1. Zurich University of Applied Sciences, Winterthur, and Centre on Aging and Mobility, University of Zurich, and City Hospital Waid; Zurich Switzerland
2. Centre on Aging and Mobility, University of Zurich, and City Hospital Waid; Zurich Switzerland
3. Swiss Ankylosing Spondylitis Association; Zurich Switzerland
4. University of Oslo; Oslo Norway
5. University Hospital Zurich and Zurich Rehabilitation Clinic Wald, Cardiology Rehabilitation Wald; Zurich Switzerland
6. University Hospital Zurich; Zurich Switzerland
7. University Hospital Zurich and Centre on Aging and Mobility, University of Zurich, and City Hospital Waid; Zurich Switzerland