Six-minute walk distance as a measure of functional exercise capacity in multiple sclerosis

Purpose. We hypothesised that six-minute walk (6MWT) distance of patients with ambulatory multiple sclerosis (MS) would differ from age-matched healthy control subjects. We also investigated the contribution of demographic, physical and physiological factors to impaired functional capacity in MS. Method. Thirty MS patients and 30 healthy subjects participated in this study. Respiratory muscle strength was measured. Pulmonary function test and 6MWT were performed. The Barthel Index (BI) was used to assess activities of daily living, and the Modified Ashworth Scale was used to determine spasticity. Symptomatic fatigue was measured using the Fatigue Severity Scale (FSS). Results. Pulmonary function and respiratory muscle strength of ambulatory MS patients were significantly lower, and baseline heart rate and fatigue perception were significantly higher than were healthy controls (p < 0.05). MS patients reached a significantly higher exercise heart rate, and walked significantly shorter distance than did healthy subjects (p < 0.05). The BI score, baseline heart rate and FSS score together accounted for 81 percent variance in 6MWT distance of MS patients (p < 0.05). Conclusion. The shorter distance covered during a 6MWT is determined by the limitations in activities of daily living, resting heart rate and subjective symptomatic fatigue in ambulatory patients with MS. Respiratory muscle weakness, lung function and level of neurological impairment do not contribute to impaired functional exercise capacity in these patients.