# Is there such thing as “meters per calorie” for living organisms?

I'm interested in learning if there's some way of quantifying the organism's metabolic efficiency associated with movement.

It seems to me that some organisms would be more efficient than others at using energy. For mechanical systems, there are clear metrics of efficiency, for example "miles per gallon" or "liters per 100km". Is there a similar metric that converts calories into how far an organism can go?

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This isn't what I'd call metabolic efficiency. Metabolic efficiency would be calories per gram of some standard nutrient(s). When you're converting calories into movement, it's more a matter of mechanical efficiency. – octern Nov 10 '12 at 1:38

Halsey & White (2012) Comparative energetics of mammalian locomotion: Humans are not different. Journal of Human Evolution 63:718–722

This paper presents a comparison of the metabolic cost of walking and running in humans, Australopithecus and other mammals. They use a parameter NCOT (net cost of transport), whose units are ml O2 consumed m-1. The inverse of this parameter would be related to your metres per calorie.

The authors quote an NCOT of 12.77 ml O2 m-1 for a walking human. Using a value of 4 kcal g-1 for glucose, I calculate that this NCOT is equivalent to 14.6 m kcal-1.

Here I found an energy consumption value of 5.8 kcal min-1 (for a 73 kg man) walking at 6.4 km h-1, which translates to 18.5 m kcal-1.

Incidentally, according to the authors of the paper:

The predicted net cost of transport (NCOT, ml O2 m−1) of mammals is related to mass (M, kg) according to 0.54M0.70.

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