Dr Irene Davis of Harvard University and a Fellow of the American College of Sports Medicine studied the effects of running barefoot as well as running with minimal footwear.
According to her, minimal footwear with a slight padding below allows the feet its complete movement and also offers protection to the sole. Infact, cushioned running shoes may actually encourage runners to land hard on the heel. Running barefoot is also very helpful for flat footed people.
"When you land on your heel you end up with a very quick rise to peak in the force that your body experiences. That completely goes away when you run barefoot because you land on the ball of your foot. That had been shown previously when you take shod runners and have them take their shoes off."
Explaining that runners running barefoot, automatically stop landing on their heel, she said, "We've basically deconditioned our feet by wearing shoes and by wearing very robust motion controlling and cushioning shoes, which takes away some of the function of the foot. And when you land on the ball of your foot, even though it's just slightly on the ball, the calf muscles have to work harder and you get soreness in the calf. You have to take it slowly so that the anatomy can adapt; and it will adapt but it takes time."