Running Economy: How Efficient Are You?

Submitted by Rickshaw :: Tue Jan 18, 2005 10:37 am

When runners talk about economy, they don't mean all the money Nike makes. Running economy is a measure of how efficient a runner's body is at turning oxygen into forward motion, and is an often overlooked component of performance. To use an automotive analogy, many runners concentrate on speed gains stemming from increasing their engine's horsepower, but economy improvements are more akin to streamlining the body panels to cut drag. Both are effective methods of improving speed, but the first method tends to get most of the attention.

When running at race pace, your body is engaged in the business of converting oxygen into muscle energy and forward motion as rapidly is possible. The maximum rate at which the body can take in and burn oxygen is called VO2max, and is one of the primary limits of performance. There's significant variability in VO2max between people, and it can also be increased through training. Repeats of intervals at the track are the classic method used to boost VO2max.

VO2max is only part of the story, however. Two runners with the same VO2max value may perform very differently in a race, due to differences in economy. If runner 1 requires less oxygen to run at a particular pace than runner 2 does, then runner 1 will not need to work as hard to run that pace. Or alternatively, runner 1 can travel at a faster pace while maintaining the same relative effort level (rate of oxygen comsumption) as runner 2. It's the combination of VO2max and economy that matters: low VO2max and high economy will perform similarly to high VO2max and low economy on race day.

So how do you improve your running economy? The standard approach is various types of strength training targeted for economy improvements. Hill workouts, weight lighting, and core strength exercises all help to build and condition muscle. Those muscles will make a subtle but important contribution to keeping your running form clean and smooth, especially late in a race as you begin to tire. Any wasted body movements or excessive leaning will decrease your running economy, which is why strength is important. Short, fast intervals or "strides" have also been shown to help improve running form and increase running economy.

One intriguing finding for those who hate stretching is that increased flexibility is correlated with decreased running economy. This may seem to contradict common sense, but recent research studies have suggested that trunk and lower limb flexibility are inversely related to running economy. In one study, subjects who exhibited tightness and limited flexibility in the trunk were the most economical at every test speed. Researchers hypothesized that inflexibility reduced energy expenditure by enhancing elastic energy storage and return in the tendons and muscles.