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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 at 13:53
    
GPS @BenediktBauer. –  Liam Sep 11 at 14:06

3 Answers 3

up vote 4 down vote accepted
+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.

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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: http://85.25.34.248/bergmed/bergmed.php?section=7)

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Is there any increase for calories burnt when the elevation is taken into account though? –  Aravona Aug 26 at 13:54
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should 100m hiking be 100m height gained? –  Liam Aug 26 at 13:55
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should 100m hiking be 100m height gained? => yes. –  Jon Aug 26 at 13:55
    
@Jon much clearer now +1, good info. –  Aravona Aug 26 at 13:59
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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 at 14:21

There a 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 he 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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