Sports injuries can affect almost any part of your body, including the muscles, bones, joints and connective tissues (tendons and ligaments). The most common type of sports injuries are sprains and strains. Knee injuries can be caused during sports or exercise, the result of overuse, damaged cartilage or a torn ligament. Achilles tendon injuries may occur when the tendon connecting the calf muscle to the heel is damaged. Sports injuries can result from accidents, poor training practices, incorrect clothing or shoes, lack of fitness or not warming up and stretching enough before playing.