title: Assessment of the physical activity level with two questions: validation with doubly labeled water.
abstract: OBJECTIVE
  To validate a two-question questionnaire on physical activity with the doubly labeled water (DLW) method.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Nine volunteers, age 33-75 years, with a mean body mass index (BMI) (kg m(-2)) of 27.4.
  
  
  METHODS
  A questionnaire with one question on physical activity at work and one question on physical activity during leisure time. The answers were converted into a PAL (physical activity level=energy expenditure/basal metabolic rate) value, which was validated with the DLW method.
  
  
  RESULTS
  The mean values (s.d.) of PAL for the questionnaire and DLW measurements were 1.7 (0.1) and 1.7 (0.1), respectively, with a mean difference of 0.004 (0.172).
  
  
  CONCLUSIONS
  The results were promising to the extent that they could be used in large-scale epidemiological studies.
authors.affiliation: Department of Health Behaviours, The Swedish National Institute of Public Health, Ostersund, Sweden. gunnar.johansson@fhi.se
authors.forename: G
authors.initials: G
authors.lastname: Johansson
authors.forename: K R
authors.initials: KR
authors.lastname: Westerterp
mesh_terms: D000328:Adult; D000368:Aged; D001481:Basal Metabolism / Q000502:physiology; D004651:Employment; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D007899:Leisure Activities; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology*; D011865:Radioisotope Dilution Technique; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires / Q000592:standards*; D014867:Water
chemical_list: D014867:Water