Level Of Pain Catastrophizing Determines If Patients With Longstanding Subacromial Impingement Benefit From More Resistance Exercise: Pre-Defined Secondary Analyses (SExSI-Trial)

Through pre-planned secondary analyses of a pragmatic RCT, we aim to investigate 1) if adding a large resistance exercise dose to usual care is superior to usual care alone for improving pain mechanisms and pain catastrophizing, in patients with longstanding subacromial impingement, 2) the modifying effect of pain mechanisms and pain catastrophizing on intervention effectiveness in improving shoulder strength and disability, and 3) the impact of shoulder strengthening exercise dose and central pain mechanisms on changes in shoulder strength and disability from baseline to four-month follow-up.