title: Comparison of energy expenditure estimates from doubly labeled water, a physical activity questionnaire, and physical activity records.
abstract: BACKGROUND
  Various methods are used by epidemiologists to estimate the energy cost of physical activity; these include physical activity records and recalls. However, there is limited validation of these methods against the doubly labeled water technique for determining energy expenditure (EE).
  
  
  OBJECTIVE
  We compared EE as estimated by indirect methods (physical activity records and recall questionnaires) used in epidemiologic studies with EE obtained from doubly labeled water (EE(DLW)) in free-living men.
  
  
  METHODS
  We determined EE(DLW), energy intake at weight maintenance, and EE from 7-d physical activity records (EE(Record)) and a 7-d physical activity recall questionnaire (EE(Recall)) in 24 men aged 41 plus minus 2.0 y ( plus minus SEM) with a body mass index (in kg/m(2)) of 25.1 plus minus 0.5.
  
  
  RESULTS
  There was excellent agreement between EE(DLW) (13.27 plus minus 0.35 MJ/d) and energy intake (13.19 plus minus 0.36 MJ/d), with a difference of 0.5 plus minus 1.0% ( plus minus SE). The indirect measures of physical activity and EE were 14.17 plus minus 0.37 MJ/d for EE(Record) (difference from EE(DLW): 7.9 plus minus 3.2%) and 17.40 plus minus 1.45 MJ/d for EE(Recall) (difference from EE(DLW): 30.6 plus minus 9.9%).
  
  
  CONCLUSIONS
  Seven-day physical activity records provide an acceptable estimate of EE in free-living adults compared with EE(DLW), but 7-d physical activity recalls have limited application to estimate daily EE. For optimal validity, the 7-d physical activity records require good subject compliance and the provision of careful instructions for their use.
authors.affiliation: US Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet and Human Performance Laboratory, Beltsville, MD 20705, USA. conway@bhnrc.arsusda.gov
authors.forename: Joan M
authors.initials: JM
authors.lastname: Conway
authors.forename: James L
authors.initials: JL
authors.lastname: Seale
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Irwin
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Ainsworth
mesh_terms: D000328:Adult; D000368:Aged; D001481:Basal Metabolism / Q000502:physiology; D001823:Body Composition / Q000502:physiology; D015992:Body Mass Index; D002153:Calorimetry, Indirect; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D010349:Patient Compliance; D011865:Radioisotope Dilution Technique; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires