HRM question - why do I burn so much less than my friend?

jett254

I'm hoping someone can help me understand my HRM. My friend and I both have Polar HRM (FT7). We both wore them to the same group fitness class, which was a combination of high impact cardio and sculpting with bands.

I burned 275 calories and she burned 650 calories. We were both working hard. I weigh about 99 lbs and am 5'1''. She probably weights at least 40 lbs more than me and is a few inches taller. I'm definitely more active. My average heart rate for the session was around 125 and max was 160. Hers was more like 145 average (I can't remember the exact #'s).

So, is the difference only based on the fact that I'm smaller? Does it indicate I could be working harder in class? Do I need to adjust my settings at all on my HRM?

I'm hoping someone understands these things better and can help me!!!!

Thanks in advance!
Jen

mmapags

That's a very big discrpeancy! Maybe one of you doesn't have the HRM set up properly? If not that, then it is that you are more fit than her and you are smaller than her.

cmriverside

The settings could be entered incorrectly, she is larger, you may be more cardiovascularly fit. Age plays a part, too.

auzziecawth66

The taller you are and the more weight you are carrying means the harder your muscles have to work to move that mass. I can bust my *kitten* for an hour and have never burned over 400 calories (according to my hrm) since I'm only 5'1.5". It's unfair but a fact of life being short lol.

maegmez

Resting heart rate can change things. If you have a lower resting heart rate, you will have to work harder to get your heart rate up.

Age and weight factor in too but that is a huge difference. Can you change fitness levels on the polar? If so, make sure you're both in the right level.

bokodasu

Plugging in the numbers you gave in a calculator, guessing that you had a 60-minute class, gives 465 for you and 560 for her, assuming she's the same age as you and the weight you think. Which sounds about right. Ish.

So... lots of options.

1) Your numbers are wrong - either you're misremembering something, or she weighs more than you think she does, or one of you is fitter than the other and has their HRM set to reflect that
2) She's significantly younger than you
3) Someone's HRM is set wrong (possibly both, depending on how many settings your HRM has)
4) Someone's HRM is malfunctioning - it lost contact, or needs a new battery, or whatever.

So yeah, there should be a biggish difference, but no, not *that* big a difference.

jett254

Wow, thanks for all the replies. We are the same age, and I've had my HRM for a few months and that burn (~300 calories for a class that has a combination of sculpting and cardio or a maximum of 450 for an hour of kickboxing) is consistent for me. Her HRM is newer, she just started wearing it. There really weren't many setting though, and neither of us messed with the advanced settings so it is just height, weight, age as far as I recall.

I am definitely fit - I work out 6 days per week and she is just getting back into exercising. It is just frustrating to have my burn be so much lower but I can totally accept it if it is just because of my size. I just wanted to know if I should either by adjusting something or it is a sign that I'm not working hard enough (which I have trouble believing because I'm in the front of the class and busting my butt the whole time).

maegmez

If it helps, I weigh 185 pounds but burn calories to the tune of someone that weighs 155 pounds. My resting heart rate is 53 so really have to push hard to burn the calories.

I was bummed at first, I knew it would get harder but not this soon. But then I opened my eyes! My heart is conditioned for health now!

Mokey41

She's bigger so she burns more, you're smaller and more fit so you burn less.

maegmez

She's bigger so she burns more, you're smaller and more fit so you burn less.

Not always the case, read above.

jett254

Thanks everyone. I guess I'll just have to settle for what I burn and remind myself that I'm fit!

twinkychops

The taller you are and the more weight you are carrying means the harder your muscles have to work to move that mass. I can bust my *kitten* for an hour and have never burned over 400 calories (according to my hrm) since I'm only 5'1.5". It's unfair but a fact of life being short lol.

exactly, I have this trouble, I'm only 5ft 2 and my taller friends burn a lot more than me, also since I've lost weight my burns are smaller and as they weigh more they burn more on average x x ( hope that made sense, it did in my head! hahah )

4_Lisa

She's bigger than you are, and less active, therefore her heart was working harder. The smaller and fitter you are, the more efficient your heart pumps, therefore it takes more to burn calories because you are more fit.

segooey

A teammate and I wear our HRMs while playing hockey. He is a few years older and about 100 pounds lighter than me and struggles to burn half the calories I do. I burn 1500-1700 per game, he's usually between 600-800.

The general consensus on the team, though, is that he's just not hustling.

SJ46

She is bigger and you are much fitter. I am small and fit, I generally burn a lot less than others in the same class when we compare HRM calorie estimates.

mmapags

Thanks everyone. I guess I'll just have to settle for what I burn and remind myself that I'm fit!

When I look at your profile pic, you are lean and fit. Why be concerned with calorie burn? There are many benefits to exercise like increased lean mass, hormone health, increased bone density etc. Calorie burn is only critical if you are trying to lose weight. I think sometimes the design of this site lends inself to some of us being overly focused on calories. I think that is good on the intake side. On the calorie burning side not always.

I tend to favor the TDEE - x% method with no counting exercise calories and just using an activity level to determine TDEE. I think it makes us less obsessive about what our buns are. When you take into account things like EPOC (the calorie afterburn from more intense exercise) it's all just an estimate anyway.

eowynmn

When I first got my polarFT60, it was giving me half the calories it gives me now. I had not done the fitness test yet, once you do, if you are not fit it bumps you up. For my age and weight it doubled my burn once it realized how out of shape I am. Your fitness level really does play the part, so if you have both completed the fitness assessment on your hrm then it very well could be correct.

jett254

I don't think the FT7 has a fitness test. I've looked at the manual.

And yes, I agree - MFP makes one overly obsessed with the calories. I'm working on not being so obsessed, but I continue to wear my HRM because I find that it motivates me to work harder and push myself during workouts. Hopefully that makes sense. I really appreciate hearing other people experiencing the same issue that I am experiencing. I'll admit that it is a little frustrating to see it say I burned under 300 calories when I push myself as hard as I can for an hour. But whatever....I've been gradually upping my calories and I got a bodymedia fit which has been very consistent for my workout burns but has made me realize that I burn a lot more than I was giving myself credit for outside of the gym.

Azdak

When I first got my polarFT60, it was giving me half the calories it gives me now. I had not done the fitness test yet, once you do, if you are not fit it bumps you up. For my age and weight it doubled my burn once it realized how out of shape I am. Your fitness level really does play the part, so if you have both completed the fitness assessment on your hrm then it very well could be correct.

??? The exact opposite is what should happen. If your fitness level increases, and you update the number in the FT60, it increases your "scale" so that you now burn more calories at the same heart rate.

I suspect the HRM had a default fitness level setting that was a bit lower than what you got on the fitness test, and when you did the test, it actually increased the fitness level programmed into the HRM.

Azdak

You DO NOT burn more calories because you are less fit. Absolutely not.

I don't have time to go into details, but the answer is just no, no, no, no, no, no, no.

The decrease in calories burned displayed on an HRM as one trains and improves fitness is a HRM anomaly. It is an error in the HRM, not in your body.

jett254

And that is exactly what I was wondering...if I actually burn less calories or if the HRM just thinks I burn less calories since I am more fit and my heart rate doesn't get as high as it used to. So complicated!