1 Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark; The Danish MS Hospitals, Ry and Haslev, Denmark. Electronic address: lhvid@ph.au.dk.
2 Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark.
3 Department of Regional Health Research, University of Southern Denmark, Odense, Denmark; MS Clinic of Southern Jutland, Department of Neurology, Sønderborg, Denmark.