The effect of painful exercise on ultrasonographic outcomes in rotator cuff-related shoulder pain: Secondary analysis of a randomized controlled trial

BackgroundThe effects of painful or pain-free exercises on Ultrasound (US) parameters in rotator cuff-related shoulder pain (RCRSP) is still unexplored.ObjectiveTo investigate in chronic RCRSP i) the differences between exercise with or without pain on US outcomes, ii) the relationship between changes in US findings and symptoms.MethodsSecondary analysis of randomized controlled trial. Patients were assigned to exercise with pain or without pain in a 12-week intervention. Acromiohumeral distance, coracohumeral distance, tendon thicknesses of supraspinatus, long head of the biceps (LHB), and subscapularis were measured at baseline, 9, 12, 26 weeks. Correlations between changes in US findings and the primary clinical outcome, Shoulder and Pain Disability Index (SPADI), were investigated.ResultsForty-one patients were analyzed. No difference between groups over time was found (time-by-group interaction: 0.07 ≤ <i>p</i> ≤ 0.85, time effect: 0.24 ≤ <i>p</i> ≤ 0.83). Changes in SPADI and US outcomes (baseline-26weeks) were not correlated, except for LHB (r = 0.45, <i>p</i> = 0.01). While SPADI significantly decreased, LHB non-significantly increased (0.07 mm).ConclusionsExercise with or without pain did not influence subacromial and subcoracoid spaces nor shoulder tendon thicknesses. Increase of subacromial space should not be an objective of rehabilitation programs. LHB activation might be relevant as compensating mechanism for rotator cuff deficiency.Clinical Trial Number: NCT04553289.