Monitor - Accuracy?

mogletdeluxe

Hi MFP-ers - your assistance please!

Aaaages ago, I used a heart rate monitor as a one-off during a zumba class. I know I give it some welly, but I had a genuine "jeeez, is that my phone number?" moment.

I decided to then go on the zumbacalories.com recommendation as it short-changed me by about 150 calories, and therefore I felt a little more comfortable having some wiggle room when it came to my food.

I invested in a Polar FT4 this weekend and wore it to this evening's class, and make no mistake I was sweating like a good'un. I come to the end of the class, look at my reading...787 calories. I mean, whut. Too good to be true (and an excuse to get a Twix Mcflurry if I'm given half the chance).

Sounds daft, but how accurate are HRMs? Is there much room for error?

Apologies if this is up there with "what time does the 6 o'clock bus come?" for stupid questions, but it seemed a little too good to be true...

wellbert

The thing to remember is that HRMs don't measure calories burned.
They measure heart rate, then run a formula against it. The closer your activity is to the formula's expectations, the more accurate it is.
Any period of rest while running is still counted as active, moving cardio... for example.

dad106

HRM's when set up correctly(IE age weight height gender) , have a chest strap, and used to steady state cardio(IE walking, running, etc) can be up to 80% accurate. If you add in VO2max or tweak max heart rate, then it goes up to about 90% accurate.

Not sure if Zumba qualifies as steady state cardio... but I would take that number with a grain of salt.

Sweeterescape

I have an FT4 and feel the exact same way!

Have you set it up completely with your age, weight, etc? Make sure to keep that up to date.

Other than that, I'm very interested in what others have to say!

omma_to_3

I've been using mine for months, eating back the calories, and my weightloss has been fine. They are 75% to 85% accurate which is good enough for most people. If it makes you feel better, only record 75% of your time. But for intense excercise(like my running) I count it all!

omma_to_3

Oh also, I set my weight to 10 lbs less than I really am. Then when I reach that, I lower it another 10 lbs. that way I don't have to change the stats as often and I'm slightly underestimating my burn.

mogletdeluxe

Thank you all for your responses, much appreciated. I know any kind of monitor is going to have room for error, but the tips and pointers have been most helpful (particularly regarding setting my weight at 10lb lighter, makes a lot of sense). I think as long as I bear in mind it doesn't give me carte blanche to fill my face, I'll be fine. Still, was very interesting to see that my heart got up to 188 during class!

kitinboots

Having calculated my BMR and divided by 24 I now deduct that number for every hour of exercise. It's pretty close to one calorie per minute, so if I were to get a reading of 787 in an hour, I would log 727, and even less if I still don't feel it's right. You can go with your gut instinct to a certain extent. If I burn 600ish in an hour of running that feels like hard work, then 800 in an hour of zumba that I felt was easy in comparison then I'll log much lower.

omma_to_3

I generally don't worry about subtracting BMR for anything under an hour. An hour and up, I will adjust the number.