We were running through Cornwall Park in Auckland recently where we came across a guy running in bare feet. This of course is not entirely unusual in Auckland given the popularity of the bare foot concept, but we'd like to offer a caution to those looking to jump straight out of their shoes and onto the pavement.
When the typical person runs, they're exerting about 3 or 4 times their body weight through their muscles and joints as they land and push off. The body may be able to withstand those forces on the soft sands of Ethiopia, but hard and relentless pavement is another story. Added to that is the greater emphasis bare foot running will place on the calf muscles of the runner. The force of landing has got to go somewhere, and the bare foot runner 'absorbs' much more of that through their calves. The calves also have to work at longer lengths than they would in shoes.
The bare foot approach might have some sound fundamentals, and be sure to see more people jogging the streets in their bare feet, but a word of caution, work into it very slowly and watch out for stones!