1. H van den Berg-Emons, PhD (Health Science), is Research Scientist, Institute of Rehabilitation Medicine, Faculty of Medicine and Health Sciences, Erasmus University Rotterdam, Dr Molewaterplein 40, 3015 GD Rotterdam, the Netherlands.
2. J Bussmann, PhD (Medicine and Health Science), BSc (PT), is Research Scientist, Institute of Rehabilitation Medicine, Faculty of Medicine and Health Sciences, Erasmus University Rotterdam
3. A Balk, PhD (Cardiology), MD, is Cardiologist, Thoraxcenter, University Hospital Rotterdam
4. D Keijzer-Oster is a graduate student in medical science at Erasmus University Rotterdam
5. H Stam, PhD (Medicine and Health Science), MD (Medicine and Health Science), is Professor and Director, Institute of Rehabilitation Medicine, Erasmus University Rotterdam, and Department of Rehabilitation, University Hospital Rotterdam