HRM is suddenly too kind

CynthiaT60 · January 2014

Hi, HRM wizards/nerds/geeks! Hope someone can help me. I've been using my Polar HRM all along. For a typical workout I get an estimate of 400-500 calories. Works for me.

This weekend I remembered that I hadn't registered my new weight (about 5 kg loss) in the watch. So I did that, and took the resting heart rate test while I was at it, since I've been working out for several months. It gave me a pretty high score, which surprised me, but I didn't think any more about it.

Went to the gym today and the HRM gave me about 800 calories for more or less the same workout (couple new lifting exercises, but they were short). I don't believe a word of it, don't want to eat too much, and manually corrected to about 500 in MFP.

I would think that if I weigh less and have better cardiovascular fitness, I'd be burning FEWER calories, not almost double.

My plan is to do the resting heart rate test again and see whether that changes things, but does anyone else have any other ideas?

Thanks,
Cynthia

BrianSharpe · January 2014

You mentioned "new lifting exercises"......that may be your answer.

HRMs are practically useless for calculating calories for anything other than steady state cardio. I'm going to guess that your heart rate was significantly elevated during the lifting exercises which your HRM would have incorrectly interpreted as a massive caloric expenditure.

Chieflrg · January 2014

Nothing can accurately guess what you burned while lifting weights just because your heart rate went up. An increase heart rate doesn't always mean you are burning more calories, it just means your heart is beating faster. Your calories burned while at a steady state of cardio is the closest and most accurate guesstimate of calories burned.

Also don't forget to subtract the calories that you expend just for normal life functions during your usage of the HRM. I don't believe Polar figures that in when it guesstimates.

GetSoda · January 2014

You mentioned "new lifting exercises"......that may be your answer.

HRMs are practically useless for calculating calories for anything other than steady state cardio. I'm going to guess that your heart rate was significantly elevated during the lifting exercises which your HRM would have incorrectly interpreted as a massive caloric expenditure.

Bingo.

Example, what a HRM reads after a deadlift session is absurd, at best.

CynthiaT60 · January 2014

Thanks for the answers so far! Fair enough as far as measuring lifting; I just use it as an approximation anyway.

Forgetting about the new lifting exercises for a second; it went crazy on the stationary bike as well. (I do about 20 min. of lifting and then about the same on the bike or other cardio.) Usually I'd get about 200 calories for the bike, but today it was more like 500.

AlwaysInMotion · January 2014

I agree, a 300 cal jump on a 20-min bike spin is a bit weird.

I'd trying changing each setting back to its previous value (weight or resting HR, one at at time) and then doing a virtually similar exercise routine (recommend different days, not back to back) to rule out which one might be contributing to the wackiness. I also suggest taking multiple samples of your resting HR and average it before updating your HRM settings.

Another dumb suggestion - might want to check the batteries in the strap and the watch. It could be something silly like that.

CynthiaT60 · January 2014

Thanks, AlwaysInMotion; good suggestion about the average, although I don't know whether I can do that manually, but I'll check.
Batteries *should* be good; had them changed a couple of months ago.

dsimmons107 · January 2014

Polar HRM can be very eradic when the battery is low. They can also be com eradic when the chest strap is old or dirty. If you want a HRM that works with weight lifting you need to take a look at the Polar FT80. It is expensive but it will track your exercise while weight lifting.

I had the same issue last week. I keep spare straps and as soon as I changed the strap and it worked fine after that.

GetSoda · January 2014

Polar also is sensitive to static electricity. If you are wearing moisture wicking clothes that aren't super duper tight, it can pick that up and give you an artificially high heart rate.

SJCon · January 2014

This weekend I remembered that I hadn't registered my new weight (about 5 kg loss) in the watch. So I did that, and took the resting heart rate test while I was at it, since I've been working out for several months. It gave me a pretty high score, which surprised me, but I didn't think any more about it.

Went to the gym today and the HRM gave me about 800 calories for more or less the same workout (couple new lifting exercises, but they were short). I don't believe a word of it, don't want to eat too much, and manually corrected to about 500 in MFP.

I would think that if I weigh less and have better cardiovascular fitness, I'd be burning FEWER calories, not almost double.

My plan is to do the resting heart rate test again and see whether that changes things, but does anyone else have any other ideas?

Thanks,
Cynthia

Guessing you used the Polar app that calculated your Fitness which is an estimation of your VO2 (how fast you move oxygen through your body). The new Vo2 was updated in the polar app and as your VO2 goes up so does your calorie burn which is probably the change. If you use the Digifit App which I think is better than Polar's but it overestimates burn, then their Cardio fitness tests do the same and actualy let you adjust your HR zones as well to account for it. Their website has good info explaining it so you might look it up. As the others have said HRM are not for weight lifting they are for cardio training. The HRM would think you are burning all of that oxygen you are moving but you are only working a few muscles at a time.

CynthiaT60 · January 2014

Thanks for all the answers so far.
So. I calculated the VO2max myself, using resting heart rate (may be less accurate, but because of my knee I can't run or walk any real distance) and manually entered that number in the watch. (Not the app; the watch itself does the calculations, but I suppose it's about the same thing.)
Today the estimation on the bike was much lower. Still about 100 calories higher than the bike itself estimated, but a lot better than it was. I may set the VO2max a point or two lower to see whether it gets closer to the bike, as a general point of reference.

CynthiaT60 · February 2014

Update: did the resting heart rate test again (they call it OwnIndex; it's done in the watch) and it gave me an absurdly high fitness level again. Resting heart rate was 60 (I assume that's accurate) and after the 5 minutes of the test it gave me an OwnIndex of 51, "elite", basically off the charts. Impossible.
Height, weight, age, everything's in there OK. Just washed the chest strap.

This is really starting to bug me. It's like there's something wrong with the algorithm and I can't figure out how to fix it.

Throwing this back in the group again to see whether anyone has any more ideas.

SJCon · February 2014

Update: did the resting heart rate test again (they call it OwnIndex; it's done in the watch) and it gave me an absurdly high fitness level again. Resting heart rate was 60 (I assume that's accurate) and after the 5 minutes of the test it gave me an OwnIndex of 51, "elite", basically off the charts. Impossible.
Height, weight, age, everything's in there OK. Just washed the chest strap.

This is really starting to bug me. It's like there's something wrong with the algorithm and I can't figure out how to fix it.

Throwing this back in the group again to see whether anyone has any more ideas.

So sounds like your almost ready for the Olympics with a VO2 of 51 (LOL).

Don't know what to tell you, sounds like it was based on your RHR of 60, that would be very low for me. I would do it a couple of times and try to mirror the conditions eg. first thing in morning. There are some free smartphone apps to get your HR and you can try one of those at the same time and see if it matches. may want to send it back to customer service or at least give them a call.

ChrisM8971 · February 2014

Hi, HRM wizards/nerds/geeks! Hope someone can help me. I've been using my Polar HRM all along. For a typical workout I get an estimate of 400-500 calories. Works for me.

This weekend I remembered that I hadn't registered my new weight (about 5 kg loss) in the watch. So I did that, and took the resting heart rate test while I was at it, since I've been working out for several months. It gave me a pretty high score, which surprised me, but I didn't think any more about it.

Went to the gym today and the HRM gave me about 800 calories for more or less the same workout (couple new lifting exercises, but they were short). I don't believe a word of it, don't want to eat too much, and manually corrected to about 500 in MFP.

I would think that if I weigh less and have better cardiovascular fitness, I'd be burning FEWER calories, not almost double.

My plan is to do the resting heart rate test again and see whether that changes things, but does anyone else have any other ideas?

Thanks,
Cynthia

I tend to question anything that seems wrong or counter intuitive to me, I think you are on the right track re doing the RHR. However other suggestions on here seem just as valid, particularly about the accuracy of an HRM when lifting

CynthiaT60 · February 2014

Update: did the resting heart rate test again (they call it OwnIndex; it's done in the watch) and it gave me an absurdly high fitness level again. Resting heart rate was 60 (I assume that's accurate) and after the 5 minutes of the test it gave me an OwnIndex of 51, "elite", basically off the charts. Impossible.
Height, weight, age, everything's in there OK. Just washed the chest strap.

This is really starting to bug me. It's like there's something wrong with the algorithm and I can't figure out how to fix it.

Throwing this back in the group again to see whether anyone has any more ideas.

So sounds like your almost ready for the Olympics with a VO2 of 51 (LOL).

Don't know what to tell you, sounds like it was based on your RHR of 60, that would be very low for me. I would do it a couple of times and try to mirror the conditions eg. first thing in morning. There are some free smartphone apps to get your HR and you can try one of those at the same time and see if it matches. may want to send it back to customer service or at least give them a call.

Yeah, I'm a real Olympian, lol. :blushing:
It's just driving me nuts. I sent a message using the form on the Polar site; who knows whether I'll hear from them....
Chris: thanks for your reply as well. I'm not worried about the lifting; I'm just trying to get it to give a reasonable estimate on the stationary bike. It's really a puzzle.

CynthiaT60 · February 2014

So, after two totally unhelpful replies from Polar (why do they just paste in standard answers based on key words instead of READING what you write and responding to it?) I went with the RHR route and counted it myself when I woke up. It was 70, not 60. Plugged that in in the watch and yesterday on the stationary bike the calories were pretty close to what the bike showed. So that was good.

Thinking ahead, I wondered why the HRM would give me 60 for a RHR. Is the unit on the chest strap not working? So I counted manually at the gym and it was pretty much the same HR as what was showing on the watch. It's a mystery.

It's looking better now, but I wanted to post this in case anyone else searches this problem. I'll try it out like this for a while and see whether it all seems reasonable.

HRM is suddenly too kind

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