Shin splints—a painful spasm in the lower legs—are one of the most common running injuries, though they can also develop from many other activities. The condition is caused by an overload on the shinbone and the connective tissues that attach your lower-leg muscles to the bone. To keep the problem at bay or heal it ASAP, experts recommend:

* Change your shoes. Running in worn-out sneakers is one of the most common causes of shin splints. Replace your shoes every 300 miles (or every year if you don't run a lot).

* Get arch supports. Try out a couple of different pairs of insoles or go to a running shop to get fitted for custom arch supports.

* Stretch your calves. Lack of ankle mobility is a major cause of the condition.

* Cut back. Don't run downhill and avoid playing basketball or tennis until the pain subsides.