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I'm thinking of something like, say, a line diagram. The horizontal axis would be "running speed" and the vertical axis something like "calories per minute". Has this matter ever been scientifically researched?

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    Well.... I know guys who can run 6 minute miles and have a conversation like they’re walking. If I tried to run a 6 minute mile, I’d be gasping for air in about 30 seconds. The difference? Heart rate. Calorie burn is mostly dependent on heart rate and not speed. What’s fast for some isn’t fast for all. So, running a 6 minute mile for me would burn far more calories than a 6 minute mile for someone else. Heart rate increases to supply demand of oxygen from muscles that need them. The higher the demand the more calories – Frank Feb 4 '19 at 22:01
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    @Frank - Heart rate is not really a reliable gauge of calorie burn. There is an estimation because there is a somewhat linear relationship in steady state exercise between hr and vo2 uptake. But take the same person in two different workouts. One workout is at 90bpm running 10 minute miles, the next day they have extra coffee or fatigue, and the same 10 minute miles are now at 100 bpm. They are not burning an extra 10% calories. – JohnP Feb 4 '19 at 22:38
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    europepmc.org/abstract/med/870783 calories should be proportional to oxygen rate. it's a line. the gradient varies between individuals. – ColonelFazackerley Feb 5 '19 at 19:28
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It would look like this:

chart

It's basically a straight line. Don't take the variations from the straight line too seriously. There are so many other factors involved (wind, distance, running form, etc.) that it doesn't make sense to try to measure it too precisely. The graph above is for a 30 year-old male with 70 kg and 1.75 m, calculated with the corrected MET values taken from the Compendium of Physical Activities. You can make your own graph with your personal parameters with this spreadsheet.

It is well-known that you burn approximately the same calories per km independently of speed. A fortunate numerical coincidence allows us to simplify the formula and simply take the speed in km/h to get how many calories you burn per kg per hour. For example: a 100 kg person running at 12 km/h burns about 1200 kcal per hour and a 50 kg person running at 20 km/h burns about 1000 kcal/h.

  • the chart you provided doesn't effectively prove your final point, as it seems to show that you burn more calories the faster you run, when in your final paragraph you say you don't. the vertical axis in the chart should be calories per kilometer, not calories per minute. obviously you will burn more calories if you run fast for a minute versus running slow for a minute, since you've just covered more ground (and your body has done more work). – user3163495 Sep 10 '19 at 21:04
  • @user3163495 The OP asked for calories per minute, which is what the chart shows. And it's not meant to prove my final point. The spreadsheet I linked to shows the graph you're interested in. It's basically an horizontal line. If you want to learn how everything was calculated, read sites.google.com/site/compendiumofphysicalactivities/… or en.wikipedia.org/wiki/Metabolic_equivalent_of_task – Wood Sep 10 '19 at 21:10
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Short answer: the line on such a diagram would just be a straight horizontal line. Running faster does not significantly increase calories burned.

Long answer: A "calorie" in the context of food and exercise is actually short for "kilocalorie", which is a unit of energy (or "work", as some people say).

Just like 1 mile is equal to 5,280 feet, 1 kilocalorie is equal to 4,184 Joules, which is the same amount of energy/work required to raise the temperature of 1 kilogram of water by 1° Celsius.

Let's say you dragged a 100lbs boulder 20 feet across the ground. No matter how fast you dragged that boulder, it will always be the same amount of work done: 100lbs moved 20 feet.

So, based on how much you weigh, the amount of calories you burn running a mile will roughly be the same no matter how fast you run. I know it sounds counter-intuitive, since running fast is harder than running slow, but that's science.

You might burn a few more calories in the wind since wind resistance increases the faster you go, but it's not very significant unless you are absolutely sprinting.

That is the reason the calculator on this site will always give you the same number of calories burned, no matter how fast a time you put for the "How long you ran" box:

https://www.runnersworld.com/training/a20801301/calories-burned-running-calculator/

Caveat: calories burned while running will always be the same, but there might be some increased after-burn of calories if you ran the mile super fast as opposed to normal speed, since your body has to work harder to catch its breath, cool off, etc.

  • As far as I read it, you argue that distance matters, but speed does not! This also match an very old rule-of-thump: energy(in kcal) ~ your weight(in kg)*distance (in kg). – Tonny Madsen Feb 28 '19 at 9:48

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