Accuracy of calories burned while biking

[nscrbug]

So I've been using my Garmin Edge 500 for a few weeks now and really like it. I think it's really cool to upload my rides to Garmin Connect and see all the ride data and graphs. The one thing that has me a bit skeptical is the amount of calories burned. I'm just not sure that I trust it, and I'd like to get opinions from others that are using the 500 to see if their results are similar.

I wear the HR strap (and yes, I do have it on correctly, as I've read that this can make a difference), and I wet the sensor patches on it before putting it on. I've entered my profile information correctly - weight/height/gender, etc. So here are the stats from my last 2 rides -

Ride 1
Time - 04:33:17
Distance - 71.05mi
Elev Gain - 659ft
Ave Temp - 56.5F
Avg Speed - 15.6mph
Avg HR - 108bpm
Max HR - 132bpm
Calories - 771

Ride 2
Time - 04:41:32
Distance - 73.33mi
Elev Gain - 1,745ft
Avg Temp - 76.5F
Avg Speed - 15.6mph
Avg HR - 109bpm
Max HR - 144bpm
Calories - 862

FWIW...I'm roughly 157lbs + bike weight (5'6" & 45 yo). I don't know, but the calorie burn seems awfully low for 4+ hour rides. My average HR is low too, which seems odd especially since I feel like I'm working SO hard (it was windy on both of these rides). I can't seem to ever get my HR very high when riding, as is clearly displayed by my MAX HR on either ride. Yet the effort I put out feels like I'm not just pedaling at a leisurely pace, I'm fighting to keep up with my riding buddy who is quite a bit faster than me...so I don't get it. It's kind of discouraging in a way...to feel exhausted/sore after a long ride, knowing you worked hard...then to see the results of your efforts, only to discover that the numbers are disappointing. I can burn an equal amount of calories at the gym doing cardio and weights in half the time it took me to burn the same amount on a 4 1/2 hour ride. I'm confused by this.

Linda

[MaTadams]

The calorie burns seem low to me. I've used a Polar HRM in the past and its estimates were definitely higher than my Garmin, but your estimates seem unusually low. Have you tried any of the online calorie burn calculators to compare?

[amb]

I have a polar HRM that is not near as fancy. It's meant more for fitness classes and such, not biking. Here are my stats from today:

Distance: 24 miles
Total time: 1h:42m (incl stops)
Terrain: sort of flat, slight hills
Avg HR: 141
Avg speed: 15 mph +/-
Cal burned: 750

About me: 33yo, 5'-7", 130 lbs.

To me, your calories seem very low for 4+ hrs of riding but what do I know?! I often wonder the accuracy of HRM anyway.

[callmej]

I don't have a garmin, but use a Sigma bike computer. Your numbers, both in terms of calories burned and avg heart rate seem low to me, but maybe my signma is giving me higher numbers than actual. I just returned from a 20 mile ride, monderately hilly (I don't know the elevation gain, but I was huffing and puffing up a couple of the hills) , avg speed 15 mph - my avg heart rate was 144 and calories used 1159. I'm impressed with the length of your rides and your avg speed over those distances

[Triskeliongirl]

I think both your HR and cal numbers are low, compared to what I get on a similar ride on a very basic polar HRM. I don't know much about the garmin units, but on the polar you need to be sure to wet the contacts on the strap, so maybe you need to review that you put the HRM on correctly.

[Glory]

I don't know anything about the Garmin Edge but those numbers seem awfully low. I use a body bugg and granted I weigh a bit more than you but I burn roughly 500 calories on an hour ride and a much slower ride at that.

[nscrbug]

I think both your HR and cal numbers are low, compared to what I get on a similar ride on a very basic polar HRM. I don't know much about the garmin units, but on the polar you need to be sure to wet the contacts on the strap, so maybe you need to review that you put the HRM on correctly.

Yes, I do make sure to wet the contact points on the strap...and I also make sure that the strap is put on correctly - the GARMIN logo on the HR sensor facing right-side up...which it always does. I'm not sure what else I could possibly be doing wrong to get such low HR and calorie numbers...it's perplexing to say the least.

But I do feel a bit better knowing that you have all confirmed my beliefs of the low numbers. I'd be interested to hear if any other Garmin users are having similar experiences.

Linda

[azfiddle]

I use a Garmin 305. I rode 20.5 miles today, about 1 hour 22 min, and I burned about 800 calories. When rode 73 miles 2 weeks ago, 4 hrs 23 min, it said I used almost 3000 calories. Even if you're in great shape, you must be burning 500 calories an hour or more....

I can ask my DH who is the Garmin wizard around here. Did you set it up for your gender, weight etc?

[OakLeaf]

When the battery in my HR strap is getting low, it'll read low. I need to replace mine right now, actually ... about halfway through this morning's run the readout dropped by about 70 bpm.

I think setting your HR zones correctly has a lot to do with the accuracy of the calorie reading as well, but I have no idea how to do that manually. The old Garmins (like my 301) had an algorithm that would figure zones for running. I suppose they must not have been that accurate, or they would've brought that feature forward into the newer models, but it really seemed to track my perceived exertion well. I just carried those zones over into later versions of GTC, and into the cycling side, even though I know that MHR for cycling is lower than running.


ETA - to AZfiddle, the 305 doesn't use the HR based calorie computations. For running it doesn't make that much of a difference, but for cycling it's huge. Three hundred calories per hour is probably ballpark for most women cycling at average effort. Five hundred maybe if you're solo, in a headwind, or on the ascending side of a mountain...

[Mr. Bloom]

My Garmin is closely in line with normal Calorie burn charts...it registers more with speed and climbing.

I plan on 60-70 calories per mile

[nscrbug]

I use a Garmin 305. I rode 20.5 miles today, about 1 hour 22 min, and I burned about 800 calories. When rode 73 miles 2 weeks ago, 4 hrs 23 min, it said I used almost 3000 calories. Even if you're in great shape, you must be burning 500 calories an hour or more....

I can ask my DH who is the Garmin wizard around here. Did you set it up for your gender, weight etc?

Yup, I sure did. It was fairly self-explanatory, so I don't think that I screwed anything up in doing so. That would be great if you could ask your DH...I can use any help I can get in sorting this issue out. Thanks!!

Linda

[emily_in_nc]

Linda, have you tried taking your pulse manually while wearing the Garmin to see if the numbers are close? For example, stopping at the top of a hill when you feel that your heart is pounding or beating fast and taking your pulse at your wrist or neck while the Garmin is also taking it? You could try this at rest too. It's a simple test but may point out a discrepancy.

When I used to wear a Polar HRM, my max HR was usually around 180 or 190 and average HR around 150+ on a ride, and my calories burned about 400 per hour, and I'm little (<105 lbs). My DH, who weighs in the 150s, always burned a lot more calories than me on the same ride, according to his Polar, even tho his average HR was quite a bit lower than mine.

I agree with others, your numbers seem very low, though the calorie number is low b/c of the HR being low, so that's why I suggested verifying the unit is measuring your HR correctly. If it is, then you are very, very fit!

[OakLeaf]

Comparing your stopwatch pulse is a really good idea.

Do you have the new "premium" soft strap? Those are notorious ...

[nscrbug]

Comparing your stopwatch pulse is a really good idea.

Do you have the new "premium" soft strap? Those are notorious ...

Yes..it is the premium soft strap...which means what exactly? Are these straps known to cause inaccurate readings?

[OakLeaf]

Yes..it is the premium soft strap...which means what exactly? Are these straps known to cause inaccurate readings?

Yep. Known to lose contact if you're too wet, too dry, wearing the wrong kind of fabric ... I've got the old hard strap so I don't really know the ins and outs and whether there's much you can do short of replacing it, but take a look at the Garmin user forums.