Incomplete ruptures of the inside of the calf muscle often result from a sudden contraction of the calf muscles. Commonly occurring in athletes—especially, as the name suggests, tennis players—this injury causes a sudden, sharp, or burning pain in the leg. In some cases, there may be an audible noise when the injury occurs. In most cases, this injury requires that the affected person stop all activity immediately. At that time, the patient should put something cold on the site of the injury, apply a compression bandage to reduce bleeding in the small blood vessels in the calf, and elevate the leg. Ongoing symptoms of tennis leg include reduced mobility in the ankle, weakness when attempting to stand on the toes, and bruising and swelling behind the leg. The affected muscle—called the plantaris—attaches just above the knee on the outside of the leg, runs across the back of the calf, and inserts into the heel bone. The plantaris helps the larger calf muscles flex the foot and move the ankle. Typically, tennis leg occurs following force or trauma to the leg when the knee is in a straight position. In addition to the immediate treatments described above, patients may begin gentle stretching and mobility exercises a couple of days after the injury occurs as long as it is not painful to do so. The patient can then move into strengthening exercises guided by a medical professional, such as a physical therapist.