Better posture can help ease shoulder pain from impingement
Source: UT Sandiego
Shoulder pain from impingement occurs frequently as the rotator cuff tendons and sometimes a bursal sac get pinched under the roof of the shoulder blade or the acromion. People with a downward slope of the acromion, or who have developed bone spurs from arthritis in the adjacent acromioclavicular (AC) joint, are more susceptible to developing such impingement.
The mechanism causing this disorder may be a gradual or sudden elevation of the ball of the shoulder joint, squishing the described soft tissues against the acromion roof. The rotator cuff muscles are responsible for keeping the ball of the shoulder joint down and away from the roof as we elevate the arm.