International physical activity questionnaire: Reliability and validity in a Spanish population

Although questionnaires are useful for evaluating patterns of physical activity in populations, they need to be validated. The objective of this study was to determine the validity and reliability of the long version of the International Physical Activity Questionnaire (IPAQ) in a Spanish population. The participants wore a uniaxial MTI Actigraph (Computer Science and Application, Inc.) accelerometer for 7 days and self-completed the IPAQ questionnaire twice, to assess its reliability. Criterion validity was assessed by comparing data from the IPAQ and data from the MTI. The final sample included 54 adults for the validity analysis and 66 adults for the reliability analysis. The correlations (r) between the IPAQ and the accelerometer were 0.29 (P <0.05) for total physical activity (MET · min^-1 · day^-1) versus total counts per minute, 0.30 (P <0.05) for time spent in vigorous activity, and 0.34 (P <0.05) for time spent sitting. The IPAQ showed a good reliability coefficient for total physical activity (r=0.82, P <0.05), vigorous activity (r=0.79, P <0.05), moderate activity (r=0.83, P <0.05), and time spent walking (r=0.73, P <0.05). Total time spent on work-related physical activities (r=0.92, P <0.05), on household-related activities (r=0.86, P <0.05), and leisure-time physical activities (excluding walking) (r=0.82, P <0.05) showed good reliability coefficients. Bland Altman analysis showed that discrepancies between the two methods increased with the amount of moderate and vigorous physical activity undertaken. In conclusion, the long version of the IPAQ has acceptable validity for the measurement of total and vigorous physical activity, and good reliability coefficients for application in the Spanish population studied here. The questionnaire showed poor validity for reporting moderate-intensity activity in this Spanish population.