Shoulder impingement is a common injury that occurs when the tendons or bursa in the shoulder become compressed or pinched. This can cause pain, weakness, and limited range of motion in the shoulder and it can occur due to a variety of factors, including:

1. Overuse or repetitive overhead movements: Activities that involve repeated overhead movements, such as throwing a ball, swimming, or painting, can lead to shoulder impingement over time.

2. Muscle imbalances: Weakness or tightness in certain muscles around the shoulder can cause the joint to function improperly, leading to impingement.

3. Poor posture: Poor posture, such as hunching forward or slouching, can alter the alignment of the shoulder joint, increasing the risk of impingement.

4. Bone spurs or other structural abnormalities: Sometimes, bone spurs or other structural abnormalities in the shoulder joint can narrow the space between the bones, leading to impingement.

5. Trauma or injury: A sudden injury or trauma, such as a fall or a blow to the shoulder, can cause impingement.

Overall, shoulder impingement can occur due to a combination of factors, and it is important to address the underlying causes to prevent further injury and promote healing.

Physical therapy is an effective way to rehabilitate shoulder impingement. The goals of physical therapy are to reduce pain, improve shoulder range of motion, and strengthen the muscles around the shoulder.

Here are a couple of exercises that may be included in a physical therapy program for shoulder impingement:

Shoulder blade squeezes, Scapular retractions, Wall slides, External rotation and Internal rotation.

It's important to work with a licensed physical therapist who can assess your specific needs and develop a personalized treatment plan to avoid further injury. They may also incorporate other modalities such as manual therapy, ultrasound, or electrical stimulation to aid in your recovery.