1 Department of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, The Netherlands; Amsterdam Public Health Research Institute, Department of General Practice & Elderly Care Medicine, Vrije Universiteit Amsterdam, The Netherlands; Health care centre, Hoofddorp, The Netherlands.
2 Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
3 Department of Rehabilitation Sciences and Physiotherapy, University of Antwerp, Belgium.
4 Department of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, The Netherlands.