>>508411970east Africans for long distance, west for sprints.
africans have longer legs for their height and higher calves, think a weight on a broom. Whites lower calves are a mechanical disadvantage running, requires more effort to move, but puts more flesh around the ankle for warmth when trudging through snow. Whites are built to survive an ice age. Or the ice age thinned out Whites who weren't.
There is also bone length ratio difference but the mechanics is hard to describe. For leg length , whites have longer thighs. Also wider hips, making a less smooth gait but also helps maintain body heat