Shoulder pain can make everyday activities—reaching overhead, getting dressed, lifting weights, or even sleeping—uncomfortable. One common source of shoulder pain is a problem involving the rotator cuff.
But what exactly is the rotator cuff, and why does it become painful?
What Is the Rotator Cuff?
The rotator cuff is a group of four muscles and their tendons that surround the shoulder joint. These muscles help you lift and rotate your arm while keeping the upper arm bone centered in the shoulder socket.
Because the shoulder has a tremendous range of motion, it relies on coordinated muscle activity and control to move effectively.
The four rotator cuff muscles are:
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
Together, they help provide the stability and movement needed for everything from throwing a baseball to reaching into a cupboard (like the lady in the picture, haha).
What Can Go Wrong?
“Rotator cuff problems” is a broad term. It does not automatically mean that a tendon is torn.
Rotator cuff-related pain may involve tendon irritation or degeneration (sometimes called tendinosis, where the tendon thickens, is painful, and less elastic), inflammation of nearby tissues, or a partial or complete tendon tear.
Symptoms can include:
- Pain when lifting or lowering the arm
- Discomfort with reaching overhead or behind the back
- Shoulder pain that interferes with sleep
- Weakness or difficulty performing everyday activities
- Reduced shoulder movement
These symptoms can overlap with other shoulder conditions, so an examination is important to help determine what may be causing them.
Why Do Rotator Cuff Problems Happen?
There is rarely just one explanation. Several factors can contribute.
1. Repetitive Stress
The rotator cuff works repeatedly during activities such as throwing, swimming, tennis, weightlifting, and overhead work.
When the demands placed on the shoulder exceed its current capacity to tolerate and recover from them, symptoms may develop. A sudden increase in training volume, intensity, or frequency can be particularly challenging.
2. Age-Related Changes
As we get older, tendons can undergo gradual changes in their structure and ability to tolerate load.
Rotator cuff tears become more common with age, and some people have tears without experiencing pain. A finding on imaging does not necessarily mean that it is the source of someone’s symptoms.
3. A Sudden Injury
A fall onto an outstretched arm, a forceful lifting movement, or another traumatic event can injure a rotator cuff tendon.
A sudden injury accompanied by significant pain or weakness deserves prompt assessment.
4. Shoulder Movement and Muscle Coordination
The shoulder does not work in isolation. The shoulder blade, upper arm, trunk, and surrounding muscles coordinate to produce movement.
If movement patterns, strength, mobility, or workload are not well matched to the activity being performed, the demands on the shoulder may change. These factors can be relevant when evaluating shoulder pain, but they do not prove that a particular movement pattern caused a tendon injury.
5. Chronic Subluxation of the Cervical Spine
All of the muscles of the shoulder don’t know what to do unless the brain tells them what to do. What happens when that signal is compromised or not working properly because of nerve root irritation coming from bones in the cervical spine/neck that are out of position or not moving properly?
You guessed it, they don’t work at 100%, which leads to muscle substitution patterns, which leads to some muscles working overtime, which leads to damage to the rotator cuff muscles and tendons.
I would personally argue that in order to correct ANY rotator cuff problem. It cannot be done without looking at the cervical spine as well.
Why Does It Sometimes Hurt During Specific Movements?
Some people notice pain when reaching overhead, lowering their arm, or performing pressing and pulling exercises.
These movements place different demands on the shoulder and its surrounding tissues. Pain may reflect irritation, reduced tolerance to load, or an underlying injury—but the painful movement alone cannot tell you exactly which structure is involved.
That is why simply avoiding every painful movement may not address the underlying issue. The goal is to understand what is happening and determine which activities and treatments are appropriate.
What Should You Do About Shoulder Pain?
A proper assessment considers your symptoms, history, shoulder range of motion, strength, and how your shoulder responds to specific movements.
Depending on the findings, care may involve modifying aggravating activities, progressive rehabilitation, and other appropriate treatment. Imaging or referral to another healthcare professional may be needed when a significant tear or another condition is suspected.
If you experience sudden shoulder pain with substantial weakness after an injury, seek prompt medical evaluation.
The Bottom Line
Rotator cuff problems can develop gradually through repetitive demands and age-related tendon changes, or they can occur after a sudden injury.
Understanding the difference between tendon irritation, degeneration, and a tear is important because not every painful shoulder has the same problem—or needs the same treatment.
If shoulder pain is limiting your workouts, sports, sleep, or daily activities, a thorough evaluation can help identify the factors that may be contributing to your symptoms and guide the next steps.
Don’t guess your way through shoulder pain. Find out what may be contributing to it, and what’s behind it.
We can help!