Running economy and lower‐limb anthropometry in adult male Kenyan and Danish middle‐ and long‐distance runners and in untrained adolescents

Kenyan athletes have dominated competitive middle‐ and long‐distance running for more than half a century, a phenomenon suggested to be attributable, at least in part, to superior running economy. Given that lower‐leg anthropometry is an important determinant of running economy, a key contributor to the athletic performance of Kenyan runners is thought to be slender lower legs. Running economy and lower‐leg anthropometrics, including relative lower‐leg length and mean lower‐leg thickness, were measured in adult middle‐ to long‐distance runners, including 12 Kenyan elite and 29 sub‐elite runners, and 20 Danish elite and 37 sub‐elite runners. Additionally, 46 untrained Kenyan and 30 untrained Danish adolescents were included. Among adult runners, the oxygen cost of running was 33.61 mL kg −0.75 km −1 lower in Kenyans compared with Danes [95% confidence interval (CI): 18.63, 48.59; p < 0.0001] and increased by 2.20 mL kg −0.75 km −1 per centimetre squared increase in lower‐leg cross‐sectional area (95% CI: 1.03, 3.37; p = 0.0005). In untrained adolescents, the oxygen cost of running was 44.82 mL kg −0.75 km −1 lower (95% CI: 21.99, 67.64; p = 0.0002) and increased by 1.75 mL kg −0.75 km −1 per centimetre squared increase in lower‐leg cross‐sectional area (95% CI: 0.18, 3.32; p = 0.0294). Slender lower legs are favourably associated with superior running economy and might contribute to the dominance of Kenyan athletes in competitive middle‐ to long‐distance running.