What is running efficiency?

Efficiency is defined as the work done related to energy expended. Basically, when it comes to running, it’s a way to describe how much energy is required to run at a specific speed.

However, since running speed itself is not a direct measure of work or energy, exercise physiologists prefer to use the word “economy.” This is why you’ll see economy used predominantly in published research studies.

Running economy is defined as the energy demand for a given velocity of submaximal running. That is, how much oxygen your body needs to run at any given pace below your all-out racing stride.

Measuring this directly requires monitoring steady-state consumption of oxygen and the respiratory exchange ratio. Taking weight into consideration and assuming the same speed, runners with good economy naturally use less energy and oxygen than runners with poor economy.
In the end, this is an even stronger predictor of race performance than maximal oxygen uptake in elite runners with similar VO2max levels.7
Admittedly, this is a very complex matter to measure. That’s why economy is traditionally assessed by running on a treadmill in standard laboratory conditions. This is not the same as running outside or on a track, but it does provide a decent indication of how economical a runner is and how economy can change over time.8

We’re not in a lab right now, however. Nor are we on a treadmill. And chances are high that, if you’re reading this e-book right now, you’re not either. That means that, for practical purposes, we can use efficiency and economy interchangeably – even though they do have different technical definitions. Also for practical purposes, we’ll only be referencing efficiency going forward.

Why does this matter?

Unless you’ve stood atop an Olympic podium or broken tape at a major road race, your running efficiency is likely on par with most other runners. This means that only about 20% of the energy you expend while running is actually used to propel yourself forward. The other 80% is lost – wasted – as a result of heat produced by muscle contractions and energy loss from up/down motion you can’t recover for forward movement.1,2

The science behind running motion and efficiency is fascinating, but we’ll spare you the details for now and jump straight to the punchline: Recapturing even a portion of this lost energy while running can help you improve your time and distance capabilities and get more enjoyment every time you run.

Consider two runners with the same work capacity, or maximal oxygen consumption (also known as peak oxygen uptake or VO2 max). They can be the same age with the same healthy background, and train together every day for weeks leading up to any given race. Yet, on the big day itself, their race times can vary up to 20% due to differences in their efficiency.3,4

To look at it another way, this 20% efficiency variation is the difference between running a 3-hour and 3.5-hour marathon with the same fitness level!

For most runners, even a mere 5% efficiency increase translates to more than one minute’s difference over a 5K. So any improvements you can make in this area essentially equate to “free speed.” You’ll move faster at a given level of effort.

There are many strategies for improving efficiency that are easily realized through specific training, technique and gear-selection strategies (among other things). We cover these methods in-depth elsewhere in this site!

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