Shoulders are complex joints, prime for injury. Shape magazine reported in 2012 that a third of weight room injuries affect the shoulder. Repetitive movements in sports, including swimming and throwing, can also lead to shoulder irritation. If you have persistent pain that lasts for days or weeks when you raise your arms forward, to the side or overhead; have a shoulder that feels stiff or limited in its range of movement or that is inexplicably weak, consult your physician.
Soreness in the shoulder is usually a result of strain or damage to the muscles or connective tissues, particularly the tendons and ligaments. The bones are less likely to be the source of the issue. For example, the rotator cuff -- a group of muscles and tendons that hold the shoulder joint together --- is a common site of discomfort. If your rotator cuff is injured, you'll find it painful to reach your arms overhead.
Inattention to form during strength training can cheat you of results and cause you injury. The Journal of Strength and Conditioning Research reported in a 2010 study that a significant number of incidences for shoulder injury can be blamed on improper technique. When performing moves, such as front or lateral raises, military presses and external rotation moves, maintain correct form. Pushups or triceps dips done sloppily can also cause pain in the shoulder. If you're unsure what proper form looks like, consult a fitness professional for guidance. Upright rows, for example, performed with the elbow pulled past a 90-degree angle increase the chance of shoulder impingement.
Instability injuries occur when your shoulder is out of its normal position. The shoulder joint feels out of place, or dislocated from the joint. It causes pain when you reach your arms overhead. A labrum tear is an example of such an injury.
Impingement happens when muscle continually rub along the bones of the shoulder blade. Poor lifting technique, as well as repetitive movement, such as pitching, can cause it. Consult your doctor at the early signs of pain as the inflammation should be addressed before it becomes more serious.
Ignoring soreness, swelling or pain in your shoulder will not make the injury go away. If you try to exercise through a painful shoulder, chances are that you'll exacerbate the existing injury. Seek medical care for nagging discomfort as well as sharp pain. In some cases, work with a physical therapist will show you how to incorporate exercises that appropriately stretch and strengthen the affected area.