The Relationship Between Mechanical Properties of Respiratory and Lower Extremity Muscles and Other Parameters in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease characterised by demyelination and axonal degeneration in the central nervous system, leading to various motor and sensory impairments. Symptoms are classified as cognitive, sensory, and motor, with the most common symptoms including loss of muscle control, muscle weakness, abnormal muscle tone, ataxia, depression, and fatigue. These impairments frequently affect balance and gait, leading to the disabling consequences of the disease. The muscle groups most affected in individuals with MS are the lower extremities, which exhibit significant reductions in muscle strength and function. Research shows that in the early stages of MS, muscle strength in the lower extremities can decrease by approximately 25% compared to healthy controls, with marked deficiencies in muscle activation and increased fatigue. Studies have shown that quadriceps strength is significantly reduced, which can lead to difficulties in walking and maintaining balance. Furthermore, in MS patients, the coactivation patterns of lower limb muscles during walking change, indicating a compensatory mechanism in response to decreased muscle strength. This coactivation can lead to inefficient movement patterns, further exacerbating fatigue and functional limitations. Fatigue is another important symptom associated with MS and affects both voluntary and involuntary muscle contractions. Approximately 65% of individuals with MS report fatigue, and 40% describe fatigue as the most disabling symptom. However, despite the prevalence of fatigue in MS, its exact mechanisms remain unclear. It has been suggested that there may be a correlation between fatigue and increased central arousal to compensate for reduced central activation, and depression has also been reported as a factor that increases fatigue. Fatigue is not only a result of muscle weakness but also involves central mechanisms that impair motor control and muscle activation. Disability in MS is associated with reduced mobility, abnormal gait mechanics, impaired balance and muscle weakness, as well as cognitive and autonomic dysfunction. These impairments typically reduce functional capacity, increase fatigue, reduce independence in activities of daily living, and consequently increase the risk of secondary diseases such as coronary heart disease, diabetes, and obesity. Therefore, a good understanding of fatigue and the mechanical properties of muscle in these patients may play an important role in disease progression. MS can affect the trunk and respiratory muscles as well as the lower extremities. Factors affecting respiratory function include muscle weakness, changes in muscle tone, motor coordination disorders, and postural abnormalities. In addition, MS can affect the centres responsible for respiratory function, leading to clinically significant changes in respiratory control. It has been reported that respiratory muscle weakness can be observed even in the early stages of MS. These studies highlight the complex effect of MS on respiratory function and respiratory muscle weakness. In summary, MS is a multi-faceted disease that can affect the muscles of the lower extremities, particularly the quadriceps, as well as the trunk and respiratory muscles. These impairments can lead to significant functional limitations, affecting the mobility and overall quality of life of individuals with MS and potentially worsening the progression of the disease. Therefore, it is important to understand this condition well and take it into account in clinical management. However, lower limb and respiratory muscle mechanics, respiratory function, fatigue, and depression levels in individuals with MS have not been comprehensively investigated. Therefore, the aim of this study is to investigate the potential relationship between lower limb and respiratory muscle mechanics, respiratory function, fatigue, and anxiety-depression in individuals with MS. Research Hypotheses: H0: The mechanical properties of the respiratory and lower extremity muscles in individuals with multiple sclerosis have no effect on respiratory function, fatigue, and depression levels. H1: The mechanical properties of the respiratory and lower extremity muscles in individuals with multiple sclerosis have an effect on respiratory function, fatigue, and depression levels. This study will be conducted jointly by the Department of Physiotherapy and Rehabilitation, Faculty of Health Sciences, SANKO University, and the Department of Neurology, Faculty of Medicine, SANKO University. MS patients who apply to the Neurology Outpatient Clinic of SANKO University Hospital and meet the inclusion criteria will be included in the study. Patients included in the study will be evaluated at the SANKO University Department of Physiotherapy and Rehabilitation Research Laboratory. The study data were collected using the Case Report Form (CRF), Pulmonary Dysfunction Index (PDI), Modified Medical Research Council Scale (mMRC), Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), and Hospital Anxiety and Depression Scale (HADS). Data contained in the Data Collection Form (DCF) will be obtained using the 30-second sit-to-stand functional assessment test (30sSTT) and laboratory measurement devices including the MyotonPro® digital palpation device (Myoton AS, Estonia) and a portable spirometer (Cosmed, Pony Fx, Rome, Italy). The study data were collected using the Case Report Form (CRF), Pulmonary Dysfunction Index (PDI), Modified Medical Research Council Scale (mMRC), Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), and Hospital Anxiety and Depression Scale (HADS). Data contained in the Data Collection Form (DCF) will be obtained using the 30-second sit-to-stand functional assessment test (30sSTT) and laboratory measurement devices including the MyotonPro® digital palpation device (Myoton AS, Estonia) and a portable spirometer (Cosmed, Pony Fx, Rome, Italy). Healthy individuals of the same age group will be included in the study. The results of healthy individuals will be compared with the results of MS patients.