Running shoe technology: the cost of carbon

One of the key performance indicators for distance running is something known as ‘running economy’^(1-3). Basically, running economy (which often abbreviated as RE) it refers to how efficiently the muscles are able to utilize oxygen delivered to them by the cardiovascular system in order to provide the energy required to generate forward motion during running (more technically defined as the steady-state oxygen uptake at submaximal running speeds). RE is considered important for performance because all other things being equal, a runner with high levels of RE is able to sustain higher exercise intensities and/or maintain the same exercise intensity for a longer period of time compared to a runner with poorer RE⁽⁴⁾.

RE matters

It’s difficult to overstate how important good levels of RE are for running performance. Indeed, a key difference between world class athletes and ‘merely’ elite athletes is that the former tend to have exceptionally high levels of RE despite maybe having lower absolute maximum levels of oxygen uptake. To illustrate this, research comparing Eritrean runners with elite Spanish runners showed that while both groups had very similar maximum aerobic capacities, the performances of the Eritrean runners were consistently better than those of the Spaniards⁽⁵⁾. This mystified the researchers, but further investigation revealed that the reason was the exceptional RE of the African runners; at 21kmh (13.0mph), the Eritreans needed to consume just 65.9mls of oxygen per kilo per kilometre - compared with 74.8mls of oxygen for the Spanish runners (see figure 1).

Figure 1: Oxygen consumption per kilo per kilometre at 21kmh