title: In musculoskeletal epidemiology are we asking the unanswerable in questionnaires on physical load?
authors.forename: A
authors.initials: A
authors.lastname: Burdorf
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Beek
mesh_terms: D016021:Epidemiologic Studies; D006801:Humans; D007587:Job Description; D009140:Musculoskeletal Diseases / Q000453:epidemiology* / Q000209:etiology; D009784:Occupational Diseases / Q000453:epidemiology* / Q000209:etiology; D015203:Reproducibility of Results; D012307:Risk Factors; D011795:Surveys and Questionnaires / Q000592:standards*; D016526:Workload