Why does running cause shin splints?

Shin splints are properly called medial tibial stress syndrome and is really not a single medical condition. Instead it is a syndrome of other underlying problems. These may include overpronation of the foot, which may cause an overstretching of the muscles of the lower leg, stress fractures of the lower legs or irritated and swollen muscles from an overuse. These are common injuries and have been reported as 13% of all running injuries.