Calories burnt and apps accuracy...??

[Turfy]

I assume there are lots of calculations based on averages...

The below screenshot just seems a lot of calories for the effort made. Taking into account:

- I'm 115kgs
- it was an almost flat route along the river mostly; the rest on the roads
- I was on a mountain bike with knobbly tyres
- I'm 42 years old

All of the apps say about the same Kcals, +/- 10%.

How accurate do you guys with more experience think the apps are?

Is there an app that is regarded as "more accurate" than the others?

[BMWBen]

It's basically a made up number - you might as well make one up yourself

[Scabutz]

If you use a power meter its very accurately measuring work done in calories. However, that take into account different efficiencies in the human body. 100 calories of output may require more than 100 of input.

Using a HRM will give slightly better accuracy as it is measuring how hard you are working.

Using nothing but GPS is at best a rough guess.

1k calories for an hours ride is over estimating it a lot. I ride with a PM and that says im outputting about 600-700 cals an hour. Similar weight to yourself. I'd burn 1k an hour running

[Turfy]

Scabutz said:

If you use a power meter its very accurately measuring work done in calories. However, that take into account different efficiencies in the human body. 100 calories of output may require more than 100 of input.

Using a HRM will give slightly better accuracy as it is measuring how hard you are working.

Using nothing but GPS is at best a rough guess.

1k calories for an hours ride is over estimating it a lot. I ride with a PM and that says im outputting about 600-700 cals an hour. Similar weight to yourself. I'd burn 1k an hour running

Thank for the detailed response. The figure I researched and had in my head was about 800kcals, MAX.

So between 600 and 800 is more likely the real number?

[Solocle]

This was yesterday's ride for me, but I have a HRM. I think they might overestimate based on MTB. I always used to get silly power figures on mine, although I had slick tyres.

Edited by Solocle on Monday 12th August 16:28

[PistonBroker]

I ran an errand to the other side of town on my MTB on Saturday. It needs a tweak - I can't get onto the big front ring at the moment - so I'd have worked harder on my road bike.

Wearing my Mi Fit and having the app track me gave a result of 349 calories burned over 10.5km. Average heart rate was 112.

Looks like the only other one I've tracked before is the 2.6kms to work and that gave me 77 calories burned and the average heart rate was exactly the same. It reckons I was going 1.8kph faster on that one. Same knackered bike.

I must get round to tracking myself on the fully working roadie.

[GOATever]

British Cycling work on 23 Calories per mile, for an ‘average’ rider, riding at ‘average’ intensity. Unless your smashing stuff in the Alps or something, that’s a fair assumption IMO.

[millen]

This is the formula used by Wahoo:

HOW ARE CALORIES CALCULATED IN THE WAHOO FITNESS APP?
Calories in the Wahoo Fitness app are calculated using an algorithm.  The calculation is made once per second and is different for men and women:
Men
calorieBurnRate = abs(((0.6309 * newHeartrate) + (0.09036 * weightInPounds) + (0.2017 * userAge) - 55.0969) / 4.184)
Women
calorieBurnRate = abs(((0.4472 * newHeartrate) - (0.05741 * weightInPounds) + (0.074 * userAge) - 20.4022) / 4.184)

Additionally, when BPM goes below 65% of max heart rate, Basal Metabolic Rate (BMR) is used in lieu of the algorithm, calculated as follows:
Men
BMR = 66 + (13.7 * weightKg) + (5 * heightCm) - (6.8 * ageYears)
Women
BMR = 655 + (9.6 * weightKg) + (1.8 * heightCm) - (4.7 * ageYears)


I used to think that Strava did it's own thing, eg reflecting elevation gain, but now it simply imports my Wahoo figure. Which for me is hugely overstated as my HRM is way higher than average. I'm not sure if Weight is supposed to be bare rider or rider + bike.

fwiw, the formula seems to set me at ~ 850 cals/hr for a reasonably hard ride, which is 2.3x the British Cycling estimate!

I do import Strava's avg power into my own rides spreadsheet. It's a good guide to relative hardness of the ride, but in absolute terms is rubbish.

One day I might have a powermeter........ it's been on order for 15 months now.

[Turfy]

GOATever said:

British Cycling work on 23 Calories per mile, for an ‘average’ rider, riding at ‘average’ intensity. Unless your smashing stuff in the Alps or something, that’s a fair assumption IMO.

So this for c.13 miles would be c.300kcals taking averages into account and on a "racer" style bike.

What is average intensity and average weight? I'm guessing about 11st - 13st?

[Turfy]

millen said:

fwiw, the formula seems to set me at ~ 850 cals/hr for a reasonably hard ride, which is 2.3x the British Cycling estimate!

If you don't mind me asking, what is your rough weight, age and average speed? I'm riding on a mountain bike on a flat towpath...

I don't have access to a heart rate monitor!

[millen]

Sure. I'm 64 y/o, 54 kg on a good day, and average 16 mph on a reasonably smooth solo road bike route (up to 500ft vertical per mile; hard to get much flatter where I live). But my heart rate is high - averages 140-149 on a tough ride, seldom averages below 131.

My ancient MTB is far harder work than the road bike. Much more rolling resistance, far heavier and clapped out drivetrain.

[Gruffy]

So many variables with this that the only accurate way to know your calorie burn for any given intensity is to hit the sports lab and do a test.

[Turfy]

millen said:

Sure. I'm 64 y/o, 54 kg on a good day, and average 16 mph on a reasonably smooth solo road bike route (up to 500ft vertical per mile; hard to get much flatter where I live). But my heart rate is high - averages 140-149 on a tough ride, seldom averages below 131.

My ancient MTB is far harder work than the road bike. Much more rolling resistance, far heavier and clapped out drivetrain.

So you're c.20% faster and under 50% my weight so it's not inconceivable I'm burning c.600kcal p/h on a mountain bike.... 1000kcals as on the app is hard to believe. especially at c.13mph

Of course, I'm essentially on the flat!

[GOATever]

Gruffy said:

So many variables with this that the only accurate way to know your calorie burn for any given intensity is to hit the sports lab and do a test.

Very true.

[GOATever]

Turfy said:

So this for c.13 miles would be c.300kcals taking averages into account and on a "racer" style bike.

What is average intensity and average weight? I'm guessing about 11st - 13st?

That sounds about right. Intensity would be based on weighted average power.

[BMWBen]

GOATever said:

Gruffy said:

So many variables with this that the only accurate way to know your calorie burn for any given intensity is to hit the sports lab and do a test.

Very true.

Or to get a power meter... Probably about the same cost, and will give you real time data forever!

[Coolbanana]

I use a Garmin Fenix 5 Plus watch with HRM. It is generally showing me as using circa 443 calories per hour mountain biking going by my last ride, average HR 122bpm, max 173bpm, 41km, 556m climbing, over 2 hours and it included taking 2 Strava KOM's so some effort in various stages.

I don't think that would be far off in terms of calories actually. I only see a lot of the stats as a 'guide' to how I'm doing and they are comparable to previous using the same measurements so I can see how my relative effort is etc and if I am improving.

[Yidwann]

For me on the turbo trainer, an hour of reasonable pace, 94kg, 36 and an average HR in that session of 150-160 would bring in about 700-800 calories. Measured with my garmin and a HRM Strap, so I'd like to think that's a fairly accurate picture.

[BMWBen]

Scabutz said:

If you use a power meter its very accurately measuring work done in calories. However, that take into account different efficiencies in the human body. 100 calories of output may require more than 100 of input.

Using a HRM will give slightly better accuracy as it is measuring how hard you are working.

Using nothing but GPS is at best a rough guess.

1k calories for an hours ride is over estimating it a lot. I ride with a PM and that says im outputting about 600-700 cals an hour. Similar weight to yourself. I'd burn 1k an hour running

I don't think you're quite right about this...

1. Power meters accurately measure work done (usually +/- 1-2%).

2. The energy efficiency of a human is effectively constant and is between 18-25%. 20% is the number which is often used for calculations.

3. If you aren't 20% efficient, then at least the numbers you get for calorie burn from a power meter will be consistent with each other. You could do a lab test to calculate your own efficiency and then correct based on that number.

4. Heart rate is only loosely coupled with how hard you're working. Some days your heart rate will be higher for the same rate of work, some days lower.

5. Heart rate is not consistent between different people. 220-age for max heart rate and then zones calculated from that is useless/inaccurate. The variance from person to person is huge. A heart rate of 165bpm for a person tells you absolutely nothing about the rate at which they're burning calories. There's a friend I ride with who has a higher heart rate than me, but I have higher power output. When he's doing a heart rate of 175, the same power output for me is about 155.

6. Because of the above 2 points, you cannot calculate work done or energy burned from heart rate rate with any kind of accuracy or consistency.

So in summary, HRM does not give you better accuracy for calories burned.

[lufbramatt]

Agree with previous post ^

Rough rule of thumb is 1KJ energy output (i.e. measured with power meter) is roughly equal to 1 Kcal energy input due to the human body not being very efficient

(1Kcal = 4.2 KJ)