Running efficiency: stretching the truth

One of the most fundamental requirements for excellent running performance is an efficient running technique, where the amount of forward motion produced by the working muscles is maximized during submaximal workloads. More correctly known as ‘running economy’, runners with a high level of running economy can cover more ground at a given pace while using less oxygen per kilo of bodyweight than runners with poorer running economy. And since there’s a limit to the amount of oxygen that can be pumped around the body to working muscle before lactate accumulation starts to set in (producing fatigue and slowing the pace), runners with higher levels of economy will – all other things being equal – outperform runners with lower levels of economy.

Running economy is important

If muscle economy measures how efficiently muscles work at submaximal work rates (ie not flat out at maximum oxygen uptake), why is it important for maximising race performance? That’s because it turns out that a large body of evidence has found that elite athletes have much higher levels of muscle economy than their amateur or recreational counterparts. In other word – muscle economy and high levels of endurance go hand in hand. For example, a study of collegiate cross-country team members discovered that just two factors – maximum aerobic capacity (VO2max) and running economy - could account for 92% of the variance in performance during an 8000-metre race⁽¹⁾. Also, running economy, like VO2max, has successfully been used to estimate average marathon pace in elite runners⁽²⁾.

In another study, researchers were mystified as to why the performances of a group of elite Eritrean runners were consistently better than those of a group of elite Spanish runners, even though both groups had very similar maximum aerobic capacities⁽³⁾. Subsequent testing on both groups revealed that the key physiological difference was the exceptional running economy 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: Figure 2: Oxygen consumption (mls/kg/min) at 21kmh