Physical activity questionnaires : A critical review of methods used in validity and reproducibility studies

Aim. The purpose of this paper was to investigate physical activity questionnaires, and to examine studies of their reliability and validity, focusing on the variable frequency. The research questions were following: 1. What are the methods and the results of the investigated questionnaires’ validity and reproducibility studies? 2. How is the frequency of physical activity assessed and validated in different PA questionnaires? Method. The 16 (out of 24) first questionnaires concerning individuals from 18-69 years were selected from a collection of physical activity questionnaires. The topical International Physical Activity Questionnaire (IPAQ), both the long and the short version were also included in the investigation. Additional searches for articles were done in PubMed. Information about the design of the in total 18 questionnaires were structured in a scheme toclarify similarities and differences. How the frequency of physical activity (PA) was assessed was of particular interest. To evaluate methods and statistics the first validity and reliability study from each questionnaire’s reference list was selected and reviewed. This based on certain statistical criteria, regarding within-subject variation, test-retest, changes of mean, linear regression analysis, and criterion/construct methods for the validation. Results. The common approach is to compute correlation coefficients (n=18). One validity study out of 18 investigates systematic changes. No study presents results of changes of mean. In many studies, within-subject variation is calculated (n=14). Common validity measures areVO2 max (n=8), PA record (n=7), accelerometer (n=9) and to validate the questionnaire against other questionnaires (n=7). The correlation coefficient is at best r =0.30. Direct assessment of accuracy of reported frequency of PA was not measured in any study. One questionnaire assesses seasonal variations of physical activity. Conclusions. The accuracy of the investigated PA questionnaires is low. There are areas for improvements in the construct and administration of PA questionnaires, and the assessment of PA will need a combination of measurement instruments to cover all aspects of PA. Reliability and validity studies must focus on detecting the order effect and the systematic error of the questionnaire. Until then interpretations of reported physical activity data will be misleading. Current physical activity recommendations may have to be redesigned