Abstract
Rotator cuff-related shoulder pain (RCRSP) is the most common musculoskeletal condition of the shoulder joint and can cause profound disruption to activities of daily living and participation in valued activity. The negative sequelae of RCRSP continues to fuel the ongoing pursuit of effective treatments to help manage pain and disability. Exercise therapy is the most recommended treatment for RCRSP, because it out-performs no treatment and usual care comparators and is generally well received by patients. However, while exercise therapy for RCRSP has a rich literature investigating its effectiveness, much less research has explored how and why it causes an effect. In other words, the causal mechanisms underpinning a reduction in shoulder pain or an improvement in shoulder function through engaging with an exercise program for individuals with RCRSP is currently obstruse. At the commencement of this research program this was a substantial knowledge gap. The studies in the thesis are an attempt to contribute to the diminution of this knowledge gap and provide a foundation for future research.Chapters 1&2 introduce RCRSP and its history, briefly describes common treatment options for RCRSP and outlines the importance of causal explanation in health science. The philosophical foundation that guides this research program is introduced and explained, as well as the research gaps, questions, and aims this thesis intends to explore.
Chapter 3 is an editorial that pithily summarises the current evidence-base concerning possible mechanisms of clinical improvement through engaging with a resistance exercise program for RCRSP. The editorial of Chapter 3 supports a more comprehensive analysis of causal mechanisms in the following chapters and functions as a philosophical entrée for the remainder of the thesis. It outlines the uncertainty surrounding how and why exercise may help an individual with RCRSP, and specifically challenges the prevailing view that ‘getting stronger’ or ‘optimising scapular position or motion’ is what’s responsible for a positive clinical outcome with exercise therapy.
Chapters 4-6 explore the views of clinical researchers, clinicians, and patients about how and why they believe exercise to be beneficial for RCRSP. The outcomes of these chapters and their corresponding studies reveal commonalities and discrepancies among the different stakeholders. The major through-line connecting the stakeholders is that exercise was hypothesised to work predominately via neuromuscular mechanisms (changes to muscle strength and motor control for example). Differences existed at the level of importance attached to psychosocial mechanisms, with patients and clinicians more likely to invoke these mechanisms to explain the effect of exercise compared to clinical researchers. Chapter 6 is a qualitative study that identified a positive experience with exercise therapy is context dependent, most prominently on the relationship between clinician and patient and the perceived individualisation of the exercise program.
Chapter 7 critically discusses the current uncertainty and limitations of the evidence-base regarding exercise therapy for RCRSP, the problems this may present for clinicians prescribing exercise in clinical practice and offers considerations and strategies to help navigate identified uncertainty. Chapter 8 explores whether the best way to judge the efficacy and effectiveness of exercise therapy for RCRSP is strictly through randomised controlled trials and their associated effect sizes. It was decided the Bradford Hill viewpoints of causality could be usefully applied to the exercise for RCRSP literature to evaluate its causal claim. The findings of this review could not refute or corroborate the causal claim of exercise therapy but does highlight modifiable limitations in the literature that may warrant consideration and rectification.
Chapter 9 is the concluding chapter of this thesis. It contextualises the findings of this research program with the wider evidence base, acknowledges the strengths and limitations of conducted research and provides recommendations for future research. This research program maps and critically discusses the causal mechanisms that may underpin the effectiveness of an exercise program for an individual with RCRSP from a variety of perspectives. However, it must be acknowledged, there is still considerable research to undertake and progress to be made in order fora satisfactory explanation of the effect of exercise to be formulated. In the spirit of collaborative and iterative science, it is hoped this thesis may serve as a stepping stone on a continued pathway of discovery.
| Date of Award | 2025 |
|---|---|
| Original language | English |
| Supervisor | Wayne Hing (Supervisor), Ben Schram (Supervisor) & Jeremy Lewis (Supervisor) |