HRM Calories and Long Work-Outs

CarterGrt
CarterGrt Posts: 289 Member
edited September 25 in Fitness and Exercise
I have really enjoyed my HRM and think it is quite good for most of my runs and gym work-outs. However, I would like to get a bit of a clearer understanding on how the HRM estimates work for longer, lower-intensity workouts.

I have read other posts where people write about "backing out your basic calories" to calculate calories while skiing or playing golf or shopping. Here is what I assume, but I am not sure on the math...

I assume that your body burns some number of calories just being alive. When I wear my HRM, it tells me the calories I burned, but (I assume) doesn't back out what I would have burned anyway by just sitting on the couch. With most exercize, this is a trivial amount (again, I assume).

However, I think that when you do some long, sustained exercize like skiing for 8 hours, that you should likely deduct something from the calories reported on the HRM because of the calories you would have burned by just being alive. I wonder about this even more for relatively low intesnsity activities like golf (riding in the cart), for example, or shopping in the mall. You have periods of walking around, but also periods of just standing around. I think the HRM captures this ebb and flow of activity, but I am not sure if it accounts for the amount of calories you would have burned by just sitting on the couch for 5-6 hours.

Anyway, I hope that question is clear. Perhaps I am over-thinking this and need to just go with what the HRM says without any manual adjustment.

Thanks, Carter

FYI, I have the Polar FT80 with chest strap and GPS-G1 if that matters in the answer.

Replies

  • helenium
    helenium Posts: 546 Member
    I'm interested in the answer too. My HRM arrived today and it would be great to know if the calories expended are on top of maintaining all organ functions.
  • WrenLynn
    WrenLynn Posts: 213
    No matter how long of a time you exercise you will need to back out the calories you would have burned anyway. The easiest way to do this is just times 1.5 calories times the number of minutes of exercise. So if my heart rate monitor says I burned 500 calories when I worked out for one hour (60 minutes) I would take 1.5 calories x 60 minutes=90 calories that I need to back out. So when I log my exercise in MFP I will say I burned 410 calories.
  • Jenni268
    Jenni268 Posts: 202 Member
    I've always been under the assumption that if you want something to track LONG periods of time, ie all day or extended activities like mentioned above, that you should invest in a BodyBugg. I think they are more accurate for those types of scenarios.
  • tross0924
    tross0924 Posts: 909 Member
    As far as I know the HRMs don't deduct your at rest calories from the totals they display. Some people say that you should deduct them by dividing your daily maintenance calories per day by 24 to get your hourly couch sitting burn. So for example if your maintenance calories are 2400 per day then you'd burn 100 per hour. Then if your monitor said that you burned 600 calories during your hour of exercise you'd only log 500 (600 displayed - 100 you would have burned anyway).

    I think this would be more important during longer periods of exercise like the OP is asking about. During short periods less than an hour there's some debate. Some say you should deduct it, others say the boost to your metabolism you get for a few hours after you exercise makes up for the difference. Personally I don't deduct them, but every one has to find what works for themselves.

    GL and keep up the good work!
  • CarterGrt
    CarterGrt Posts: 289 Member
    No matter how long of a time you exercise you will need to back out the calories you would have burned anyway. The easiest way to do this is just times 1.5 calories times the number of minutes of exercise. So if my heart rate monitor says I burned 500 calories when I worked out for one hour (60 minutes) I would take 1.5 calories x 60 minutes=90 calories that I need to back out. So when I log my exercise in MFP I will say I burned 410 calories.

    So, that is based on a baseline of 24 hours at 60 minutes per hour = 1,440 minutes x 1.5 = 2,160 calories burned being alive. This makes sense, I suppose, since this is about the amount that MFP tells me to eat if I want to maintain weight.

    This seems like it would be a nice feature for the HRM to do for you, actually. It has all these other bells and whistles, you would think it could back this kind of stuff out.

    Ok, thanks for that.

    --Carter
  • juliapurpletoes
    juliapurpletoes Posts: 951 Member
    I think it is a great question!

    I did alot of looking for info about this myself (ruffled some feathers) and what I found out was that most likely that HRM's and exercise databases for that matter, don't" back out" your exercise calories - (it is complicated programming stuff?)

    So if you don't have alot of wiggle room in your eating and exercise plan then to get the truest accurate reading you should figure out your maintance calories and back them out yourself before logging the activity so you don't over eat them back.

    In your goals section it will tell you how many calories it takes to MAINTAIN your current weight. This is different from your BMR which is truly just breathing and laying about. Maintanance calories are figured using your BMR and activity level.

    I don't know what to do about long sustained low energy activity like golf cart riding.......make a guesstimate?

    I don't think you are worrying for nothing, I just think (like me) you want this program to work for you and not waste your time!!

    Good luck! :smile:
  • stitcherbeth
    stitcherbeth Posts: 52
    I don't add in the lower intensity items such as shopping at the mall, or at Walmart (even though pushing a cart completely full is quite a workout. I just use what I earned from that to allow for any calories I might have been off in my daily count. Sometimes it is hard to get the count exactly right. Also, when I exercise with the HRM and it says like 573 cals burned, I round down and record 500. That gives allowance for things like the basic calories burned for just being alive. I imagine if I played golf, i wouldn't count it if I rode in a cart, but would if I walked it all. Just my opinion.
  • thedragonissue
    thedragonissue Posts: 2
    I'm no expert...

    I don't think they are meant for an exact count of calories burned anyway... it's just a guide. Some are better than others.
    I use a Polar RS300 when exercising and the difference between what it says and what a treadmill says is considerable.

    Polar and most CV equipment manufacturers use a calorie algorithm that is INCLUSIVE of your metabolic rate calories.... i.e. calories burnt in TOTAL during exercise (including those you would have burnt if not exercising).

    I agree it's difficult to gauge the amount of calories burned with the likes of skiing etc... I also don't think HRM's are that great at recording the amount of calories you use to sit still...

    All in all they are really handy for giving reasonably accurate readings and I'm sure if you were to use the readings as they came out you would be fine.

    Hope this makes sense.
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