Shin splint: An inflammatory condition of the front part of the tibia (the big bone in the lower leg) that results from overuse as, for example, from running too much on hard roads or sidewalks. Shin splints are due to injury to the tendon (called the posterior peroneal tendon) and adjacent tissues in the front (anterior) of the lower leg.

The pain from shin splints is usually noticed early in exercise, then lessens, and reappears later in running. Characteristically, the pain is dull at first but with continuing trauma worsens. It may cause the person to stop running. Treatment involves a multifaceted approach of "relative rest." The aim is to restore the runner to a pain-free state.