Endurance running: Bare or shod
"I run with shoes (when I run), but I do like to run barefoot on the beach whenever I can."
[Yes, that is where bipedal running began, at the sea shoreline, no shoes, no flippers, just feet.]
`the foot on the pre-pastoralist group is uniformly "healthier" than the modern groups.'
Ironically, even though Zipfel and Berger acknowledge that pre-pastoralist people show some signs of `wear and tear' that might arise from much greater amounts of walking, constant travel and nomadic foraging, this heavy use pattern did not correlate with higher rates of a wide range of bone pathologies.
In a study of shoe-wearing and habitually barefoot Chinese populations, Sim-Fook and Hodgson (1958: 1059) found:
The feet of the non-shoe-wearing populations showed thick soles with prominent skin creases apart from many minor lacerations due to traumata. The pachydermatous [!!] skin on the sole of the foot had an extraordinarily thick keratinized layer about 0.5 to one centimeter thick which permitted the individual to walk about without any discomfort. Although thick and tough, the skin was pliable and was marked by deep transverse folds which were similar to the lines of joint flexion found on the palm of the hand
(Before I go any further, `pachydermatous' is the coolest word EVER )
Even though the groups studied spent quite a bit of time standing in water and unshod, Sim-Fook and Hodgson did not find many complaints about foot health, in part because their soles were so resilient and pliable, but also because the unshod did not have the constant low level friction on their feet provided by shoes. Ironically, this constant, low pressure against the foot can produce more severe chronic injury and malformation than the once-in-a-while and completely varied traumas of walking around with naked feet. Since the bones and tissue are, in a sense, being grown inside the shoes, they struggle to conform to some of the spaces and mechanical environments that we give them.
Paleolithic Diet movement seems to overlook a host of problems, such as changes in activity patterns, the difference between wild and domesticated meat animals, the high incidence of parasites and low life expectancy in prehistoric periods, and the likelihood that much of human protein was not coming from delicious medium-rare steak or grilled chicken breasts but rather invertebrates, shell fish, small vertebrates, offal and carrion (that's right, maybe it should be the `Bugs, Clams, Lizards and Roadkill Diet' not quite the same marketing potential as `Eat All the Steak and Chicken You Can!'). I've discussed this in Paleofantasies of the perfect diet Marlene Zuk in NYTimes.