Fatigue in MS: From Invisible to Measurable

Inclusion Criteria: * Diagnosis of relapsing remittion, primary progressive or secondary progressive MS * Age: 18-60 years * Ability to perform the foot-tapping task * Ability to walk at least 20 meters (with or without walking aid) Exclusion Criteria: * Dimethyl fumarate, fingolimod or alemtuzumab treatment, since these medications have a strong influence on the immune system As a result of these treatments, there are few to no immune cells circulating in the blood, meaning we cannot find our population of interest in the blood. * Change in medication 6 weeks before the start of the study (including medication not related to MS) - MS relapse within 6 weeks of the start of the study * Had an infection in the last month - Received a vaccination in the last 14 days - Pregnant or pregnancy in the last 6 months * Having a psychiatric disorder * Having a neurological disorder other than MS * Having cognitive or communicative problems that makes it hard to follow instructions