Running economy of African and Caucasian distance runners

Purpose: Anecdotal evidence suggests an advantageous physiological endowmen t of the African endurance athlete. Higher fractional utilization of (V)ove r dotO(2max) has been suggested but not measured directly, and investigatio ns 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. Me thods: Eight African and eight Caucasian runners had no significant differe nce 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 progres sive treadmill (V)over dotO(2peak) test. On a separate day, subjects comple ted 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 st andardized per kg(0.66). At race pace, the Africans utilized a higher %(V)o ver 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 wo rkload, the plasma [lactate] was not different (5.2 +/- 2.0, 4.2 +/- 1.7 mm ol . L-1, NS). Conclusions: This study indicates greater running economy an d higher fractional utilization of (V)over dotO(2peak) in African distance runners, Although not elucidating the origin of these differences, the find ings may partially explain the success of African runners at the elite leve l.