Is fatigue associated with cardiorespiratory endurance among patients suffering from multiple sclerosis?

OBJECTIVE: Fatigue is the most common and disabling symptom among patients suffering from multiple sclerosis (MS). From the initial stages of the disease, a physical deconditioning is also observed among these patients. The aim of this study is to assess the cardiorespiratory endurance (i.e. exercise tolerance functions) and self-reported fatigue, as well as their associations, among patients suffering from MS with mild disability (expanded disability status scale≤4). MATERIALS/PATIENTS AND METHODS: 21 patients with MS (15 women; age: 26-64 years, median 46 years; duration of disease: 0.33-48 years, median 7.25 years; EDSS 0-4, median 2.5; clinical forms: relapsing-remitting 16, 4 primary progressive, secondary progressive) were evaluated. Cardiorespiratory endurance was assessed by a maximal exercise test on a cycle ergometer, from which different indices were extracted: VO2-max, oxygen uptake efficiency slope (OUES) and physical working capacity at 75% of maximal heart rate (PWC75%). Perceived fatigue, anxiety and depression and quality of life were respectively assessed by the following questionnaires: modified fatigue impact scale (MFIS), fatigue severity scale (FSS), hospital anxiety and depression scale (HADS) and short form health survey (SF-36v2). RESULTS: The majority of the patients (n=13, 62%) presented a pathological level of perceived fatigue, based on the FSS criterion (FSS>5). The cardiorespiratory endurance indices are decreased in all the patients, compared with the normative values from the general population. Low-to-moderate negative correlations (p