exercise recording question- no wrong answer! Fitbit/ HRM

tejasmh87

Evening everyone,

I have had my Fitbit for the last two weeks and love it! However, to test the accuracy of it I pulled out my old wrist watch heart monitor for my workout today. Also wanted to see if the watch still worked.

There are my results for calorie burn 40 mins on Elliptical machine at avg. 5.0 speed

Mio Motiva Petitie HRM watch : 1348 cal burned

FitBit: 561 cal burned

actual Machine: 450 cal burned


I know that most exercise machines are not accurate but I included it just for comparison. However, I don't know between the Fitbit and the HRM to record. HRM would make the most sense because it would measure exertion not just steps like the Fitbit.
But its a HUGE gap between numbers.

So any input on people who use both items? Is my HRM wrong or malfunctioning? Between the two what would you trust more? No wrong answers! Just looking for feedback

Thanks everyone!

frankwbrown

Perhaps one difference could be the HRM might be considering ALL calories burned, where the Fitbit might be excluding what would be calories as part of your RMR? I would imagine you would want to go with the calories burned above and beyond what you would burn as part of RMR. You RMR will already be accounted for in your base level calorie goal.

AnnPT77

Elliptical machines can be somewhat difficult to estimate. Just in general terms, I think the 1348 is extremely unlikely to be accurate, for a 40 minute workout. I'm sure that you were working very hard, not doubting that in the slightest! Various things make a difference, but exercise of even 1000 calories per hour is a pretty unusual thing, an elite level of endurance to maintain that high intensity for an hour, for most common kinds of exercise.

If it were me, unless I had a reason to do otherwise, I'd go with the lower of the available estimates, the 450, just out of conservativism. I don't know anything about your current size or fitness level, but 450 would be a high-ish but within the range of plausible estimate for 40 minutes of quite-intense exercise. Frankwbrown is correct that some devices estimate gross calories when what you really want is net calories.

Heart rate monitors and fitness trackers aren't necessarily spot-on for exercise calorie estimates; they have a lot of limitations. They're not measuring calories in any case, they're just doing somewhat-sophisticated estimates. I think too many people believe that their results are certain to be accurate, frankly.

This is a really good article about what heart rate monitors are good at estimating, not so good at estimating, and why:

https://www.myfitnesspal.com/blog/Azdak/view?id=the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472

It's an older article, so some of the specific technology points about then-current devices are out of date, but the general principles are still the same, and worth understanding.

Some high-end fitness trackers now measure more things (still not calories) in addition to heart rate, like arm movements, altitude changes, acceleration, and more. Some ask you to tell them what specific exercise type you're doing. Some let you input your actual maximum heart rate (or something similar like VO2max), if you know it, or have self-tests you can do to get better estimates of HRmax or VO2max. Features like that theoretically could improve those devices' calorie estimates, but it depends on how well the programmers of a particular device took advantage of the data, and on what research evidence they had for doing so. Underscoring: It's still an estimate.

BTW, this is another article by the same fitness professional, about the tradeoffs between HRM and exercise machine estimates:

https://www.myfitnesspal.com/blog/Azdak/view?id=exercise-calories-sometimes-the-cardio-machines-are-more-accurate-404739

heybales

tejasmh87 wrote: »

Evening everyone,

I have had my Fitbit for the last two weeks and love it! However, to test the accuracy of it I pulled out my old wrist watch heart monitor for my workout today. Also wanted to see if the watch still worked.

There are my results for calorie burn 40 mins on Elliptical machine at avg. 5.0 speed

Mio Motiva Petitie HRM watch : 1348 cal burned

FitBit: 561 cal burned

actual Machine: 450 cal burned


I know that most exercise machines are not accurate but I included it just for comparison. However, I don't know between the Fitbit and the HRM to record. HRM would make the most sense because it would measure exertion not just steps like the Fitbit.
But its a HUGE gap between numbers.

So any input on people who use both items? Is my HRM wrong or malfunctioning? Between the two what would you trust more? No wrong answers! Just looking for feedback

Thanks everyone!

What was the heart rate average on both?

Because these are Heart Rate Monitors - not calorie burn readers. So only accuracy is did it read the HR correctly?
And you say Mio watch - so no chest strap? So it's using exactly the same method as Fitbit, light on the back of the watch, right?

They all calculate calories based on some formula - some are better than others - Fitbit better than Mio.

Unless your machine took your weight as a figure, even if it gave watts expended which could be accurate as you'll get - forget any calorie burn formula to be useless unless you happen to match the default weight used when none is input.

The Fitbit is probably inflated too depending on how intense you were going - if this felt like fast walking level of effort - it was inflated estimate.

spiriteagle99

I would go by the machine in this case. 1) If in doubt, I usually choose the lower estimate rather than the higher. 2) The machine knows the intensity of your workout and how far you went. The watches know how much effort you expended, but your HR can be inflated because you are out of shape or the room was hot. 1300 calories for me would be a more than two hour run, certainly not a 40 minute workout.

I have an exercise bike. When I work out on it, I use the machine's number rather than MFP or my watch because it knows how much intensity I did (i.e. was I cycling at 0 or at 6) and how many RPMs. MFP just knows how much time I spent, not how hard I worked. In an hour my husband will go about 5 miles while I go 23. Not the same calorie burn, but MFP might say they are the same, and since my husband is out of shape, a watch might say they are the same. My watch gives a very low number after a workout because my HR doesn't go up much when I'm cycling even when I am working hard.

cwolfman13

Nobody on this planet is burning 1348 calories in 40 minutes of elliptical. Nobody. A HRM doesn't measure exertion...it measures heart beats and uses that as a proxy for exertion, however, if you have a higher than normal HR or are just very out of shape, it is going to exaggerate calorie burn as algorithms in a HRM assume a population average HR and some measure of base fitness.

For reference, I'm a cyclist...1348 is around what I would burn during a 1/2 century (50 mile) road ride being on a bike for roughly 4 hours or more. Without knowing your stats, 450 is within the realm of possibility, but seems a bit high as well...but I'd go with the most conservative estimate. None of this is an exact science.