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Adequately measuring physical activity (PA) is important for determining trends in PA levels over time, for evaluation of the effect of PA interventions and for determining health benefits of PA. Poor measurement of PA may hinder detection of important associations or effects.[1] Many questionnaires have been developed to measure PA. Some questionnaires were developed specifically for a certain subgroup or setting, others because researchers were not aware of existing questionnaires or because they were not satisfied with available questionnaires. Often researchers needed to translate and/or adapt existing questionnaires to other target groups. This has led to a large number of (versions of) questionnaires available, which makes it difficult to choose the most suitable instrument. Furthermore, the use of different instruments in different studies and surveys makes comparison of PA levels across countries or studies difficult.
To our knowledge, an overview of the measurement properties of PA questionnaires is lacking. A summary of these findings might be helpful for choosing the best questionnaire available for a specific purpose. Furthermore, a critical assessment of the methodological quality of the studies assessing the measurement properties of PA questionnaires is lacking, while the methodological quality of these studies might be variable. If the methodological quality of a study is poor, the results and conclusions can be seriously biased. For example, wrong conclusions can be drawn from a validation study if no adequate comparison instrument was used. It is therefore important to assess the methodological quality of a study to be confident that the design, conduct, analysis and interpretation of the study is adequate, and to inform about possible bias that might have influenced the results.
In this article, we aim to evaluate and compare the measurement properties of all available self-administered questionnaires measuring PA in adults, using a systematic approach for the literature search, data extraction and assessment of the quality of the studies. This article is one of a series of four articles on measurement properties of PA questionnaires published in Sports Medicine.
1. Methods
1.1 Literature Search
Literature searches were performed in PubMed, EMBASE using 'EMBASE only', and in SportDiscus® (complete databases until May 2009) on the topic of self-report questionnaires of PA. Additional papers were identified by manually searching references of the retrieved papers...