1. Back in Motion Research Group, Department of Orthopaedics, Institute of Clinical Sciences, University of Gothenburg, Mölndal Hospital, Göteborgsvägen 31, 431 80 Mölndal, Gothenburg, 41326 Sweden
2. Division of Physiotherapy, Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg
3. Department of Epidemiology and Biostatistics, Amsterdam Public Health Research Institute, VU University Medical Center, Amsterdam, the Netherlands
4. Department of Rehabilitation Medicine, Research School of CAPHRI, Maastricht University, Maastricht, the Netherlands; and CIR Revalidatie, Eindhoven, the Netherlands
5. Division of Physiotherapy, Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg; Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden; and Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet, Stockholm, Sweden