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Polar HRM - Trusting Calories Burned?

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Polar HRM - Trusting Calories Burned?

Postby bestinred » Mon Feb 18, 2013 11:10 am

Hey! I recently treated myself to a Polar FT4 heart rate monitor as I though it would be a great tool in my weight loss and fitness journey. I have found that it really does keep me motivated and push me to work out harder and longer and has made exercise more fun! But I'm struggling with one thing - do I trust how many calories it says I have burned each workout session?

Today for example - I walked at a relatively fast pace for 40 minutes and according to my Polar FT4 I burned 455 calories. My heart rate averaged at 166 bpm (max was 193 bpm) and I was in the target fat burning zone for 15 minutes of my walk (keeping within this zone is something I have to work on but it's not a priority now - I just want to burn as many calories as I can). I walked up some steep hills so I attribute this to my high heart rate. When I got home I logged my walk on and it was only a 3.4km walk - meaning I walked at a pace of 5.1km per hour. I logged this into CalorieKing (at 40 minutes of walking 5km/hr) and it says I should have only burned 177 calories! This is a massive difference!!!!

I want to trust my Polar as I do believe that measuring my heart rate should be the more accurate measure. And my Polar also has my age, weight, height etc logged into it so it should be accurate right? And calorieking doesn't know how high my HR gets during my workout nor the steep hills I walked etc. But this is such a huge difference in calories burned that I'm now a little scared I'm overestimating my exercise calories and this could be detrimental to my weight loss.

I guess what I want to know is how many of you trust your HRM over calorie estimates such as CalorieKing etc?? I know a few people who trust their HRM over anything and I'd love to just be able to trust it like that but I can't help but question it... Help!

Ultimate Goal = 58kg!!
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Re: Polar HRM - Trusting Calories Burned?

Postby Blitz » Tue Feb 19, 2013 2:04 pm

All these type of things are just a general guide.

There are many variables that can make any result inconstant with previous readings. For example your body may burn calories at a different rate than the day before because you metabolism is responding to the exercise you did the day before! Other variables may be outdoor temperture, fitness, muscle ratio, general health, body cycles, body weight, speed (effort), stress and type of walk circuit (ie flat/hilly/mountainous).

Generally speaking your monitor is accounting for more variables so it is closer to the truth. The other is more generic in nature. My guess the truth is probably somewhere between the two, with the number being closer to the monitor's. Use these things as a guide to help you but don't let them rule your head.

The bottom line is listen to what your body is telling you -that is the most imporant indictor on how you are going.

ps Something to think about...a 3.4km flat circuit and a 3.4km mountainous circuit may be the same length but not the same distance!
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