Systematic reviews and meta-analyses spanning 2-3 decades of research.
So “impingement” has been used to describe anterosuperior shoulder pain caused by a mechanical “impingement” of the subacromial tissues (subacromial bursa, supraspinatus and long head of biceps in particular) against the subacromial arch. What research has shown is that:
- This mechanical encroachment occurs with an equal frequency between symptomatic and asymptomatic shoulders
- The size of subacromial space does not correlate to the occurrence or magnitude of pain associated with “impingement”
- Surgically increasing the size of the subacromial space via subacromial decompression surgery is no more efficacious than placebo surgery for improving shoulder pain that would typically be described as “impingement”
Contributing factors to “impingement” may include poor external rotation strength, but stronger contributing factors are listed below.
As an aside, “muscular imbalance” is a nebulous term at best. Any standards for “muscular balance” are arbitrary. In addition, “muscular balance” in itself is extremely difficult to assess due to issues with reliability and validity of muscle testing techniques, and due to differences in muscle output across ROM
This is exactly the way people should manage and train with pain.
- Reduce the volume of painful activity
- Do stuff that doesn’t hurt as much
- Return to painful activity
- Improve at painful activity over baseline
Pain itself is not an indicator of tissue damage whatsoever. Some of the strongest contributors to long-lasting pain include subconcious hypersensitivity to movement, fear-avoidance of movement, stress, anxiety, poor sleep quality and “maladaptive beliefs” (aka a fragility mindset). Additionally, when discussing long-lasting musculoskeletal shoulder pain, no imaging or clinical tests can accurately assess the cause of shoulder pain. Therefore, the best we can do is develop a stronger, more resilient shoulder complex and manage the volume of (formerly) painful activity you do.