Shin splints describes a painful condition in which either the shin bone, the connective tissues alongside the shin (or both) suffer damage from running. If the pain only affects the bone and is sharp and severe in one particular location, the problem is probably a hairline fracture of the tibia. The only real solution is to rest until the fracture heals.
Doctors don't fully understand what causes shin splints that affect muscles and connective tissues. The muscles could be inflamed and are pressing against the muscle sheath. Some sports medicine experts suspect that the connective tissue and muscle sheath can slowly tear away from the tibia. In any case, the tearing damages tissues and it can cause pain severe enough to keep even the most dedicated runners off their feet.
Resolving shin splints requires a certain amount of rest, along with frequent icing and elevation to reduce inflammation. Stretching the calves, shin muscles and ligaments also helps. Orthotic shoe inserts may keep shin splints from developing. Overweight runners with shin splints could try shedding some pounds to alleviate the problem.