"You have (rotator cuff related) shoulder pain, and to treat it, I recommend exercise." A scoping review of the possible mechanisms underpinning exercise therapy.

BACKGROUND: Exercise is considered to be both essential and at the forefront of the management of rotator cuff-related shoulder pain (RCRSP). Despite this, many fail to substantially improve with exercise-based treatment. Hence, expanding the current knowledge about the possible mechanisms of exercise for RCRSP is critical. OBJECTIVE: To synthesise the range of mechanisms proposed for exercise in people with RCRSP. DESIGN: Scoping review METHODS: A systematic search of the Physiotherapy Evidence Database (PEDro) was conducted from inception to July 3, 2022. Two reviewers conducted the search and screening process and one reviewer extracted the data from each study. Randomised clinical trials using exercise for the management of RCRSP of any duration were included. The PEDro search terms used were "fitness training", "strength training", "stretching, mobilisation, manipulation, massage", "upper arm, shoulder, or shoulder girdle", "pain", and "musculoskeletal". Data were analysed using quantitative and qualitative approaches. RESULTS: 626 studies were identified and 110 were included in the review. Thirty-two unique mechanisms of exercise were suggested by clinical trialists, from which 4 themes emerged: 1) neuromuscular 2) tissue factors 3) neuro-endocrine-immune 4) psychological. Neuromuscular mechanisms were proposed most often (n = 156, 77%). Overall, biomedical mechanisms of exercise were proposed in 95% of cases. CONCLUSIONS: The causal explanation for the beneficial effect of exercise for RCRSP in clinical research is dominated by biomedical mechanisms, despite a lack of supporting evidence. Future research should consider testing the mechanisms identified in this review using mediation analysis to progress knowledge on how exercise might work for RCRSP.

Rotator Cuff-Related Shoulder Pain: Is It Time to Reframe the Advice, "You Need to Strengthen Your Shoulder"?

SYNOPSIS: Progressive resistance exercise, in isolation or in combination with other noninvasive therapies such as therapeutic touch, is the first-line approach to managing nontraumatic rotator cuff-related shoulder pain (RCRSP). Resistance exercise may be effective for people with RCRSP secondary to improving mechanical features of the shoulder, including strength, kinematics, and muscle timing and activation. However, strength gains are often small and clinically unimportant when measured during clinical trials. In this Viewpoint, we argue that clinicians should (1) continue to prescribe resistance exercise when managing RCRSP, and (2) embrace the broad biological mechanisms underpinning the efficacy of resistance exercise. Any benefit is governed by more than simple mechanical changes. The clinical message must go beyond the idea that the patient's weak, deconditioned, or frail shoulder is the basis of his or her pain, and all the patient needs to do is to get strong. J Orthop Sports Phys Ther 2021;51(4):156-158. doi:10.2519/jospt.2021.10199.