Healthy controls The control subjects will be received at the neurological department of Aarhus University Hospital at Nørrebrogade. Their muscle-strength will be measured by the Dynamometer; the measurements will take approximately 2 hours. Afterwards, they will be driven, by the hospital minibus, to the MR center at Skejby University Hospital, where the MR-scanning will be performed. The total time for the scanning, included changes of clothes, information and scanning, will take 1,5 hours. In case that it´s not possible to perform both the physical examinations and the scanning on the same day, the scanning will take place another day, within the following 7 working days.