title: Estimation of energy expenditure from physical activity measures: determinants of accuracy.
abstract: OBJECTIVE
  To describe the determinants, specifically age, body mass index, percentage of body fat, and physical activity (PA) level, associated with over- and underestimation of energy expenditure (EE) using PA records and the Stanford Seven-Day Physical Activity Recall (7DR) compared with doubly labeled water (DLW).
  
  
  METHODS
  We collected PA measures on 24 males eating a controlled diet designed to maintain body weight, and we determined EE from DLW and estimated EE from PA records and 7DR.
  
  
  RESULTS
  Absolute differences in the estimation of EE between DLW and PA assessment methods were greater for the 7DR (30.6 +/- 9.9%) than PA records (7.9 +/- 3.2%). In PA records, overestimation of EE was greater with older age and higher body fatness; EE was overestimated by 16.7% among men 50 years and older compared with only 5.3% among men <40 years of age. For percentage of body fat, EE was overestimated by 19.7% among men with a percentage of body fat > or =30% compared with only 5.6% among men with a percentage of body fat <25%. A trend for less overestimation of EE with higher levels of PA (measured by DLW/basal metabolic rate [BMR]) also was observed in the PA records. In the 7DR, the estimates of EE varied widely and no trends were observed by age, percentage of body fat, and PA levels.
  
  
  CONCLUSIONS
  Estimation of EE from the 7DR is considerably more variable than from PA records. Factors related to age and percentage of body fat influenced the accuracy of estimated EE in the PA record. Additional studies are needed to understand factors related to accurate reporting of PA behaviors, which are used to estimate EE in free-living adults.
authors.affiliation: Fred Hutchinson Cancer Research Center, Cancer Prevention Research Program, Seattle, Washington, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Irwin
authors.forename: B E
authors.initials: BE
authors.lastname: Ainsworth
authors.forename: J M
authors.initials: JM
authors.lastname: Conway
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001481:Basal Metabolism; D001823:Body Composition; D015992:Body Mass Index; D001834:Body Water; D015930:Diet Records; D004734:Energy Metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D010809:Physical Fitness; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity