Validity and reproducibility of self-reported total physical activity—differences by relative weight

OBJECTIVE: Physical activity is hypothesized to reduce the risk of obesity and several other chronic diseases and enhance longevity. However, most of the questionnaires used measure only part of total physical activity, occupational and/or leisure-time activity, which might lead to misclassification of total physical activity level and to dilution of risk estimates. We evaluated the validity and reproducibility of a short self-administered physical activity questionnaire, intended to measure long-term total daily 24 h physical activity.