The number of injuries that occur during racket sports can be reduced with the proper conditioning and training, choice of equipment, and care of the court. Mild sprains of the ankles and wrists, blisters, and muscle cramps and stiffness are a few of the minor occurrences, but severe injuries, such as pulled hamstrings, shoulder dislocation or separations, lower back pain, and torn abdominal muscles are also common. Although many injuries occur when muscles are overused and overworked, playing on surfaces that don't provide enough cushion can also cause problems. Surfaces such as cement, asphalt, or synthetic courts can cause knee or back injuries, or an inflammation of the tendons in the front of the lower leg, known as shin splints. Tennis elbow, another common injury, can be caused by the repetitive use of the arm that results in small tears (tehrz) in the tendon at the elbow joint. Although some injuries are unavoidable, warming up by stretching or jogging about 10 minutes prior to playing can help prevent many of them. Keeping a first-aid kit nearby and knowing how to use it can be helpful when treating injuries such as blisters and abrasions. For more information on racket-sport injuries, contact an orthopedic or sports medicine professional.