My research aims to better understand the physiological, neurophysiological and biomechanical determinants of fatigue, during extreme exercise (ultra-endurance, altitude) or in the pathological domain (e.g. neuromuscular diseases, cancer, aging, ICU). My work on acute fatigue in athletes also serves as a model and a field of methodological development for clinical research. In collaboration with many national and international researchers, my integrative approach ranging from muscle biology to sleep and biomechanics of locomotion has the primary goal of better understanding the etiology of chronic fatigue in patients. In particular, I explore the potential role of impaired resistance to acute fatigue (i.e. during exercise) and its central (corticospinal excitability) and peripheral (muscle) origins in the extremely complex (and therefore poorly treated) symptom of chronic fatigue. The target populations are mainly cancer and multiple sclerosis patients, those who have been in intensive care units and the elderly. The ultimate goal of this research program is to personalize the treatment, and in particular the type of physical training, offered to patients in order to improve their quality of life and reduce healthcare costs.