Evaluation of Muscle Oxidative Capacity Relationship With Muscular Endurance, Fatigue (Multiple Sclerosis).

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. It is characterized by different progressive forms with periods of flare-ups interspersed with phases of remission. MS manifests clinically with signs of multiple neurological dysfunctions as well as less specific symptoms such as fatigue, the prevalence of which is found to be high in these patients and is independently associated with an alteration in their quality of life. Recently, a non-invasive method for assessing maximal muscle oxidative capacity (mVO2) using optical measurement of muscle oxygenation (near-infrared spectroscopy, NIRS) has been described. Measuring tissue light absorption from a skin sensor facing a muscle, makes it possible to distinguish tissue concentrations of oxyhemoglobin (HbO2) and hemoglobin (Hb). The difference in absorbance of Hb and HbO2 corresponds to the balance of O2 supply and consumption in tissue capillaries, allowing calculation of a time constant (kNIRS, min-1) reflecting mitochondrial function. Current literature provides reference values in young healthy subjects and MS patients. This index could therefore constitute a particularly interesting non-invasive indicator of mitochondrial functioning, usable in the clinic.