title: Measuring physical activity change in broad-reach intervention trials.
abstract: BACKGROUND
  We compared the responsiveness to change (prepost intervention) of 3 commonly-used self-report measures of physical activity.
  
  
  METHODS
  In a cluster-randomized trial of a telephone-delivered intervention with primary care patients, physical activity was assessed at baseline and 4 months (n = 381) using the 31-item CHAMPS questionnaire; the 6-item Active Australia Questionnaire (AAQ); and, 2 walking for exercise items from the US National Health Interview Survey (USNHIS). Responsiveness to change was calculated for frequency (sessions/week) and duration (MET x minutes/week) of walking and moderate-to-vigorous intensity physical activity.
  
  
  RESULTS
  The greatest responsiveness for walking frequency was found with the USNHIS (0.45, 95% CI: 0.19, 0.72) and AAQ (0.43, 95% CI: 0.19, 0.67), and for walking duration with the USNHIS (0.27, 95% CI 0.13, 0.41) and CHAMPS (0.24, 95% CI: 0.12, 0.36). For moderate-to-vigorous activity, responsiveness for frequency was slightly higher for the AAQ (0.50, 95% CI: 0.30, 0.69); for duration it was slightly higher for CHAMPS (0.32, 95% CI: 0.17, 0.47).
  
  
  CONCLUSIONS
  In broad-reach trials, brief self-report measures (USNHIS and AAQ) are useful for their comparability to population physical activity estimates and low respondent burden. These measures can be used without a loss in responsiveness to change relative to a more detailed self-report measure (CHAMPS).
authors.affiliation: Cancer Prevention Research Centre, University of Queensland, Brisbane, Australia.
authors.forename: Marina M
authors.initials: MM
authors.lastname: Reeves
authors.forename: Alison L
authors.initials: AL
authors.lastname: Marshall
authors.forename: Neville
authors.initials: N
authors.lastname: Owen
authors.forename: Elisabeth A H
authors.initials: EA
authors.lastname: Winkler
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Eakin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016000:Cluster Analysis; D016001:Confidence Intervals; D003625:Data Collection; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009043:Motor Activity; D009749:Nutrition Surveys; D009752:Nutritional Status; D016730:Program Development; D015397:Program Evaluation; D011793:Queensland; D011795:Surveys and Questionnaires; D013997:Time Factors