Humans are bipedal, and that means we are built to WALK! er, RUN! Speed is the supreme coefficient in athletic metrics, the ability to get from point A to point B. Period. It is definitive and irrefutable.
We may not be bio-genetically designed to run like cats- cheetahs!- or scamper like hares, darting in the brush, but we most definitely know how to giddy up- we can kick it into “top speed”. That places us [humans] in a preternatural class of extra-pedal navigation. We are an ULTIMATE hybrid: we can crawl four-legged, walk quite efficiently, swim not ineffectively, climb remarkably, and fly like a . . . okay, the flying is probably still on the back of the evolutionary learning curve, but it must be coming..(soon?).
Running not be the most productive of the essential eight movements, but it is definitely one of the most primary and more primitive actions known to man. You gotta run to catch your prey and you gotta run so you’re not preyed upon. Sounds a lot like, kill or be killed. So, I guess the age-old expression, “Running for your life”, presents a curious double meaning: not only running FROM that which means to kill or defeat you, but running FOR your health and your happiness, i.e. your prolonged experience here on this globe, viz. living into your sixties (and your seventies and your eighties) with a sufficient kick of youth still throbbing inside your coat pocket.
Grass Is Greener Fitness 