All randomized patients are recommended outdoor walking with NP at least 30 minutes at least three times per week. The SET group in addition receives in-hospital muscle exercise therapy in a group supervised by a physiotherapist three times weekly during six months. The HET group patients perform the same muscle exercise therapy at home with feedback every 14th day from a physiotherapist during six months. After the six months of supervised exercise therapy, the SET and HET patients are recommended to continue the same muscle exercise therapy at home, but without feedback, between seven and 12 months. The patients are followed by a blinded observer (physiotherapist unaware of the patient´s randomized group) at three, six and 12 months.