odd then, isn't it, that the human body was adapted for running? let's list a few of those adaptations:
Brain: Hippocampus stimulation
running activates 33 genes in the brains center for mood, memory, and learning. also stimulates the formation of new brain cells and blood vessels.
Head: Flat face
humans lack the protruding snout of apes, so our heads are more balanced over our necks while in motion.
Neck: Nuchal ligament
this ligament helps stabilize your head and prevents it from pitching back and forth, a feature found only in mammals built for running, such as dogs.
Respiratory system: Mouth breathing
unlike the panting of many quadrupeds, human mouth breathing permits more airflow with les muscular effort, and helps repel heat.
Skin: sweat glands and less hair
we shed better than hairier mammals
Shoulders: low, broad shoulders
our wide shoulder span increases arm swinging, which counteracts the torque generated by our legs. otherwise our bodies would rotate and we'd be thrown off-balance. your head moves separately from your shoulders and trunk (ever see an ape do that?), so you can look forward as you run.
Ass: larger gluteus maximus muscle
extends the thigh to propel the body, keeps you from pitching over with forward momentum.
we look and function the way we do because our survival once depended on endurance running. when conditions are right, a man can run even the fastest antelope on earth to death by overheating, because we have sweat glands, and they don't. look up the Kalahari, their hunters were found to be doing just that in the early 1900s.