MUSCLE IMBALANCE OF
Some of the muscles in your shoulder have opposing roles. When you move your arm, certain muscles contract while their opposing muscles relax. But when a muscle becomes much stronger than its opposing muscle, your shoulder can become unstable. You may have trouble moving it normally. We call this a "muscle imbalance."
This can happen if you have a strength training routine that doesn't work your muscles evenly. It can happen if you perform repetitive motions at your job. You can develop a muscle imbalance if you play a sport that builds some muscles but not others. It can also happen as a result of a shoulder injury.
A muscle imbalance can limit your arm's range of motion. You may feel pain, stiffness, weakness or numbness. Your shoulder may swell. And, you may have muscle spasms.
A muscle imbalance can be treated with physical therapy. Your healthcare provider can create a plan that's right for you.