Objective: Little is known about the influence of age, gender and language on the measurement properties of the long International Physical Activity Questionnaire (IPAQ). The aim was to validate the long IPAQ in adults aged 18-84 in the German-, French- and Italian-speaking parts of Switzerland, focusing on differences between gender, age groups and language regions.
Methods: This cross-sectional study was conducted in the frame of SAPALDIA (Swiss Cohort Study on Air Pollution and Lung and Heart Disease in Adults) in 2011. 346 participants (54.6% women, mean age 54.6 years) wore an Actigraph GT3X accelerometer during 8 days and completed the IPAQ. IPAQ and accelerometer data on total physical activity and on different intensities as well as sitting time were compared using Spearman correlations and Bland-Altman plots.
Results: Correlations were highest for vigorous physical activity (r = 0.41) and sitting time (r = 0.42). Significant gender differences were apparent for leisure-time physical activity (men: r = 0.35 versus women: r = 0.57, p = 0.012) and for sitting time (men: r = 0.28 versus women: r = 0.53, p = 0.007). Differences between age groups were present for sitting time (youngest: r = 0.72 versus middle: r = 0.36, p < 0.001; youngest versus oldest: r = 0.34, p = 0.001). Differences between language regions were present for vigorous physical activity (German: r = 0.28 versus Italian: r = 0.53, p = 0.033). IPAQ overestimated physical activity but underestimated sitting time.
Conclusion: The long IPAQ showed moderate validity similar to other studies when compared to accelerometer data in a diverse sample of individuals. Some sex, age and regional differences were observed but do not seem to limit its applicability in population sub groups.
Keywords: Adults; Measurement properties; Self-report physical activity; Validity.