How do you calculate the overall efficiency of a runner?

One of the factors determining how well an athlete realizes his or her aerobic potential in competitive conditions is so-called “overall efficiency.” Overall efficiency is calculated as the ratio of mechanical energy to the metabolic energy produced by the athlete's body.

A gas analyzer test under standardized conditions provides valuable physiological information, including calculating the overall efficiency coefficient.

Exhaled gas analysis and power measurements are needed to calculate overall efficiency. Some treadmills make power measurements – it’s important to enter your weight to arrive at an accurate measurement-- or you can use a running power sensor like Stryd:

Stryd running power sensor

To understand how to do the calculation, let's look at  the data of a fictitious athlete.

For this athlete, when running at 16.0 km/h, oxygen consumption is 3.055 l/min. The respiratory ratio (RER) is 1.0 (this is necessary to calculate the metabolic energy according to the tables of non-protein equivalents). The energy equivalent of oxygen consumption, in this case, RER, is 5.189 kcal/l. This is a standardized figure which you can obtain by….  Therefore, the kcal consumption per minute of running is calculated by multiplying 5.189 x 3.055 = 15.85.

Next, we convert from kcal into joules: 15.85 x 4.1868 \u003d = 66.37 kJ.

Running power (as measured by the power sensor) at this speed is 262 watts. To get an estimate in kilojoules, we must multiply by the duration and divide by 1000: 262 x 60 / 1000 = 15.72.

The final step is to calculate overall efficiency:

Overall efficiency = 15.72 / 66.37 x 100 = 23.7%.

For cyclists, the arsenal of efficiency calculations is more extensive and includes net and delta efficiency estimates. But we'll talk about this next time. Remember to share this article with your friends if you find it helpful!