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My girlfriend and I went for a walk on Sun. We climbed 3 peaks in Snowdonia. My girlfriend had one of them Nike tracking apps running on her phone all the while. In the end it gave us these stats:

Distance: 20Km (as the crow flies)
Time: 8 hours
Calories: 4000

The calories though were based on us walking on the flat. It didn't allow for the fact that we'd climbed over 1000m multiple times.

So how many calories did we realistically burn in the period of time we were walking? or is there a better way to work this out?

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    Just to be clear about the measurement method: does the app you're talking about rely on GPS, acceleration sensors to count steps, or both? – Benedikt Bauer Sep 11 '14 at 13:53
  • GPS @BenediktBauer. – user2766 Sep 11 '14 at 14:06
  • calorie tracking apps are notoriously bad at counting calories – njzk2 Aug 18 '17 at 5:50
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+150

Those values seem to be over-exaggerated. I was once measured by the professional equipment (from the local university) and my callory usage was 5000-6000 kcal a day, with average 20 km hike and 1000 meters elevation. This included the normal metabolism per day (about 2000-2500 kcal) + increased metabolism because of cold temperatures in night. The measures was based on blood pressure and skin temperature, from what I know it was the top-tech device for current state of knowledge.

So the hike 20km + 1000 meters elevation would make about 2500-3000 extra callories for male about 65 kg, with heavy backpack. Those are the extra callories burned, the basic metabolism is not included.

The app may include estimated base metabolism, but the distance made is not enough data to estimate that value. That strongly varies between individuals. Therefore to realisticly measure your metabolism, you need to measure pulse and body temperature.

  • define "heavy" for a backback – njzk2 Aug 18 '17 at 5:51
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An adult person burns between 100 to 150 kcal additionally per 100m elevation gained. Moreover, if you carried some common back bag you should add around 50 to 100 calories per hour. If the bag was very heavy you should add around 200 calories per hour.

Of course, these are only average values - for a more exact calculation we would need the weight, age of the persons as well as the weight of a possible back bag. (Source, unfortunately in German:)

  • Is there any increase for calories burnt when the elevation is taken into account though? – Aravona Aug 26 '14 at 13:54
  • Do you have a better URL for that info? The SE system doesn't like that one? (hence I guess why you had to format it as code?) – user2766 Aug 26 '14 at 14:16
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    unfortunately the better URL does not work on the target site: treibel-bergmed.de/bergmed/bergmed.php?section=7 – Jon Aug 26 '14 at 14:21
  • An adult person burns between 100 to 150 kcal additionally per 100m elevation gained. I tried estimating this using the results of the paper by Minetti (see my answer), and I got more like 50 kcal per 100 m. I calculated it for an 11.4 km hike with a 12% grade, finding the change when I changed the total climbing by 100 meters. Minetti's figures may be low for a couple of reasons, as discussed in my answer. – Ben Crowell Jan 12 '17 at 0:26
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There are so many things to consider when you calculate one such thing, and it would again involve a lot of data, equations and that too with subtle variations in data. For an example, there are people walking at different speeds, there would be differences, especially between walking and running.

You know, with trekking/hiking, its practically hard to draw a line between walking-like pace and almost-running-like a pace, and to add to mathematical complexity, there is another brisk walking kind of thing, that too considered along with Physiological data of the person? Like Height, weight, etc? So, the Highly accurate estimations are specific to the individual.

To consider those details for getting approximate measure of Calories burnt during a hike, a detailed bio-mechanical study of walking (and running) on steep gradient would be required for an appropriate characterization of the gait and for a clear identification, from the measure of contact times, of the transition from a walking-like to a running-like gait when the differences between walking and running tend to disappear. There has been a long debate over if the Speed really has anything to do with Work done, but I personally feel that, speed does play a (minor) factor in changing mechanical efficiency of human movement, may be a runner can tell better.

It could have been better if one consider the analytical data about Level Walking and Level Running and, how and why the difference between the Work done in both the case is subtle.

Speaking of gradients, When walking or running on positive gradients (ascends), both increases as the function of the incline (Elevation). So we can actually get away with obtaining the closer approximations if we consider walking, based on the fact that the approximation of considering just the mechanical potential work (and disregarding the kinetic one) because it is assumed that beyond a given gradient the rise (or descent) of the center of mass (consider, the load that you carried?) is the prevailing contributor to the mechanical external work.

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There is a paper here by Minetti et al. describing systematic measurements of this kind of thing:

To get an estimate, I assumed that you climbed up and down 1000 m twice, so that the gradient was 0.2. I don't know what your body weights are, so I used 66 kg. The result of the estimate is that you burned 1240 calories climbing and 170 calories descending, for a total of about 1400 cal. The estimate is extremely sensitive to the slope. For instance, if I reduce the slope to 0.15, it reduces the result by 250 cal.

This doesn't take into account the packs you were carrying. There's an app here from Hiking Science that tries to do that.

Minetti's numbers seem low by about a factor of 2 compared to other estimates I've seen. There may be a couple of reasons for this. Their subjects were "elite athletes practicing endurance mountain racing," so they may have been very efficient compared to most people. Also, they weren't carrying packs.

I've written some open-source software that can make this kind of estimate based on a GPS track:

It didn't allow for the fact that we'd climbed over 1000m multiple times.

Are you sure that it didn't? You say it used GPS, so it would have known how much you climbed and descended. If it really didn't even try to take climbing into account, then its estimate is even more silly. 20 km on the flats would be about 800 calories according to the estimates in the Minetti paper.

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