Barefoot running is becoming all the rage nowadays, something I'd like to check out as soon as I'm injury free. It got me thinking about that most amazing of running creatures, the horse. The main problem with running in fancy shoes is that one tends to hit the ground with the heel, transmitting the shock right up the leg and causing all sorts of injuries to knees, shins, hips etc. A barefoot runner is forced to land on their toes, the ankle flexing to act as a shock absorber. Now take a look at the horse. They essentially run all the time on one big toe, or actually one big toenail.
Then there's the cat, that most amazing of jumpers. Their foot is extremely long giving them tons of jumping power. Some people might think that a cat's paws are the same as our feet, but they are really just her toes. The ankle joint is a natural spring, acting as a shock absorber when we run and a giant slingshot for a pouncing cat. The heel juts out and attaches to the large elastic Achilles tendon, which is why it is a lot easier it is to bounce on one's toes than on one's knees.
So it makes sense that bypassing these natural shock absorbers, this springy heel/tendon combination by wearing a pair of padded Nikes and pounding the ground with the heel and long strides will lead to long term joint problems. I suspect that flat feet are also linked to our constant use of shoes.
One advantage we humans have over horses, with our long flexible feet we can really jump a lot better than them.
Well, maybe not. But it does allow us to use a ladder and stuff, let's see you try that mister overly-adapted-to-running horse.
What really got me thinking about this was some disagreement about orthopedic shoes. My son was born quite bowlegged, and is still somewhat pigeon-toed at 3 1/2. The doctor said he'd probably have to wear orthopedic shoes, so I did some research and found that there is little evidence that these things work. It is the stress of walking and running that straightens out baby's legs and feet. The body responds to the stress by strengthening and straightening the bones (unless that is made impossible by something like rickets, get plenty of Vit D, preferably from sunlight). It is amazing to me just how adaptable our bones are. I used to picture them as sticks that our muscles hung off of, but of course they are a dynamic, living organ. Astronauts' bones weaken quite dramatically after just a few weeks in zero gravity. Likewise, rugby players have some of the strongest bones. So my plan is to let my son run as much as possible in bare feet - he naturally runs on his toes already - and let nature hopefully take care of the rest. If that doesn't work, he's gonna have to play under-5 rugby.
Which reminds me of something else: American football. Just as bare-knuckle boxing is safer, albeit bloodier than boxing with gloves, I'd be willing to bet American football is more dangerous than rugby. A combination of the Peltzman effect and interfering with natural feedback mechanisms, like a natural reluctance to smash into one another. This may also apply to bike helmets.