We have an arch in our foot that acts like a spring, short toes that are better for pushing off than for grasping tree limbs, and when we run, we can turn our torso and our shoulders like this while keeping our heads straight.
Imamo luk u stopalu koji  se ponaša kao opruga, kratki nožni prsti, bolji za odgurivanje nego za hvatanje grana, i kada trčimo, možemo okrenuti torzo i naša ramena ovako, dok nam je glava ravno.