1. Department of Health Sciences, Gerontology Research Center, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
2. School of Health and Social Studies, University of Applied Sciences, Rajakatu 35, 40200 Jyväskylä, Finland
3. Peurunka-Medical Rehabilitation and Physical Exercise Center, Peurungantie 85, 41340 Laukaa, Finland
4. Department of Health Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
5. Department of Orthopedics and Traumatology, Central Finland Central Hospital, Keskussairaalantie 19, 40620 Jyväskylä, Finland
6. Department of Medical Rehabilitation, Oulu University Hospital, P.O. Box 21, 90029 Oulu, Finland