Abstract

Low back pain (LBP) is the most common musculoskeletal disorder globally, and a leading cause of disability, especially when it becomes chronic. Exercise therapy is the most widely used form of conservative treatment for chronic LBP. Due to the link between changes in paraspinal muscle morphology (e.g. atrophy, fatty infiltration) and LBP, many exercise interventions focus on activating paraspinal muscles. Past findings suggest the benefits of exercise for individuals with chronic LBP on patient-reported outcomes, including improvements in pain, disability and quality of life. However, the best type of exercise to improve paraspinal muscle health in chronic LBP is understudied, and therefore, remains unclear. This 7-chapter dissertation aims to use magnetic resonance imaging to comprehensively investigate the effect of different exercise programs on paraspinal muscle morphology and function, and its association with patient-reported outcomes in individuals with chronic LBP. Chapter 1 explains the rationale, objectives, and hypotheses, and Chapter 2 consists of a comprehensive review of the literature. Chapter 3 explains an aquatic therapy protocol. Chapter 4 aimed to investigate the effect of an aquatic therapy program versus standard care on paraspinal muscle morphology and function, and the association of morphological changes with strength and patient-reported outcomes. Similarly, Chapter 5 aimed to investigate the effect of a combined motor control and isolated lumbar extension strengthening program versus general exercise on paraspinal muscle morphology and psychosocial factors, and the association of morphological changes with strength and patient-reported outcomes. Finally, Chapter 6 aimed to investigate the effect of a multimodal exercise program versus no exercise on paraspinal muscle morphology and patient-reported outcomes, and the association of morphological changes with patient-reported outcomes and functional outcomes. Lastly, Chapter 7 summarizes the results of Chapter 4-6 and states the general limitations, recommendations for future research, and conclusions.