A recognised theory on why we are built to run is persistence hunting. Horses sweat, but most other quadrupeds don’t. The way they lose heat is by panting, and they can’t pant and run at the same time. So although they can run faster than humans, they can only do this for short periods. After which they have to stop to pant and cool down. A human running at a normal pace can sweat while they run, they don’t need to stop to regulate their temperature.
Therefore if a human continues to run after an antelope, the human will catch up with the animal before it’s had time to cool down. It’s forced to run again, and again, and again. Eventually the antelope will overheat and die. Time for dinner!
Persistence hunting is still practised today by hunter-gatherers in the central Kalahari Desert, Southern Africa. David Attenborough’s documentary The Life of Mammals, Food For Thought (ep 10) shows an antelope being chased by a group until it collapses. Persistence hunting can also be used on the fastest land animal, the cheetah. In November 2013, a group of herdsmen from northeast Kenya ran down and caught cheetas who had been worrying their goats.
Mechanical to Kinetic Energy conversion
(this is my own pet theory)
I wrote a short story a while back that involved a technical description of how a hammer works. A hammer is a force amplifier, converting mechanical work into kinetic energy.
This got me thinking about running, especially running in cushioned shoes. I wondered if we effectively have a sensor in our heels for mechanical energy, but no kinetic sensors in the legs or anywhere up the spine. Thus the kinetic shock wave that a heel strike turns into is not detected, as there are no sensors to detect it. Before we became shoe wearers our bodies already had all the protection they needed at the point of contact. The mechanical impact felt would have ensured we stopped landing on our heels due to pain, and altered our gaits accordingly. However the modern runner with their inch of padding is ‘protected’ from the mechanical shock of impact by the padding, but what they don’t feel is the kinetic energy wave that this impact is converted into. I’m betting it’s this kinetic energy wave that’s responsible for most runner’s problems. Bad backs, ankle trouble, shin splints, patello-femoral pain syndrome, medial tibial stress syndrome, planter fasciitis, achilles tendonitis, runners knee, they could all be created by this kinetic shock wave that our bodies are not designed to detect.
This of course is just a theory, I’m just waiting for someone to come along and run a study to try and prove it. Either way I think it’s an interesting abstraction/metaphor for explaining the unfelt damage being done to your legs in cushioned running shoes.