Muscles can tear when too much strain is placed on the muscle fibers. The severity of the tearing will determine whether it is safe to exercise or not; a muscle strain occurs when the tiny fibers that make up a muscle begin to tear, and this can be considered a fairly minor injury. A rupture, sometimes known as a torn muscle, is a more severe injury in which the muscle separates entirely from itself or the tendons securing it to bone. If a torn muscle occurs, it is not safe to exercise, and the injury may require surgery for full repair.
Some people refer to muscle strains as a torn muscle, which is technically true: the muscle fibers do tear when the muscle strains. If the injury is not severe, and pain is manageable, it is possible to continue an athletic activity or to exercise with the strained muscle. If pain persists or worsens when exercising, however, the person doing the exercise should stop immediately and rest the muscle to allow it to heal. Torn muscle fibers can worsen if used when exercising, sometimes resulting in a rupture, so if moderate pain is felt after the muscle strain occurs, it is necessary to rest to allow the muscle fibers to heal.
Muscle strains are treated with the RICE method, or rest, ice, compression, and elevation. These practices keep swelling to a minimum and promote quick healing. If possible, the injured person should use the RICE treatment to allow the strained muscles to heal. If the strain occurs during an athletic event, and the pain is manageable, the person participating in the sport can continue to play, though he or she runs the risk of worsening the strain; a torn muscle may result.
Torn muscles are very serious and painful injuries. A full tear, or rupture, will often incapacitate the person, and the muscle may bunch up at one end of its length. Bruising and swelling are likely to occur, and moderate to intense pain will almost definitely occur. When a muscle rupture occurs, the person will need to stop any physical activity immediately — most people are incapacitated by the injury anyway, so further activity is usually not an option — and seek medical attention. The torn muscle will need to be reattached surgically, which will mean a prolonged recovery time during which one will need to rest the injury long enough to allow the muscle fibers to heal. The doctor will indicate when it is appropriate to begin exercising after the torn muscle surgery.