Abstract

Chronic low back pain (CLBP) is one of the leading causes of disability worldwide. Concussions are sustained by 69 million people worldwide every year and produce €33 billion worth of health-care related costs in Europe alone. Both of these spine-related pathologies have been linked to deficits in the lumbar paraspinal musculature in general and the lumbar multifidus muscle in particular. These deficits may have implications for the functional capacity of the paraspinal muscles as well as for the proprioceptive and vestibular systems. Chapter 1 is a literature review. I provide background information about the epidemiology and pathophysiology of CLBP and concussions and discuss the implications for the paraspinal musculature. A survey of imaging techniques for quantifying changes to the paraspinal musculature is provided. Transcutaneous electrotherapy is a common treatment for CLBP but the impact of electromyostimulation (EMS) – a variant designed specifically to impact muscle – on lumbar multifidus morphology and function has not been extensively studied. Chapter 1 also provides an overview of the mechanisms of action of the different iterations of this modality, with a focus on (EMS). Chapter 2 identifies the gaps in the literature and provides rationales and hypotheses for my PhD thesis and related research projects. A significant portion of my dissertation is focused on the effect of EMS on paraspinal muscle morphology and function in CLBP patients, and was investigated through both original research projects and a systematic review. Chapter 3 describes the effect of a 10-week EMS intervention on lumbar multifidus morphology and function in CLBP patients (Manuscript I). Chapter 4 explores the acute effects of a single EMS on lumbar multifidus stiffness in this population (Manuscript II). Chapter 5 is a systemic review and meta-analysis of the effect of transcutaneous electrotherapy on observer-rated measures of low back function (Manuscript III). Chapter 6 switches focus to investigate the impacts of sports-related concussion (SRC) on both lumbar and cervical paraspinal muscle morphology, among other outcomes (Manuscript IV). Finally, Chapter 7 summarizes the findings from my research projects, identifies some common links between both my different projects and previous research, and offers suggestions for future research.