[1] Royal Netherlands Army, Training Med & Training Physiol Team, Occupat Hlth & Safety Serv, NL-3509 AA Utrecht, Netherlands
[2] Maastricht Univ, Dept Epidemiol, Maastricht, Netherlands
[3] Maastricht Univ, Caphri Res Inst, Maastricht, Netherlands
[4] Univ Sydney, Sch Physiotherapy, Lidcombe, Australia
[5] Back Ctr Copenhagen, Copenhagen, Denmark
[6] New England Baptist Hosp, Spine Ctr, Boston, MA USA
[7] Liberty Mutual Ctr Safety, Ctr Disabil Res, Hopkinton, MA USA