Prodigious African Runners
17 Jul 2016
The dominance of African athletes in middle to long distance running, from the 1500m to the marathon, has attracted the attention of researchers on the possible reasons of this hegemony.
Leaving aside the social and economic reasons that surely play an important role, the first difference found in comparison with Caucasian runners is the "DISTAL WEIGHT", i.e. the calf-ankle mass which for the highlands runners is lower by about 400-500g than for their white colleagues.
Numerous studies have shown that every 50g of weight on the ankles increases energy expenditure by 1%. Therefore African runners would have a lower energy cost per kilometer of 8-10% compared to Caucasians.
Recent research though (Eur J Applied Physiol, 2012; 112: 3797-3806) has not shown significant differences in running efficiency between European runners able to perform a 2h08' marathon and Kenyan runners of equal fitness, suggesting that the African dominance depends on other factors.
The physical conformation with very long slender arms and legs favors HEAT DISPERSION, prolonging stamina and endurance: as a matter of fact, 75% of the energy produced is transformed into heat that must be dispersed effectively and profitably in order to limit the increase in body temperature during exercise.
Even in cycling, in the summer heat on the climbs of the TdF, tall and lean athletes with long thin limbs are favored in dispersing heat compared to cyclists with a more compact physique.
The majority of African long distance runners was born, lives and trains at ALTITUDE.
Kenyans are used to live above 2000m above sea level, and they train even higher.
European and Andean people respond to hypoxia by increasing the mass of hemoglobin (Hbmass) and the saturation of Hb (Hbsat).
Tibetans, while living at very high altitude, have a normal Hb instead: in fact they possess a variation of the gene EPAS1 that prevents the development of polyglobulia, with the relative blood viscosity problems.
Paradoxically they also have a low Hbsat, i.e. their hemoglobin carries "low" oxygen.
Tibetans live well at extreme altitudes thanks to an exceptional production of nitric oxide (NO), 200 times the usual level found in Caucasians.
NO drastically reduces pulmonary vascular resistance, increasing the flow of blood and alveolar gas exchange and therefore respiratory efficiency.
The Ethiopian Amhara ethnic group, which for millennia resided above 3000m a.s.l., manifests normal Hb and Hbsat, comparable to residents at sea level.
The Amhara have in fact developed an extraordinary ability to diffuse oxygen from the alveolus to the blood.
Still in Ethiopia, the Oromo ethnic group (Kenenisa Bekele and the Dibaba sisters are among them) has rather high values of Hb and Hbsat instead.
The Oromo shepherds in fact migrated on the highlands only 500 years ago, too short a time to induce gene mutations similar to the Tibetans and the Amhara.
Oromos are instead exceptional "altitude responders", showing significantly greater increases in Hb even at altitudes of less than 1500m above sea level.
Obviously, there are always different individual responses inside the same ethnic group, just as well as among Caucasian athletes.
The response to altitude training is extremely individual, requiring a personalized program to suit each athlete.
Those subjects, also Caucasian, born at altitude and with childhood and adolescence spent at high elevations, tend to develop more extensive pulmonary alveolar surfaces than those born and living at sea level, thus having a greater aptitude for aerobic sports.
The recent numerous cases of DOPING with rEPO in Kenyan and Ethiopian athletes, along with serious corruption in the system of controls, diminished, at least in part, the mythical status of the athletes of the highlands, who still dominate long distance running nonetheless, at least until the Caucasian athletes find the right motivations again and adopt the best training protocols to counter them.
At the end of the day, there is a talent recruitment problem, which should be encouraged, even economically, and enabled to develop quality and skills.