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Exercise Calorie Mystery
GrannyMayOz
Posts: 1,051 Member
Here’s something I can’t figure out. I did almost exactly the same run (pretty much) on the treadmill 2 days ago and my phone heart-rate monitor says I burned 588 calories. Afterwards, I saw the settings for the phone and found that it thought I was a 31 year old male, weighing 72 kgs. So I put it right. I'm a 58 year old female who weighs 87 kgs (191 lbs).
So when I did the same run today, same music, same speed and distances; running one song, walking the next, for 30 minutes, it says I burned 302 calories.
How can a fat old woman pumping her heart out burn fewer calories for the same effort as a young, strong male would? His heart would be pumping (relatively) slower to the max it is capable of reaching, while mine’s near max at times. I am completely confused!
The heart-rate readings would have been almost identical for both runs. *Surely* it was a harder workout for the real me than the alleged younger male?
So when I did the same run today, same music, same speed and distances; running one song, walking the next, for 30 minutes, it says I burned 302 calories.
How can a fat old woman pumping her heart out burn fewer calories for the same effort as a young, strong male would? His heart would be pumping (relatively) slower to the max it is capable of reaching, while mine’s near max at times. I am completely confused!
The heart-rate readings would have been almost identical for both runs. *Surely* it was a harder workout for the real me than the alleged younger male?
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Replies
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Was there an adjustment for maximum heart rate? The first measurement (588 cals for a 30 minute run) was complete crap...ain't no human out there gonna burn 20 calories a minute. Only way I could explain such garbage is if the HRM thought the average heart rate near max rate (so it thought that 31 yo dude was "sprinting" for 30 minutes). Garbage in, garbage out.
FWIW, 300 cals in 30 minutes is at least sort of reasonable. 10 cals a minute is still awfully high, but it's at least humanly possible.0 -
What phone heart rate monitor is it?
How does it measure your heart rate?
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Thank you hill8560, I hadn't realised that the 'male' result was GIGO. That helps me a lot! And no, it doesn't have a setting for maximum heart rate. My maximum HR was 178 for the first run and 175 for the second but that's because I do a couple of 150 metre sprints towards the end of the session. Max prior to sprinting is around 165 from the jogging portions.0
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Iron_Feline it's the Sports Tracker app on my phone combined with the official Sports Tracker bluetooth chest band.0
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GrannyMayOz wrote: »Iron_Feline it's the Sports Tracker app on my phone combined with the official Sports Tracker bluetooth chest band.
Cool. I agree with hill8570 the first number of cals was very high.
300 seems more reasonable so I'd just continue with that unless it give you odd results in the future now it's correctly programmed.0 -
Calories burned in running have almost nothing to do with age or how hard the run felt subjectively. The main factors are your weight, the distance you ran, your speed (not very important, though), and your running form (though that's also not very important; it can make a difference of a few percent).
If that 31-year-old male also weighed the same as you, and you both had decent running form, then if you ran side-by-side at the same speed, you'd burn almost exactly the same number of calories. If he's a trained athlete, his heart would be going more slowly, but that would be because it's pumping more oxygenated blood per heartbeat.
It's a common misconception that you burn fewer calories when exercising as you become more fit, because your heart is beating slower at the same speed. I think it comes from the assumption that if an unfit person burns fewer calories at 140 bpm than s/he does at 150 bpm, s/he will also burn fewer calories when the speed that used to require 150 bpm now only requires 140 bpm due to improved fitness. That's not a correct assumption. Higher-end heart rate monitors include information on maximum heart rate, resting heart rate, and fitness level in order to correct for the fact that trained athletes pump more blood per heartbeat.0 -
I can do the same exercise two day's in a row wearing my HR monitor and get different numbers each day. It varies depending on if I'm tired, sick etc.0
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First off, the calories burned has nothing to do with perceived effort. Calories burned is a function of the amount of work performed by moving your body against resistance, not the effort and exertion you feel when you perform it. So a young strong male can perform the same work with less effort, but you both burn the same number of calories. If the work involves moving your own body from place to place, the heavier person actually burns more calories, regardless of the physical conditioning of the person. A person in better shape can of course exercise longer, or accomplish the same exercise in less time, or exercise harder. But if the task is fixed (walking from here to the corner store and back) whether you walk slow and huff and puff or walk briskly while whistling, the calories burned is the same, because at the heart of the matter you are moving your 87 kg body over the same distance either way.
Second, heart rate monitors attempt to estimate the caloric burn by knowing your physical body (male vs female, weight, V02max etc) and monitoring your heart rate to guess how hard you're working. They can be a good guideline, but they are VERY much an estimate, and not a MEASURE of calories burned. To get even remotely close, you have to have all the setting customized correctly for your body, and keep it up to date as your body changes.0 -
HR monitors don't "measure" calorie expenditure. They estimate it... so the more uncertainty you have there, or the more you deviate from the "model" used for the estimate, the more you diverge.
I'll give you an example - let's say you wear your HR monitor watching a horror movie. According to it, your accelerated HR has resulted in significant calorie burn... wrong. Plus, it varies so much if you're tired, if you had caffeine, if you're excited, etc. Not to count that the formulas for max HR, "fat burn" and aerobic zones, etc. are simply generalizations.
Unfortunately, the proof is in the results - for me (cycling), HR calorie estimations are off by about 30-40% on the high side when compared to actual power measurements... that was sobering. So if you are tracking things diligently and you're not losing as expected, your exercise tracking maybe overestimating your physical activity.
For what is worth - cycling, the best estimations are from power meters. Running and walking, you can almost forget about speed - weight, course profile and distance are the most important factors for estimating calorie burn.0 -
Unfortunately, the proof is in the results - for me (cycling), HR calorie estimations are off by about 30-40% on the high side when compared to actual power measurements... that was sobering. So if you are tracking things diligently and you're not losing as expected, your exercise tracking maybe overestimating your physical activity.
Ditto that. Had a month-long weight loss plateau last summer when I starting using HRM calories burned instead of MFP estimates for my mountain bike rides. Threw the HRM into the drawer, and went back to losing weight.0 -
Now if only they could get those power meters to be a reasonable price...0
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Thank you so much everyone for your awesome, intelligent and informed answers. I am a lot wiser now.
(And feeling more kindly towards that imaginary 31 year old man who was going to earn more 'brownie points' than I did for the same job.)
Sometimes I 'eat back' my exercise calories and sometimes I don't. I can now see that even when I do, I should leave room for error on the HRMs part.0 -
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rileysowner wrote: »
Paying your first born will both preserve your appendages, allowing you to continue to ride, and save you money in other ways. You will, however, have to cut your own lawn.0 -
rileysowner wrote: »
Paying your first born will both preserve your appendages, allowing you to continue to ride, and save you money in other ways. You will, however, have to cut your own lawn.
By the time the firstborn is old enough to mow the lawn, the market value is pretty much nil (at least for the males...nobody can afford to feed them). And society is ridiculously biased against parting them out. I just decided to keep mine supplied with bikes so I have someone to chase on the trails.0 -
rileysowner wrote: »
Paying your first born will both preserve your appendages, allowing you to continue to ride, and save you money in other ways. You will, however, have to cut your own lawn.
By the time the firstborn is old enough to mow the lawn, the market value is pretty much nil (at least for the males...nobody can afford to feed them). And society is ridiculously biased against parting them out. I just decided to keep mine supplied with bikes so I have someone to chase on the trails.
If you think the males are a poor return on investment, take a look at the females. Priced out a wedding lately?
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