Experimental design Two-pronged, case controlled study. Randomization of 20 MS patients into a Group "Exercise" (n=10) - that perform 30 minutes cycling on an Ergometer - or "Relaxation (n=10) that perform relaxation in a comfortable and quiet environment. Both groups crossover at t2 into the respective Group. The study is set into the normal rehabilitation program and participants are given physician clearance, are informed about the study and give their written consent before the study starts.