When the arms and shoulders are overstretched, muscles, tendons and ligaments may be lengthened past normal range of motion causing shoulder instability. Shoulder instability increases the risk of shoulder injuries such as strains, sprains and dislocations. When a shoulder injury occurs, consult a medical profession for treatment.
D.L. Morgan and colleagues report in a 1999 "Journal of Applied Physiology" article that overstretched muscles deactivate and lose their ability to contract normally, therefore decreasing joint stability. Overstretched ligaments, which attach to and stabilize bones of the shoulder, also create joint instability. Decreases in arm muscle activation and ligament stabilization increases the risk of shoulder injuries.
Individuals at Risk
Athletes more prone to overstretching and shoulder injuries are baseball pitchers and gymnasts. Sports in which athletes are susceptible to acute overstretching of the arms due to a fall, reach or tackle include football, volleyball and baseball. Yoga participants who perform positions improperly may also overstretch the arms and sustain shoulder injuries.
Muscle and Tendon Strains
When the arm overstretches, the muscles surrounding the shoulder may become strained or pulled causing a torn muscle. The tendon to which the muscle attaches may also overstretch and strain. A muscle or tendon strain may be a partial tear or a complete rupture. Symptoms include point tenderness, pain and swelling. To treat a suspected muscle or tendon strain cease physical activities, apply ice and seek medical attention.
Ligaments attach the bones that make up the shoulder joint. These ligaments are inflexible. So when overstretching of the shoulder joint and arm occurs due to a fall or reach for a ball, the ligaments are sprained or lengthened beyond their normal limits. Symptoms include pain and swelling; treatment is rest and ice. Consult a medical professional for treatment of severe ligament sprains.
Dislocations and Subluxations
Overstretching of the ligaments and muscles around the shoulder increase the instability and risk of dislocation or subluxation, according to Michael J. Alter in his book "Science of Flexibility." A shoulder dislocation occurs when a shoulder joint is out of the socket and needs to be reduced or put back manually. A subluxation of the shoulder happens when it goes back into socket naturally. A shoulder dislocation or subluxation overstretches ligaments, further increasing the risk of more dislocations and shoulder injuries. Symptoms include pain, numbness and decreased range of motion. After a dislocation or subluxation, seek medical attention immediately. Do not try to reduce a dislocated shoulder.
The glenoid labrum is cartilage that surrounds the shoulder joint to help stabilize the shoulder. Overstretching of the arms may increase the wear and tear on the labrum, resulting in fraying and tearing. Arne Kristian Aune states in the book "Clinical Guide to Sports Injuries" that a torn labrum may also occur secondary to a dislocation or subluxation. Symptoms include catching, pain and decreased range of motion. Consult a doctor for treatment, which may include surgery.
- “Journal of Applied Physiology”: Early Events in Stretch-Induced Muscle Damage
- Gymnastics Rescue: Shoulder Injuries in Gymnastics
- “Clinical Guide to Sports Injuries”: Arne Kristian Aune, 2004
- “Sports Injuries”: Stephen R. Bird, Neil Black, Philip Newton
- “Science of Flexibility”: Michael J. Alter, 3rd Ed.