Several East Africans are among the most successful runners worldwide. The physiological reasons underlying this superiority are, however, not yet known. Purpose: To evaluate the total hemoglobin mass (tHb-mass) and blood volume (BV) of Kenyan runners and their adaptation to near sea level. Methods: tHb-mass, BV, and VO2max were determined in 10 male Kenyan runners (10-km best time = 28:29 ± 00:27 min) residing at an altitude of 2090 m over the course of a 6-wk training camp at sea level. Their values were compared with those of elite German runners (10-km best time = 30:39 ± 00:24 min). Results: Kenyans are characterized by significantly lower body mass (Kenyans = 57.2 ± 7.0 kg; Germans = 66.5 ± 6.3 kg) and body mass index (Kenyans = 18.5 ± 0.9; Germans = 20.4 ± 0.9). Relative tHb-mass (Kenyans = 14.2 ± 1.0 g/kg; Germans = 14.0 ± 0.7 g/kg) and BV (Kenyans = 101.9 ± 4.5 mL/kg; Germans = 99.6 ± 5.8 mL·kg-1) were similar in both groups but were decreased in Kenyans during the stay at near sea level (absolute tHb-mass from 813 ± 90 g/mL to 767 ± 90 g, P < 0.001; BV from 5828 ± 703 g/mL to 5513 ± 708 mL, P < 0.01). Relative VO2max was similar in both groups (Kenyans 71.5 ± 5.0 mL/kg·min; Germans 70.7 ± 3.7 mL/kg·min). Conclusion: The oxygen transport of the blood cannot explain the superior endurance performance of Kenyan runners. Most measured parameters are in the same range as those of elite German runners, and tHb-mass even deteriorates after an adaptation to near sea level.
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