The phrase "shin splint" is a generic term that describes pain in the lower leg, either on the medial (inside) or lateral (outside) side of the shin bone. This pain usually begins as a dull ache that can't be pinpointed; it can be felt along the entire region where the muscle attaches to the bone.
Early on, exercisers will usually feel pain only at the beginning and end of their workouts. But over time the discomfort becomes more severe, lasting throughout workouts and striking even when you're not exercising, like when getting out of bed.
Technically, shin pain can be caused by a number of conditions, such as tendonitis, periostitis (inflammation of the membrane covering the bone), or a stress fracture. Considering that the placement, causes, and treatment of these three injuries are often the same, the term "shin splint" became a simple way to label the injury.
Shin splints almost always occur in sports that involve running or jumping, such as jogging, dancing, gymnastics, and more. Even walkers can experience shin splints. Contrary to popular belief, they do not always represent a stress fracture of the shin bone (tibia), although stress fractures can be one of the reasons for lower leg pain.
What causes shin splints?
Doing too much too soon. Often people with a lot of enthusiasm start an exercise program too aggressively. It is important to gradually progress in your running or conditioning program, allowing for adequate rest between workouts.
Increasing the intensity or duration of your workouts. Overuse syndrome typically occurs when someone does too much and continually strains the muscles of the lower leg. Increasing your distance or intensity by more than 10% per week would make you a prime candidate for shin splints—especially if you don't cross-train to diversity your program.
Your shoes. Quality running and cross-training shoes are designed to give the best anatomical support. If your shoes are broken down or old—even when the soles or top appear fine—then they have lost their ability to control the rotation of your foot and absorb shock. This "breakdown" usually occurs after 400-500 miles of wear.
The surfaces on which you exercise. Hard surfaces can cause and aggravate shin splints. The optimal surface for running and aerobics should absorb shock, such as an all-purpose track or grassy surface.
High impact exercise. Running sprints, running uphill, jumping, and repetitive impact exercises can all cause shin splints.
Your anatomy. Fallen arches (flat feet), knocked or internally rotated knees, very high arches and over rotation of the foot are all prime causes of shin splints. An orthopedic physician, athletic trainer, or physical therapist can help identify mechanical problems and may prescribe orthotics (custom shoe inserts) as well as strengthening and stretching exercises.