A torn shoulder muscle shows noticeable symptoms shortly after an acute injury or following repetitive wear and tear over time. This means that patients can sustain muscle tears from sudden overexertion, such as overstretching to catch a ball, or from repeatedly placing stress on the same muscle group, such as reaching for heavy items from a high shelf. The American Academy of Family Physicians (AAFP) reports that the onset rate of pain symptoms will help pinpoint the cause of the shoulder pain.
Acute Pain
A tight stretch that results in a torn shoulder muscle may cause a popping or burning sensation at the time of the injury, according to University Sports Medicine. This immediate, local pain may evolve into a more widespread tenderness as inflammation sets in, especially if more than one muscle is involved.
The four muscles of the rotator cuff are also vulnerable to tears during acute injuries to nearby tendons, ligaments, joints and bones. Therefore, shoulder pain may be compounded by trauma such as a fall that causes a fracture or dislocation.
Developing Pain
Muscles that tear little by little due to chronic overuse will bring about a gradual onset of shoulder pain, generally while in motion. This is due to impingement, a condition in which pressure is placed on the rotator cuff by the shoulder bone. It occurs as inflammation slowly sets in and restricts the space for movement.
The AAFP says that shoulder pain occurs when weight is put on the affected muscle or when attempting the type of motions that initially caused the injury. Any activity above shoulder level, regardless of force, can trigger pain, such as washing hair or putting on a jacket.
Muscle Weakness
In addition to pain, rotator cuff weakness can make some daily activities difficult or impossible. The loss of dynamic tension in the shoulder muscle group affects its strength.
As the AAFP notes, diagnostic testing will show reduced ability for flexion, abduction and rotation of the shoulder and arm. This reduction in strength affects the patient's capacity to reach, pull and lift.
Limited Mobility
University Sports Medicine points out that pain, impingement and shoulder muscle weakness all contribute to a diminished range of motion. It may hurt too much to move, or the impingement may be too great to allow the rotator cuff its normal range of movement.
Other factors, such as tears and inflammation in the bursae or tendons, can further restrict mobility, depending upon location. Additionally, shoulder impingement can lead to adhesive capsulitis, or frozen shoulder, which immobilizes the ball-and-socket glenohumeral joint that permits the arm to move in a circular motion.
