Why Does My Shoulder Only Hurt When I Move My Arm, But Feels Fine At My Side?
This is one of the most common shoulder pain questions we hear in our studio:
Just this week, Brooke, a 49-year-old from Encinitas, asked:
“For the past several weeks my shoulder feels fine, as long as I don’t use my arm. But as soon as I try to reach or lift something, I get pain down the outside of my arm. Why does my shoulder do that?”
Brooke’s story is familiar. Like many others, she hoped it would go away on its own. When it didn’t, she turned to Google and YouTube for quick fixes—without relief. Now, she’s experiencing one of the most common presentations of shoulder pain: pain-free at rest, sharp pain with movement.
When Does Shoulder Pain Usually Show Up?
Clients often describe pain when:
Fastening a bra
Putting on or taking off a jacket
Sleeping on the painful shoulder
Reaching to the top shelf
Grabbing a wallet from the back pocket
Turning off the alarm clock
Pulling a gallon of milk from the fridge
Fastening a seatbelt
Exercising (push-ups, overhead lifts, pull-ups, CrossFit)
Playing sports (golf, tennis, throwing, etc.)
Do any of these sound familiar?
If so, you’ve probably wondered: What exactly is causing this pain?
The Internet Trap: Too Many Possible Diagnoses
Search “shoulder pain when lifting arm” and you’ll find endless possibilities:
Bursitis
Tendinitis
Impingement
Rotator cuff tear
Frozen shoulder
Labral tear
Arthritis
Nerve entrapment
…and the list goes on.
No wonder it’s confusing. And here’s the problem: trying to self-diagnose often delays healing and can make things worse.
Think about it—if your car’s transmission blows, you don’t try to rebuild it yourself. If your tooth aches, you don’t attempt a root canal in your bathroom. The human body deserves the same specialist attention.
Why Your Shoulder Hurts When You Move
The shoulder is the most mobile (and complex) joint in the body. It relies on 17 different muscles, with the rotator cuff being the key stabilizer group.
The supraspinatus muscle, one of the rotator cuff muscles, passes through a tight tunnel between the upper arm bone (humerus) and the shoulder blade. If that space narrows—because of posture, tight muscles, or repetitive movements—the supraspinatus gets pinched. That’s when you feel the sharp pain.
The Three Biggest Culprits
Overhead activity – Repeated overhead movements (painting, lifting, throwing) put the rotator cuff in its weakest position.
Improper exercise technique – Going “too hard, too soon” or skipping proper shoulder stability work.
Poor posture – Slouching forward compresses the shoulder joint, reducing space and increasing irritation.
Will It Go Away on Its Own?
Unfortunately, no. You might have good days, but without changing what’s causing the irritation, the pain always returns—and may get worse over time.
How Physical Therapy Helps Shoulder Pain
The good news? With the right stretches, strengthening exercises, and posture corrections, shoulder pain can often be resolved without surgery or injections.
Here’s what physical therapy does:
Loosens tight muscles to increase joint space.
Strengthens supporting muscles (especially between the shoulder blades) to restore alignment.
Improves posture so your shoulder moves freely without irritation.
Guides you in safe, progressive exercises so you don’t “go too hard, too early.”
Even simple changes like squeezing your shoulder blades together while sitting or imagining a string pulling you tall can help reduce daily strain.
Take the Next Step Toward Relief
If you’ve been struggling with shoulder pain for more than 10 days, chances are it won’t just “go away.” Like Brooke, you may need expert help to get lasting relief.
Book a complimentary discovery call HERE.
