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Delusional Calorie Counter

I know that calorie calculations with just a HR monitor is going to be inaccurate bordering fictional, but why even display this metric when estimates are off by a factor of 3 between calculators.
It's just as redundant as estimated power output without a power meter.

I went for a 1h30min trail ride the other day with about 230m of elevation climbed, spent about 30min in Z3 and 35min in Z4, and it was generally a comfortable ride. Garmin estimates a whopping 930 calories and Strava around 243 calories.

I'm going to guess its somewhere in the middle, but both feel very wrong.
Is there a way that I could calculate this to be somewhat correct within some acceptable margin of error considering I've only got a chest HRM.

Thanks.

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nghpmc over 5 years ago in reply to Martin +2 verified

http://large.stanford.edu/courses/2010/ph240/stetler1

The work is what the powermeter measures (1233 KJ) .In order to create this work one has to burn calories wich is dependent on your efficiency . So…

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0 nghpmc over 5 years ago

You could try this : http://www.calories-calculator.net/Calories_Burned_By_Heart_Rate.html I put in my HR data from a powermeter based ride and got 1532 calories from the tool, and based on my powermeter calculated calories was 1229 in Strava and 1393 in Garmin Connect . ( ride in question: https://www.strava.com/activities/3107717155 )

0 Martin over 5 years ago in reply to nghpmc

Thanks.

According to the linked page calculation, Garmin comes closest, but it still seems high.

Your values for Strava are not 1229 Calories. It's 1229 kj, which is something very different.

0 nghpmc over 5 years ago in reply to Martin

Well, take a closer look :-)

0 Martin over 5 years ago in reply to nghpmc

Thanks ‍

But how is 1229 Cal = 1233 kj?

Assuming Cal means kilocalorie

+1 nghpmc over 5 years ago in reply to Martin

http://large.stanford.edu/courses/2010/ph240/stetler1

The work is what the powermeter measures (1233 KJ) .In order to create this work one has to burn calories wich is dependent on your efficiency . So the calories are computed from the power data. The calorie joule conversion factor is around 4 so that brings the numbera for work and calories to almost the same figure, as the efficiency is around 0,20-0,25...

0 Martin over 5 years ago in reply to nghpmc

Cool, thanks for that!

0 mcalista over 5 years ago

You can expect to burn 6-10 calories per minute for moderate to vigorous exercise. Above 10 for very hard sustained efforts.

Strava sounds way too low for a 90 minute ride. Garmin sounds quite feasible.

And chest HRM's are generally reckoned to be more accurate than other HR measurement methods.

0 Martin over 5 years ago in reply to mcalista

Thanks. Yeah, I had some basic info that was missing and also made incorrect assumptions about Kj and Cal being the same thing wrt what it measured, but with NGHPMC's clarification it all makes sense. Noob error :)