Is there a significant difference between experienced and inexperienced runners of the same weight in calories needed to run a mile?
In: Biology
Yes, as you train your body adapts to the training, most relevant your cardiovascular system improves to pump blood for less energy. your heart will grow larger and you will develop more capillaries in your muscles that help diffuse O2. This makes your heart more calorie efficient, it is now capable of delivering more oxygen per beat.
I study exercise physiology, but I would not consider myself an expert yet. There is more to it such as transition of type 2a fibers to type 1, and increased mitochondrial count in these muscles, but I think most relevantly would be the cardiovascular changes.
All things being equal, the trained runner burns fewer calories, but the difference is pretty small. That runner will go faster and be able to sustain it longer, but calories/mile doesn’t change much, even between walking and running.
To start, a calorie is a measure of energy.
In the world of physics, the work (or energy) needed to move runner 1 (experienced) and runner 2 (inexperienced) a certain HORIZONTAL distance, is the same.
Work (W) = force (F) x distance (D)
Runner 1 will require the same force to move say one mile as runner 2 does because their masses are the same. Therefore the work that they each exert over a mile should also be the same. If a calorie is a measure of energy, and work is a measure of energy exerted, then the amount of calories needed to move runner 1 and runner 2 should theoretically be the same.
Power (P) = Work (W)/Time (t)
If Runner 1 is in better shape, then they can probably run that mile faster. So if they run that mile in half the time that Runner 2 does, then they have twice as much Power, I.e. P of R1 = 2x P of R2. And so Runner 1 would burn more calories over 10 minutes than Runner 2 if both are using their max power.
However, if the above was true, then there should also be no difference between Runner 1 walking a mile versus running that mile, and same for Runner 2. What the above does not account for is the biomechanics of running, i.e. you are also doing VERTICAL absolute work, more so when running than walking for example. In other words, when you’re running, your center of gravity moves up and down, and moving your center of gravity up will take work from your body, moving your center of gravity back down will take work from the earth.
Biologically, the difference between calories burned in one mile, as described by others who have posted, likely comes from the efficiency of the biomechanics of the trained runner versus untrained runner.
I could go into it, but this video would probably give you an idea of what I mean.
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