Work for third parties: Cochrane Musculoskeletal group, Ottawa (p. Tugwell), Cochrane Back Group, Toronto (L. Bouter, C. Bombardier), Folkehelse, National institute for public health (K. Hagen), Centre for Evidence-Based Physiotherapy, Sydney (C. Maher, R. Herbert, A. Mosel, Cochrane Back Group, Toronto (L. Bouter, C. Bombardier), Folkehelse, National institute for public health (K. Hagen), Centre for Evidence-Based Physiotherapy, Sydney (C. Maher, R. Herbert, A. Moseley), Rivermead Rehabilitation Centre, Oxford (D. Wade), Physiotherapy Wissenschaften Program, University of Zurich (K. Niedermann, E. Huber), MAS Sports Physiotherapy Program, University of Salzburg (E. Hogenbirk)