Strength loss and enhanced neuromuscular fatigue are major contributing factors of impaired functional capacities, exercise tolerance and prognosis in patients with various chronic diseases. These alterations can rely on primary deficiencies of neuromuscular function and/or secondary impairments caused by decreased spontaneous physical activity promoted by a chronic disease. Consequently, muscle weakness and enhanced fatigability are frequently reported symptoms in neuromuscular (inherited or noninherited myopathies/neuropathies), cardiovascular (chronic cardiac failure) and respiratory diseases (chronic obstructive pulmonary disease (COPD)) and idiopathic painful syndromes associated with alteration of nociception (fibromyalgia syndrome). The development of reliable and well-tolerated evaluations of muscle strength, endurance and fatigue is of major interest to better understand the physiopathology of the diseases and to provide relevant outcomes for observational or interventional studies. Artificially muscular electrical stimulation has been recognized as a valuable tool for noninvasive assessments of neuromuscular function at rest and during exercise in human. Recently, magnetic stimulation showed interesting skills to assess both peripheral and respiratory muscles in the clinical field. During this work, we developed tools to assess muscle strength, endurance and fatigue using magnetic neurostimulation and exercise protocols usable in patients. We studied its ability to detect differences related to sex, age and training status. Then we used these procedures in neuromuscular diseases and fibromyalgia syndrome. In COPD patients, we assessed respiratory and locomotor muscle fatigue and studied how these phenomena impact on exercise response and perceived symptoms. In these patients, we also assessed the combined effects of locomotor and respiratory muscle training on these parameters.
