title: Validation of the historical adulthood physical activity questionnaire (HAPAQ) against objective measurements of physical activity.
abstract: BACKGROUND
  Lifetime physical activity energy expenditure (PAEE) is an important determinant of risk for many chronic diseases but remains challenging to measure. Previously reported historical physical activity (PA) questionnaires appear to be reliable, but their validity is less well established.
  
  
  METHODS
  We sought to design and validate an historical adulthood PA questionnaire (HAPAQ) against objective PA measurements from the same individuals. We recruited from a population-based cohort in Cambridgeshire, UK, (Medical Research Council Ely Study) in whom PA measurements, using individually calibrated heart rate monitoring, had been obtained in the past, once between 1994 and 1996 and once between 2000 and 2002. 100 individuals from this cohort attended for interview. Historical PA within the domains of home, work, transport, sport and exercise was recalled using the questionnaire by asking closed questions repeated for several discrete time periods from the age of 20 years old to their current age. The average PAEE from the 2 periods of objective measurements was compared to the self-reported data from the corresponding time periods in the questionnaire.
  
  
  RESULTS
  Significant correlations were observed between HAPAQ-derived and objectively measured total PAEE for both time periods (Spearman r = 0.44; P < 0.001). Similarly, self-reported time spent in vigorous PA was significantly correlated with objective measurements of vigorous PA (Spearman r = 0.40; P < 0.001).
  
  
  CONCLUSIONS
  HAPAQ demonstrates convergent validity for total PAEE and vigorous PA. This instrument will be useful for ranking individuals according to their past PA in studies of chronic disease aetiology, where activity may be an important underlying factor contributing to disease pathogenesis.
authors.affiliation: Medical Research Council Epidemiology Unit, IMS, Cambridge, UK. herve.besson@mrc-epid.cam.ac.uk.
authors.forename: Hervé
authors.initials: H
authors.lastname: Besson
authors.forename: Ceryl A
authors.initials: CA
authors.lastname: Harwood
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.forename: Francis M
authors.initials: FM
authors.lastname: Finucane
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: McDermott
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Shaw
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Wareham