Calories burnt fitbit vs hrm?

[whome]

I recently bought a Polar FT1 heart rate monitor because the cheap SmartHealth watch I had required me to stop running and push a button and wait for it to read. this took a minimum of 30 seconds and usually 45 to 60 seconds - so I knew my rate was dropping and couldn't be accurate. Anyway, now I have average HR and time spent to figure calorie burn and the numbers seem too fantastic to be believed! e.g. Today I ran 3.95 mi in 44 minutes with avg HR of 173 - the calculator formula I have found says this is 104% of my theoretical max of 166 (60 years old 145lb male) and calculated my calorie burn at 833, while the Fitbit activity log apparently thinks I am walking 10 minute miles and calculates my calorie burn as 402. If I edit the acitivity log (actually enter a new one) using the same time and distance it drops my step count and calories burnt presumably because of my stride length. Is there some setting I am missing that will bring these two numbers closer together?

[trainer]

I can't answer your specific question, but I am a personal trainer and know a fair amount about age, heart rate, etc and I would STRONGLY suggest you talk to your dr about the results you posted here. I have been taught that you shouldn't let your hr get above your max, esp male, esp over the age of 50. If you were my client I would tell you to slow down or see your dr to get permission to do this. Just my 2 cents...

[whome]

Thanks - I plan to see Dr about getting a max test done - that is a "theoretical" max - I also want to get a proper Body fat% measurement - my scale says i am about 10% and I find it hard to believe that I am in that good of shape

[Colinm39 · Accepted solution]

You enter a calories only activity but I would think the HRM is being generous and the Fitbit tracker appears to be correct. No need to add a new record. It is all about Rate of Perceived Exertion (RPE)  

 I had an instant recently where my HRM measured my HR on a hot day and my HR was double my  resting HR the of 53 and I was probably lacking fluid. I was only watching TV . Hence my comment about.RPE

[whome]

Thanks Colin - sounds reasonable - I am still planning to see if I get get Max HR and VO2 max measured -

Craig

[Mary]

I had a cardio stress test done and got my HR to 200 at age 44.  They thought nothing of it.  Some of us just have genetically faster HR and the estimators don't work well for us.  A better estimate of your max HR is the max you've seen on your Polar, then do your % ranges from that.  

Just glancing at this table below and seeing what the activities database give me for a 45min run at 6mph, the Fitbit data seems fairly close?

http://www.mayoclinic.org/healthy-living/weight-loss/in-depth/exercise/art-20050999

[slysam]

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@whome wrote:

I recently bought a Polar FT1 heart rate monitor because the cheap SmartHealth watch I had required me to stop running and push a button and wait for it to read. this took a minimum of 30 seconds and usually 45 to 60 seconds - so I knew my rate was dropping and couldn't be accurate. Anyway, now I have average HR and time spent to figure calorie burn and the numbers seem too fantastic to be believed! e.g. Today I ran 3.95 mi in 44 minutes with avg HR of 173 - the calculator formula I have found says this is 104% of my theoretical max of 166 (60 years old 145lb male) and calculated my calorie burn at 833, while the Fitbit activity log apparently thinks I am walking 10 minute miles and calculates my calorie burn as 402. If I edit the acitivity log (actually enter a new one) using the same time and distance it drops my step count and calories burnt presumably because of my stride length. Is there some setting I am missing that will bring these two numbers closer together?

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Others that have posted always give well thought advice and I haven't read their responses yet so this might be repeating what was said. But I wanted to reply before I forgot what you wrote. Heart rate monitors that estimate calorie burn are actually estimating oxygen consumption based on your heart rate and the calorie burn estimate comes from their estimate of oxygen consumption. In a lab they would make you wear a heavy facemask/helmet that analyzed the air goign in and out (and they would clip your nose shut--at least that is what they did to me when I was in a research study). The assumptions are based on your profile stats that your HRM factors: usually height, weight, age, gender. The use age to estimate your "maximum heart rate" and to make assumptions about your fitness levels. People who have better lung capacity can burn more calories than people with worse for the same exertion level. The exertion is estimated usually by what percent of your maximum heart rate your average heart beat for the workout reaches. So you are correct that a continuous monitor is better than one that makes you stop for a reading. But... Your maximum heart rate is too low for your capability so likely the calorie burn inflated. in real life, there are variations beyond age in maximum heart rate and you should not be reaching your maximum during an aerobic workout that you can sustain for a period of time. I think fitbit's estimate is closer to the truth in this case. Try to get a better estimate of your maximum heart rate--if you are walking you shouldn't be anywhere near it. Some more sophisticated HRM's factor in more information including resting pulse, Vo2Max (a measure of lung capacity), fitness level, maybe even bodyfat percent (leaner people likely burn more for the same exertion--well, people with more lean mass the smaller one is the less effort required to move their body through space). Most basic HRM's use height, gender and age to guesstimate at lean mass.

[whome]

@Mary - Thanks - That eases my mind a little

@slysam - thanks - one of the things is that I am running but for some reason the fitbit app seems to think I am walking - if I edit to show I am running it reduces my steps and calorie burn - Oh well - if this is the biggest problem I have today, it is going to be a very good day

Craig

[Mary]

I'm curious what makes you think the Fitbit thinks you're walking?

[slysam]

Just a rule of thumb that I would not fully trust... Some sources say on "average" people typically burn about 100 calories per mile whether walking or running. Running would cause it to happen sooner than walking presumably you would be moving faster. Fitbit credits me with less than 100 calories per mile (about 95 calories for a 4mph speed mile), but that may be due to my profile stats and low BMR. A ten minute mile seems more like jogging to me (though I am only 5' 1"), when I walk 4mph I can pass slower joggers on the sidewalk so some jog slower than that obviously. A ten minute mile would be 6 miles per hour. If logging running actually decreases your calorie burn it sounds like fitbit was probably crediting you for running. Whether it credits you for the correct speed, is a different issue not related to calorie burn. That has to do with your stride length settings. Since other calculators and GPS apps do base calorie burn for distance activities like walking and running, calibrating your fitbit stride can help in comparing your fitbit calorie burn to other sources. But for non-loged activity it is more the steps per minute, your stats and maybe something else in the movement data like impact. Though this has nothing to do with your HRM. I found after I got both my fitbit settings and my HRM settings closer to correct for me--the calorie burns for step-based activities became more similar to each other. On my HRM the settings in question: height, weight, age, gender, resting pulse, Vo2Max and maximum heart rate. On Fitbit: height, weight, age, gender, and stride length settings for walking and running (I don't think this effects calorie burn, but having close to accurate speed and distance just made it easier to compare to other sources. MY HRM is a heart rate/GPS app so for walking and running distance and speed may matter).

[whome]

@mary - when I logged the activity as running using the distance measured by the fitbit it decreased the # of steps taken for the distance - running stride longer,therefore less steps for the distance, ergo it thinks I am walking - but I could be mistaken - 

@slysam - I have measured my strides on a 400 meter track using the fitbit to count steps around both walking and running (jogging if you prefer) - thank goodness I am not worried about this, just curious, kind of -

for example - today I ran 3.81 miles in 40 minutes and the fitbit creditted me with burning 362 Calories - I then walked around cooling down 0.8 miles in 27 minutes and supposedly burnt 118 Calories - when I subtract the 1 Calorie per minute Fitbit assigns me for BMR/RMR  and figure out per mile Calories it works out to 84 per mile running at 10 minutes per mile and 112 per mile at about 30 minutes per mile walking - doesn't make sense to me - but then again, neither do lots of other things

Hope everyone had as nice a day as I did -

Good luck to all

Craig 

[Dominique]

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@whome wrote:

I also want to get a proper Body fat% measurement - my scale says i am about 10% and I find it hard to believe that I am in that good of shape

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Does your torso looks like that of the 10-12% guy on the photo included in the following link:

http://www.builtlean.com/2012/09/24/body-fat-percentage-men-women/

[Dominique]

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@whome wrote:

I plan to see Dr about getting a max test done - that is a "theoretical" max

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If your HRM can talk to a compatible smartphone and you are fit enough, you can perform the Cooper running test (all out for 12 minutes) with the Digifit iCardio app. This will give you your actual max HR, as well as other useful information about your personal HR zones, VO2 Max. etc.

Your max HR may very well be above the value derived from the standard formula (220 - age), but I'd say 173 bpm when running at 8.5 km/h sounds quite high for a 60-year-old guy.

[whome]

No, I don't look like that - lol -  -

I was down to 163 avg yesterday and in my defense it was 80 degrees F the day I was so high - that's 26.6 C for you I guess - maybe that had something to do with it

[Colinm39]

I have two HRM's, an MIO Sport touch on HRM as my watch for my opportunity walking and a Polar rs300x for the heavy, intense stuff. Both are accurate with calories against my multiple *** Fitbit's. The accuracy is compared to a moderate to brisk walk on the Fitbit's at about 3.8mph.

I had to calibrate my Polar because it has a Vo2 setting and because I have a slow HR 58 bpm while typing this, 53 bpm while resting and can get down to 42 bpm sleeping. The Polar Vo2 test relies on lying for a few minutes, and my Vo2 test comes out at Athletic - Elite.. No way... I had a stress test a few years ago and my Vo2 was average to good.

So I used the Rockport walking test  and confirmed that was my setting and then adjusted the Polar, to that and hence both HRM's have similar readings, even on a stationary bike.  The HR taken is at the precise second you stop the 1 mile walk.  The first calculator gives you an idea of effort and METS.

Rockport link

Treadmill Rockport Link

*** As posted elsewhere I have multiple Fitbit's because each was in a stage of destruction and I purchased another so that I wouldn't be without, so they became comparison devices.

[whome]

Thanks Colin - I will have to take that test when I can get by the school with track next weekend

[Heybales]

If you do know the distance that you covered, and the time, you know your pace. You know your weight.

This formula is more accurate than HRM is going to be, even nicer ones that have correct stats for HRmax and VO2max.

http://www.exrx.net/Calculators/WalkRunMETs.html

You want the Gross option to compare to what the HRM would be reporting, or to log to replace what Fitbit came up with, because that includes the resting calories.

Well, studies have shown that walking between 2-4 mph level, and basing calculations on formula's, is much more accurate than the 15-25% accuracy a HRM may get if properly set up. And that's 15-25% either direction, not just inflated. 

http://www.ncbi.nlm.nih.gov/pubmed/15570150 

(4.2 kJ is 1 calorie. Notice the energy expenditure on treadmill and track is almost equal.) 

That test Walking was 3.2 mph level for 1 mile for 19 min, calculation was 3.4 calories higher than tested 81 cal, or 4.2% higher. 
Running at 6.3 mph level for 1 mile for 9.5 min, calculation was 4.8 calories lower than tested 115 cal, or 4.2% lower. 

Also, as someone mentioned, the HRM's can't tell in inflated HR for some valid reason, like caffiene, stimulates, or heat-elevated, or dehydrated. All reasons the HR would inflate and not be valid measure for the level of effort you are doing.

But with that knowledge, it's the best we got without wearing a face-mask and backpack air bag around.

10 min/miles can easily be running - and appears to be your pace. Where does it say walking vs running?

[Colinm39]

@Heybales Great information.  It will be appreciated by all. I get my speed.from the pace graph from my v's a was y timed activity or average it by time and distance. 

[whome]

@Haybales - Thanks - that calculator works out a 517 burn for a run that the Fitbit shows only 447 - It may be that I was losing weight faster than expected over the last 3 months because I was burning more calories than the Fitbit system calculates for me -

 The activity tracker shows a walking stick figure instead of a running one (as it does if running is manually entered) but that might be misleading