Calories: Strava or Garmin

Micilin Muc

I use a Garmin Forerunner 305 watch on Cycling mode to record all my rides. There are consistent discrepancies between what Garmin report and what Strava report my calorie burn is.

For example: 25.4km at 28.5km/h average.

Garmin (watch and Garmin Connect): 937 calories
Strava (using the same GPX file): 511 calories

Which is correct? Can I have that extra muffin every day? :rolleyes:

07Lapierre

I'd say there both wrong.. (eat the muffin anyway )

Inquitus

Micilin Muc wrote: »

I use a Garmin Forerunner 305 watch on Cycling mode to record all my rides. There are consistent discrepancies between what Garmin report and what Strava report my calorie burn is.

For example: 25.4km at 28.5km/h average.

Garmin (watch and Garmin Connect): 937 calories
Strava (using the same GPX file): 511 calories

Which is correct? Can I have that extra muffin every day? :rolleyes:

The lower number is generally the more correct number (unfortunately)!

wirelessdude01

Whatever it tells me I always divide it by teo as I feel that is a more representative number of what was burned.

petethedrummer

Both wrong. Both meaningless.

And anyone who tries to quote the laws of thermodynamics doesn't know the first thing about thermodynamics.

ashleey

Do you use a Heart Rate Monitor? It's more accurate with but is still an estimate based on average calorie burn based on weight and heart rate above resting rate.

Micilin Muc

ashleey wrote: »

Do you use a Heart Rate Monitor? It's more accurate with but is still an estimate based on average calorie burn based on weight and heart rate above resting rate.

Yes, and the watch has my date of birth and weight.

I know neither will be accurate, but all I want is a general idea. It's a big difference between 511 and 937, even more so when doing a longer ride.

ashleey

I think a good rule of thumb is 500 calories per hour for a 'proper' cycle on the bike, as in not too much rolling around, and so fairly constant pedalling force. I may be corrected though!

seamus

With calorie estimation, you're best off taking the lower estimation and then reducing it again by 25%.

Calorie estimation is like power estimation, but even more complicated.

The best rule of thumb which works for me is that one hour of riding at the highest intensity you can manage to sustain for an hour, will burn 1,000 kcal. This is "Holy **** I'm gonna puke, I'm going to get off this bike and lie down on that pile of broken glass because it's the only place available".

Time is a better measure than speed or distance, because a 1 hour climb might only cover 12km, but you'll be way more fncked than a 30km cycle on the flat.

So use that as your yardstick for calorie estimation. If your work roundtrip is 25km, and you're telling yourself that you can have a pizza & chips for lunch because you burned 800kcal today, well then you're gonna get fat. Chances are an hour at "normal" intensity (sweating, etc) is 500kcal, at most.

If you're measuring calories for the purpose of weight loss, then the best advice I can give is to not. A statistical curio, but don't "bank" calories burned through exercise, just eat normally. Unless you've done something big, 100km+, then you can undo everything with just one sneaky cream cake.

ashleey

Just to say that I think your Garmin uses an algorithm based on your heart rate stats and age and weight. Strava just throws up an estimate based on speed and time. I think?

petethedrummer

seamus wrote: »

Calorie estimation is like power estimation, but even more complicated.

no no. It's really rather simple. I worked it out here.
http://www.boards.ie/vbulletin/showthread.php?t=2057077294

Scrappy600

ashleey wrote: »

Just to say that I think your Garmin uses an algorithm based on your heart rate stats and age and weight. Strava just throws up an estimate based on speed and time. I think?

strava also takes the weight of the bike used into account as ive had my calorie count reduce when i set it as my mtb used by mistake and switched to the lighter road bike.

macnab

I have the same setup as the OP, I usually divide the Garmin figure by 2. Otherwise I allow 600kcal per hour.

Alek

Depending on intensity, I calculate 500 - 900 kcal per hour of exercise for my own food binging purposes. It seems to be working, as my weight hasn't changed over Christmas ;-)

(500 for cycling@25kmh, 900 for running as fast as I can sustain)

Big Eejit

I read on some forum, that you can half it for the Garmin, more or less (Also, the Edge 705 apparently doesn't take HR into consideration at all in it's calculation - and that's what I see - but newer models apparently do). From the same forum: Mr Average riding at reasonable pace, with reasonable exertion (I forget the figures) should be burn somewhere around the 400 mark. That's about half what my Garmin says I burn at the end of an hour's ride over the hills (but not too far away).

I don't have a link to the original source. Could've read it anywhere (even on boards.ie!)

on_the_nickel

The pertinent issue in the OP is what kind of muffin is it?

NeedMoreGears

Rounds Numbers

28.5kph - typical 160Watts (flat no-wind .....) - http://www.analyticcycling.com
25.4 km = 3208 seconds
Energy produced- 513,347 Joules
Typical human energy production efficiency - 24% (cant remember where from but really good cyclists 28%)
Energy Consumed = 2,138,947 Joules

4.182 Joules/cal

511 kcal (kcal are commonly called calories) - i.e 20kcal per km or so. Which by a total fluke is the Strava number

Alek

What is the weight of the cyclist + bike in this calculation?

NeedMoreGears

80kg rider
10kg bike

70watts for rolling resistence (rough Irish road) and 90watts for air (sea level, reasonably aero position, adult)

There are a plenty of variables to fool around with so I wouldn't place too much faith in the accuracy