I find your posts to be a bit over-generalizing and lacking of supporting evidence.
Examining the physiques of West Africans versus East Africans makes the genetic explanation pretty obvious.
What's obvious and could you share it with the rest of us?
From the article shared below (http://www.fims.org/default.asp?pageID=782860264):
"In a study of the demographic characteristics of elite Ethiopian athletes, 38% of the elite marathon runners were from the region of Arsi, which accounts for less than 5% of the Ethiopian population 2. As shown in Figure 1, these findings were mirrored in Kenya, where 81% of the best Kenyan runners originated from the Rift Valley province, which accounts for less than a quarter of the Kenyan population 1. "
"These initial studies of elite Kenyan athletes by Saltin et al. 6;14 demonstrate that factors such as increased childhood physical activity and hard training are probably the major contributors to the superior performances of Kenyan runners"
"The concept of ‘black’ athletic superiority is based on a preconception that each race constitutes a genetically homogeneous group, with race defined simply by skin colour. This belief is contrary to the assertion that there is more genetic variation among Africans than between African and Eurasian populations 24."
"interesting that Ethiopia and Kenya do not share a similar genetic ancestry, as defined by mtDNA 22;43, but what they do share is a similar environment: moderate altitude and high levels of physical activity. Few other regions of the world have such high levels of childhood physical activity combined with such cultural/financial importance being placed on distance running. This information clearly implicates environmental factors as being more influential than genetic factors in the success of East African distance runners. In an economically deprived region such as East Africa, economic factors also provide an additional motivation, if not a necessity, to succeed in distance running. In summary, it is unjustified at present to regard the phenomenon of East African running success as genetically mediated; to justify doing so one must identify the genes that are important. To do so also disregards the intense training regimens for which East African athletes are famous 56."
conclusion: not based on color of skin, nor based on genetics.