Running economy of African and Caucasian distance runners

Purpose: Anecdotal evidence suggests an advantageous physiological endowment of the African endurance athlete. Higher fractional utilization of (V)over dotO(2max) has been suggested but not measured directly, and investigations of running economy have been inconclusive. The aim of the current study was to measure a) running economy and b) fractional utilization of (V)over dotO(2max), in African and Caucasian 10-km runners of similar body mass. Methods: Eight African and eight Caucasian runners had no significant difference in mean race time (32.8 +/- 2.8, 32.0 +/- 2.5 min, respectively), body mass (61.4 +/- 7.0, 64.9 +/- 3.0 kg), age, body fat, or Iran thigh volume. Caucasian runners were 6 cm taller (P < 0.05). Subjects completed a progressive treadmill (V)over dotO(2peak) test. On a separate day, subjects completed two 6-min workloads (16.1 km . h(-1). and 10-km race pace) separated by 5 min. Results: Mean (V)over dotO(2peak) was 13% lower in the Africans (61.9 +/- 6.9, 69.9 +/- 5.4 mL . h(-1). min(-1,) P = 0.01). At 16.1 km . h(-1), the Africans were 5% more economical (47.3 +/- 3.2, 49.9 +/- 2.4 mL . kg(-1). min(-1), P < 0.05). This difference increased to 8% (P < 0.01) when standardized per kg(0.66). At race pace, the Africans utilized a higher %(V)over dotO(2peak) (92.2 +/- 3.7, 86.0 +/- 4.8%. P < 0.01) and had higher HR (185 +/- 9, 174 +/- 11 b . min(-1), P < 0.05) and plasma [ammonia] (113.2 +/- 51, 60.3 +/- 16.9 mu mol . L-1, P < 0.05). Despite the higher relative workload, the plasma [lactate] was not different (5.2 +/- 2.0, 4.2 +/- 1.7 mmol . L-1, NS). Conclusions: This study indicates greater running economy and higher fractional utilization of (V)over dotO(2peak) in African distance runners, Although not elucidating the origin of these differences, the findings may partially explain the success of African runners at the elite level.