Shoulder Pain Physical Therapy Frisco, Why Most Treatments Fail Your shoulder is one of the most mobile joints in your body. That mobility depends on everything around it working correctly. When it doesn’t, the shoulder becomes the “end of the chain” that takes the stress. Most shoulder pain is influenced by issues like: Poor thoracic spine mobility (upper back stiffness) Scapular control dysfunction (how your shoulder blade moves) Weak or uncoordinated core engagement