[1] Arteveldehogesch, Physiotherapy Dept, B-9000 Ghent, Belgium
[2] Katholieke Univ Leuven, Dept Rehabil Sci, Fac Phys Educ & Physiotherapy, B-3000 Louvain, Belgium
[3] Katholieke Univ Leuven, Fac Med, Ctr Dev Disabil, B-3000 Louvain, Belgium
[4] Univ Nijmegen, NL-6511 PS Nijmegen, Netherlands
[5] Univ Profess, NL-4811 GS Breda, Netherlands