Garmin Calorie Burn Estimates
SteveTries
Posts: 723 Member
I'd love to hear from Cyclists about their thoughts on calorie burn.
I am very new to riding, but have been running for a number of yearse and have come to have faith in my Garmin's calorie burn estimates. Cycling (at least the way I do it) I perceive as having a much lesser effort than running. I'd say it's half as taxing for me.
Yet my garmin (which is reading my HR and knows I am cycling [though doesn't know the terrain, nor if I'm on a road or mountain bike]), is generally coming in at ~75% of the calorie burn for a comparable duration run.
I realise the absence of science in my argument - it just instinctively feels off.
Here's an example from this week:
* 1hr 2m Mountain Bike on Road and Train - avg HR 117bpm
* 57 min run at moderate pace - avg HR 136bpm
For reference, avg Resting HR ~ 39-41bpm
Anyone researched this already or has a point of view?
I am very new to riding, but have been running for a number of yearse and have come to have faith in my Garmin's calorie burn estimates. Cycling (at least the way I do it) I perceive as having a much lesser effort than running. I'd say it's half as taxing for me.
Yet my garmin (which is reading my HR and knows I am cycling [though doesn't know the terrain, nor if I'm on a road or mountain bike]), is generally coming in at ~75% of the calorie burn for a comparable duration run.
I realise the absence of science in my argument - it just instinctively feels off.
Here's an example from this week:
* 1hr 2m Mountain Bike on Road and Train - avg HR 117bpm
* 57 min run at moderate pace - avg HR 136bpm
For reference, avg Resting HR ~ 39-41bpm
Anyone researched this already or has a point of view?
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yep
I've got a power meter on my road and cyclocross bikes.
the Calories calculated by my Garmin 520 via heart rate are within +-3% of the total energy expanded as measured by the power meter.
Most studies show that the human body is around 18-26% efficient at converting fuel into muscular effort - call it 22% on average.
4.186 kJ = 1 kcal = 1 Calorie
or put another way, 1kj = .238 calories.
so, it's "near enough" to say that Kj's expended on the bike will be pretty close to the Calories you burn.
as I'm fat and unfit, i'd expect that I'm actually on the low side of the efficiency, nearer 18%, so I'm very probably burning more Calories than the Garmin says - which means if I work to the Garmins figures I'm on the safe side for weight loss.
You don't say which Garmin you have - I know some of the Garmins could be "calibrated" if you went through some testing processes - https://www.dcrainmaker.com/tag/new-leaf - as always DC Rainmaker has something to say on this. I know my Garmin 810 was newleaf compatible, and the calibration DID make a big effect in the accuracy. I did some work with a couple of guys to "reverse engineer" some of the processes in the newleaf thing - i'll see if I can dig out some of the threads that referred to it after this post.
One thing to make sure you've got set properly, is your height, weight and heart rate zones for cycling (which can be different to running BTW - cycling hrMax will be lower on the bike as it's not a "full body activity").
But short answer is, if you're not sure about the garmin figures, get a power meter and use the Kj's figure as your calorie burn.
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I use a cycling specific Garmin (Edge 1000) so it does know the terrain so can estimate power to a degree. (I don't use a power meter outdoors.)
Personally I find the calorie estimates entirely reasonable/believable/usable. They stand up to comparison well when I train indoors with a power meter equipped trainer.
The estimates also are very similar when I feed the data through into Strava although some differences on rides of differing intensities.
HR on its own isn't a great way to estimate calories for many people. Your exercise HR might just not be very "average", there might be external influences (heat, dehydration, caffeine, stress...) that raise your HR out of line with energy expenditure.
You could join up to Strava for a free comparison with what your Garmin is telling you.
"Cycling (at least the way I do it) I perceive as having a much lesser effort than running." - That's a choice though, you could go faster or climb more hills.
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Really helpful, thank you both.
@TheBigYin, I use a forerunner 645M and will look into the calibration.
I think a Garmin Edge 520 plus is the next purchase for me, with perhaps a power meter to follow.0 -
Based on my logging and weight loss/gain history, my garmin has been accurate enough for me. However, I don't have any measurable way to verify accuracy... I just know that if I log garmin calories to MFP, then eat what MFP tells me to eat, I gain/lose/maintain as MFP says I will. In my book, that's good enough.1
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HR on its own isn't a great way to estimate calories for many people. Your exercise HR might just not be very "average", there might be external influences (heat, dehydration, caffeine, stress...) that raise your HR out of line with energy expenditure.
Amen to that - i'm one of the "outliers" here... After a bout of pneumonia which caused damage to my heart, I've had a couple of stents fitted, and i'm on Beta blockers. These mean my HrMax is chemically limited to around 154 (that figure was attained in a medical environment - ergometer ramp test with a ECG machine in situ, and 2 nurses with the "crash cart" in attendence in case I fell off my perch during the test - so while it's "attainable" it's not the wisest thing to hit anything above 150 while "out on the road".)
So i've a HrRest of 43 and a HrMax of 154 - compared to pre-illness of 48 and 186. Now, the thing is, because the maximums are really what's being "knocked off" by the beta-blockers, the conventional percentage "bands" for heart rate effort - which is what the garmin uses to calculate calories - aren't quite right for me - which is why I ended up getting power meters for my two main rides.
I said in my original post that for me, the garmin is =-3% to the power meter. What I omitted to say (as it wasn't really pertinent to my original post) was that I've tweaked my effort banding from the conventional 50,60,70,80,90,100% to something that reflects how I "run out of steam" really quickly at the top end... (50,60,75,85,94,100% in my case, partly by trial and error, partly by working with the lactate threshold information I also got from my hospital torture tests...)
But, in fairness, if you're relatively "normal" build and fitness, with no wierd medical problems, then the 520 will probably be "near enough" - if you're really worried it's over reading, just say you're 5kg lighter than you actually weigh.
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How are you reading your HR? You say your Garmin tells you - is that from a watch/wrist based device? these can give terrible results for cycling...running they seem to be fine but for cycling the date from a wrist based device is all over the place (See Dc rainmakaers website, click on any review for a wearable and scroll down to the cycling bit - they are all the same).
if you want to measure Hr while cycling, a chest strap is the better way to do it (the data can still be sent to the 520 if you get one) :-)0 -
Really helpful, thank you both.
@TheBigYin, I use a forerunner 645M and will look into the calibration.
I think a Garmin Edge 520 plus is the next purchase for me, with perhaps a power meter to follow.
Get the power meter, skip the Edge.2 -
How are you reading your HR? You say your Garmin tells you - is that from a watch/wrist based device? these can give terrible results for cycling...running they seem to be fine but for cycling the date from a wrist based device is all over the plac
I use a Mio Link wrist-based HR monitor (bought 2nd-hand from the estimable BigYin) linked to my Garmin 1000, which I'm very pleased with. I have no real way of telling whether it's accurate, but it corresponds pretty well to my perceived effort, and is very consitent in the readings from ride to ride and in all kinds of weathers from sub-zero to blazing hot, dry to torrential rain, hard (by my standards) fast cycling to more restrained long(er) rides.
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Glad the Mio's still working well Steve
The MioLink is one of the better optical sensors - mainly because it's not a wristwatch/wristband with a display, so there's no temptation to wear it near your wrist-joint. The optical sensors work better on the bike if they're around 3-4" up from the wrist joint - basically, out of the area where the movement of the joint either wrinkles or moves the skin. The other good optical sensor is the Scosche Rhythym+ which works on the upper arm or just below the elbow on the upper forearm...
okay, they're probably not quite as accurate as a chestband, especially in summer if uncovered and the external light gets in at the sides, and I found the MioLink much more prone to wierd dropouts when riding the 'crosser or mtb offroad - probably as i'm a fat git and I still "jiggle" a bit - ripped racing snakes wouldn't have that issue.
But, to be honest, if it'd not had ONE failing, I'd have kept it and be using it myself - the problem was, at the time I got rid, I was suffering from occasional exercise induced A-Fib - after having a heart procedure, i'd occasionally get the odd "flutter" where the upper and lower heart chambers would go out-of-synch for a couple of minutes. Chest bands (basically being a low-sensor count ecg) picked this up and showed the HR hitting anything to 280, the optical sensors basically didn't. As the reason for wearing a HRM at the time wasn't training, it was survival, the optical sensors weren't "fit for MY purpose" and hence Steve got his deal...
(incidentally, I'm happy to add, I've not had any A-Fib incidents for over a year now - touch-wood - so I'm back to using HRM's for their real purpose...)
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I've been wondering about this too. Because the exercise calories are added to my daily allowance it does matter. And I'm 'earning' loads because I train 16 hours or so a week. For example, my ride yesterday added 4,977 to my allowance, and that's a lot.0
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@bikeracerI've been wondering about this too. Because the exercise calories are added to my daily allowance it does matter. And I'm 'earning' loads because I train 16 hours or so a week. For example, my ride yesterday added 4,977 to my allowance, and that's a lot.
Just over 3hrs to burn almost 5,000 cals - that's one hell of a lot!
By rough maths that's about 440w average, Geraint Thomas will be quaking in his boots.
Do you use a power meter?0 -
@bikeracerI've been wondering about this too. Because the exercise calories are added to my daily allowance it does matter. And I'm 'earning' loads because I train 16 hours or so a week. For example, my ride yesterday added 4,977 to my allowance, and that's a lot.
Just over 3hrs to burn almost 5,000 cals - that's one hell of a lot!
By rough maths that's about 440w average, Geraint Thomas will be quaking in his boots.
Do you use a power meter?
I was just thinking that...
lets put it this way, the only ride i've got in the books with a "proper" powermeter, that burned that much - 4.91kcals - was 130km, over a duration of 5h38m (ok, so I'm sloooow) at an average power of 233w...
(that was a while ago, and as you've probably realised from the lack of speed, i'm a "big unit..." )
but, those "measured figures" pretty much back up @sijomial 's back of a *kitten*-packet maths...
so - if the figures ARE right, and you averaged 440w for 3 hours, that'd put your FTP around 550w, so if you weigh under 90kg, you're pretty much in Lance Armstrong Territory and should be sending your CV to world tour teams right away...
OR
the calorie figures (and the power figures they're based on) are a load of bollocks.
one or the other. I'm not sure which, obviously.
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love how the swearie filter takes out a coloquialism for cigarette packet, and leaves the word bollocks btw. Same kind of cockwombles that mangle the word Scunthorpe...
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