Test-retest repeatability and relative validity of the global physical activity questionnaire in a developing country context

Background: The increasing prevalence of chronic lifestyle diseases in developing countries warrants reliable and valid surveillance of physical activity levels in the population. This study assesses the test-retest repeatability and criterion validity of the WHO-recommended Global Physical Activity Questionnaire (GPAQ) in Vietnamese adults during the dry and wet seasons. Methods: In 2007 a representative sample of 169 adults (25-64 years) was recruited to determine the GPAQ reliability and validity. GPAQ assesses time and intensity of physical activities spent during a usual week. To assess short and long term reliability, participants completed the GPAQ twice during the dry season 2 weeks apart and again 2 months later during the wet season. For validation purposes, participants wore an accelerometer during the 7 days before the first and last GPAQ assessments. Results: The total GPAQ score showed repeatability correlations of 0.69 after 2 weeks and of 0.55 after 2 months. Total GPAQ score and accelerometer data showed validity correlations of 0.34 and 0.20 in the dry and wet season, respectively. There was a difference in physical activity patterns between the dry and wet seasons. Conclusions: GPAQ is suitable for surveillance of physical activity among adults in Vietnam.