The fact that the African athletes could compete at a better running economy than the Caucasians at a higher intensity, with about the same amount of lactate accumulation, "suggests the lactate removal may be enhanced in African runners," write Weston and colleagues.
According to Martin, this study is likely an outgrowth of a past study showing that the lactate threshold seemed to be higher among African runners than Scandinavian runners.
"What this study is saying is, it may be that distance runners in Africa may be better than distance runners in other countries because they can race at a faster pace. And, obviously, the person who races at the fastest pace is the person who wins," Martin says.
So, "how come all these hundreds of Kenyans are racing at a faster pace than everyone else?" Martin asks. Is it the loaded issue of genetics, or the more likely answer: training?
In that same study of Scandinavian runners, a muscle biopsy was done of all the athletes, and no genetic difference was found, leading the researcher to propose a training-related phenomenon, says Martin. "The Kenyans tend to train at a higher, or faster pace," he explains.
Most runners tend to train below race pace, says Martin, whereas the Africans run at the higher pace at all times. "If you train at that pace, you'll adapt to that pace," he says, and use less oxygen while resisting lactic acid.
The Kenyans are known for training among hills and high altitude. Although both these things are present in other areas of the world, too, Martin points out that Kenya does have "long hills." He says, "It's a combination of many factors."
Also, Martin says, many Kenyan kids grow up running to school in bare feet, which also tends to build long-term injury protection because of lower limb flexibility. It's a process that can build the ultimate runner.
"These athletes are running machines by the time they start thinking about serious running," Martin says. By that point, they're more resistant to lactic acid accumulation, more resistant to fatigue. "It's like having a fourth gear instead of third gear," he says. "They've got overdrive."
"Whether they lift weights, run hills, or whether they run from childhood, I would think those would be the three likely contributors to running economy," Martin tells WebMD. "It's not all that complicated. These athletes are a product of their environment, just as our American athletes are a product of their environment."