Representing the most common category of injury among athletes, sprains and strains affect ligaments, tendons, and bones. Specifically, a sprain is a stretch or tear in a ligament, which is a band of fibrous tissue that connects one bone to another, and a strain is an injury to a muscle or tendon, which is a band of fibrous tissue that attaches a muscle to a bone. These injuries are typically caused by trauma (e.g., a fall or violent impact) that displaces and over-stretches a joint, in some cases tearing surrounding ligaments. Chronic strains, on the other hand, result from overuse of muscles and tendons. Such strains usually result from excessive, intensive training with too few rest periods. Participation in any sport or form of activity—walking included—puts a person at risk for a strain or sprain. The site and severity of these injuries depend on the activity that caused it. Those who participate in basketball, volleyball, soccer, and other jumping sports usually experience sprains or strains in the foot, leg, or ankles. Contact sports that often lead to strains or sprains include football, hockey, boxing, and wrestling. Finally, sports that involve quick-start motions also put athletes at high risk for strains and sprains. These include hurdling, sprinting, jumping, gymnastics, and tennis. Elbow strains often occur with racquet, throwing, and contact sports. Symptoms of a sprain include pain, bruising, swelling, and inflammation at the site of injury. In some cases, the person suffering the sprain may hear or feel a pop in the joint at the time of injury. Symptoms of strain include pain, muscle spasm and weakness, swelling, inflammation, and cramping. If the muscle or tendon is ruptured, the affected person may be unable to move. Treatment of these injuries involves rest, ice, compression, elevation, and physical therapy. In severe cases, surgery may be required.