Many argue that since our ancestors did their walking and running barefoot, we ought to too. But, the surfaces we walk on today tend to be more rigid and fewer forgiving than the grass, dirt and even stone roads our ancestors stepped onto. Glass and metal shards are common on roads and were not a significant concern a few century ago.
There are different types of feet. Many people have high arch feet plus some individuals have really low arch feet. Some foot types may adapt well to barefoot running, but that doesn't mean all foot types will. The mechanics of the foot are extremely complicated. Those who overpronate (rotate in) and also have a flexible and flat foot type, typically require a more supportive shoe and sometimes a custom made orthotic. People with a really rigid, high arch foot type, place a tremendous amount of pressure on the outside of their feet and may need a shoe or insert to assist even this pressure out. These two individuals would definitely end up with injuries when they attempted to run barefoot.
Barefoot proponents declare that the shod foot (foot enclosed in a shoe) becomes weak with time when it's constricted. They also claim that your body is unable to sense the floor and adapt appropriately. This inability to sense and adapt appropriately results in injury. The body spends more energy when running inside a shoe, than when running barefoot. Some runners declare that the few scratches on their feet were a smaller amount painful compared to blisters they ordinarily have to cope with following a half or full marathon.
The scientific evidence supporting barefoot running is lacking. Several small research has supported barefoot running. One study within the Internal Journal of Sports Medicine discovered that there is actually less impact on the feet while running barefoot due to the way your body adjusts towards the impact. Another study discovered that the body uses about 4% more energy while running in shoes as compared to running barefoot. In underdeveloped countries with both shod and unshod feet, comparisons have shown a higher rate of injuries within the shod foot.
Opponents don't find these studies convincing and claim that these studies were too small or not completed properly. They point to the fact that the study in underdeveloped countries and point out that this tells us hardly any about injuries and gratifaction in developed countries.
Those opposing barefoot running achieve this for a lot of reasons. Podiatrists, in general, are the more vocal towards barefoot running. The main reason for opposition is foot protection. Puncture wounds are the greatest concern for those running without any protective shoe gear. Many podiatrists feel that blisters and injury are due to ill-fitting shoes, not every shoes.