Calories Strava vs My FitnessPal Vs Gamrin Connect

Triathlon Forum
1

I know that this is a very grey area, but wanted to throw it out there.

Last night I did a 2 hour TrainerRoad ride (Gibbs) http://www.trainerroad.com/cycling/rides/554338-Gibbs

1181 calories per Strava via the TrainerRoad file
1519 calories per MyFitness Pal via the Cycling 23-26 kilometres per hour entry
1058 Calories per Garmin Connect uploaded from my Garmin EDGE 810

So, which might be the accurate or most accurate one? It would seem somewhere in the 1050 -1100 range? I would have thought that this ride would burn more than 500 calories/hour?
So then, all calculations done in MFP are wrong?

2

My fitness pal is really not geared towards athletes but more the sedentry type who are trying to lose weight. On mine it says riding at 20mph for an hour (not that hard) burns 850+ calories so I guess is assuming that youre an unfit person for whom that would be an all out effort.

Garmin and strava are probably the most accurate but again that does sound a bit low… Have you got the setting right?

3

I know that this is a very grey area, but wanted to throw it out there.

Last night I did a 2 hour TrainerRoad ride (Gibbs) http://www.trainerroad.com/...g/rides/554338-Gibbs

1181 calories per Strava via the TrainerRoad file
1519 calories per MyFitness Pal via the Cycling 23-26 kilometres per hour entry
1058 Calories per Garmin Connect uploaded from my Garmin EDGE 810

So, which might be the accurate or most accurate one? It would seem somewhere in the 1050 -1100 range? I would have thought that this ride would burn more than 500 calories/hour?
So then, all calculations done in MFP are wrong?

I’d guess the 1500 cal for a 2-hr ride to be the closest, as 750 cal/hr seems like a reasonable estimate of cals burned in a moderately paced bike workout.

4

TrainerRoad/Strava/Garmin are about accurate. 500cal an hour for an easy ride is about right.

5

Today was a harder ride, 2:40 for 1954 calories. I think the 700/calories hour approx. seems accurate.

http://www.strava.com/activities/101497266

6

1500 is way too high for that for me.

Running 15 miles burns about 1500 calories. A 2 hour bike ride isn’t the same effort.

My powermeter reckons around 500 calories per hour on the bike. Unless you weight lots I guess ?

7

assuming his AP was ~ same as NP then ~3.6(kJ/w)x149(w)x2(hr)x(~4kJ/kCalx25%efficiency)=1070ish

most of my indoor trainer sessions run 900-1200 kJ/hr depending on length(1-4hrs).

8

Here is the math I’ve figured out, if I’m doing it wrong, please someone point out my error.

With a PM:

watts x duration of ride (in seconds) = joules. divide by 1000 to get KJ.

your KJ score *.24 = calories (technically kCal) burned.

So, 1000 KJ = 240 calories burned.

By my calculations, 277w for 60 minutes = ends you up at 240 calories burned.

This all seems much lower then we thought, though, right?

9

Myfitnesspal will always be wrong for our demographic. Often by a lot. It over-estimates my running calories by at least 20%. However, after you type in the time number, you can over-write the calorie burn in MFP.

DC Rainmaker wrote a breakdown of the different calorie calculations, and long story short, a newer Garmin with a HRM is going to be about 90% accurate. Add in a powermeter and it’s probably going to be closer than that.

10

Maybe I’m missing something, but wouldn’t the TrainerRoad work number of1062 be awfullyclose to accurate since the mathematical fluke of human efficiency (somewhat described here http://cyclingillustrated.com/tag/sean-burke/) makes the work number roughly equivalent to the energy burn?

11

Your calculation is missing engine efficiency. No one is 100% efficient, and most of us are less than 50%, so your calculation matches the 500 an hour guess that someone else made.

Otherwise your math is correct.

12

avg watts x 3.6kJ/watt = kJ/hr
it a kcal takes about 4 kJ, and humans are about 22-28% efficient more or less, so essentially it is really close to just take kJ=kcal

277ap for an hour=997 kJ= 977 kcal

edit…there are a ton of posts on this topic
.

13

assuming his AP was ~ same as NP then ~3.6(kJ/w)x149(w)x2(hr)x(~4kJ/kCalx25%efficiency)=1070ish

most of my indoor trainer sessions run 900-1200 kJ/hr depending on length(1-4hrs).

Do these numbers already take into acct the 25% efficiency, i.e. are the 900-1200 in essence cal/hr???

14

yes
.

15

yes

Ah, good, that’s what I thought, and similarly I’ve always figured I was burning 800 to 1100 cal/hr on the bike. If I ate based on 500 cal/hr, I’d starve to death:)

16

Thanks for pointing that out, folks. I hadn’t checked the forum here, only googled some conversion tables and such, but they didn’t mention anything about that.

So, cool, kJ = kCal. I can so that.