Last updated: 2026-06-30

Running Economy

Running economy describes how much oxygen a runner burns to travel at a given speed. Two runners with identical VO₂max values can race very differently if one consumes less oxygen at the same pace — that runner is more economical. Together with VO₂max and the lactate threshold, running economy is one of the main physiological factors that separate distance runners. This calculator turns a submaximal VO₂ measured at a steady pace into an oxygen cost per kilometre, so you can track efficiency over a training block.

The definition

Running economy is the rate of oxygen use divided by the running speed, which converts an oxygen flow (per minute) into an oxygen cost per unit distance:

Here $RE$ is running economy in ml O₂ per kg of body mass per kilometre, $\dot V_{O_2}$ is the measured oxygen uptake in ml/kg/min, and $v$ is the speed in km/h. The factor of 60 converts minutes to hours so the units cancel to ml/kg/km. Because the same VO₂ is being spread over more distance as speed rises, a higher speed at the same oxygen rate produces a lower — better — economy value.

Worked example

Suppose a runner records a steady VO₂ of 45 ml/kg/min while holding 12 km/h on a treadmill. The oxygen cost per kilometre is:

If a second runner needs only 40 ml/kg/min to hold the same 12 km/h, their economy is 200 ml/kg/km — they cover the same distance on less oxygen and would, all else equal, run faster or longer at the same effort.

Why lower is better

Unlike VO₂max, where a higher number is fitter, running economy improves as the number falls. A lower oxygen cost means less of the body's aerobic capacity is spent at any given pace, leaving more in reserve. Improvements typically come from training adaptations and from form and equipment: years of aerobic mileage, strength and plyometric work, lighter shoes, and a more efficient stride all tend to reduce the oxygen cost of running. Because economy is speed-specific and sensitive to surface and protocol, the most reliable read is your own trend: measure at a similar pace each time and watch whether the cost per kilometre drifts down.

Measuring it well

Running economy is measured in a lab with a metabolic cart, usually on a treadmill at a fixed submaximal pace held until oxygen uptake reaches a steady state. The VO₂ and the speed must come from that same steady effort, since pairing a VO₂ from one pace with a different speed gives a meaningless figure. Standardising conditions — warm-up, treadmill gradient, footwear, and time of day — makes repeat tests comparable. The estimate from this calculator is only as good as those inputs.

Putting it in context

A running-economy figure is most useful alongside other aerobic markers. To see the maximal end of your aerobic capacity, use the VO2 Max Calculator. To translate fitness into target paces for training, the Running Pace Calculator calculator helps, and the Grade-Adjusted Pace Calculator calculator is useful when hills make raw pace misleading. Tracked together over a season, these give a fuller picture than any single number.