Criterion Validity and Reliability of the IPAQ-SF for Assessing Sedentary Behavior in Adults Using Different Accelerometer Cut-Off Points

This study aimed to investigate the criterion validity and reliability of the International Physical Activity Questionnaire - Short Form (IPAQ-SF) for estimating sedentary behavior (SB) across different time contexts (weekdays, weekends, and total weekly time) and using different accelerometer cut-off points. A total of 80 university students (73.7% women; mean age 26.0 ± 6.2 years) from a public higher education institution in Bahia, Brazil, participated in this methodological validation study. Sedentary time was objectively measured using an ActiGraph wGT3X-BT accelerometer over seven consecutive days, applying two cut-off points (<100 and <150 counts per minute). Self-reported sitting time was obtained using the IPAQ-SF, and test-retest reliability was assessed in a subsample of 20 participants after 14 days using the intraclass correlation coefficient (ICC). Criterion validity was examined using Spearman's correlation and Bland-Altman analysis. The IPAQ-SF demonstrated moderate to almost perfect reliability (ICC = 0.622-0.856). Criterion validity was weak but statistically significant when using the <150 cpm cut-off for weekdays and total weekly sedentary time. Bland-Altman analysis indicated that the IPAQ-SF underestimated sitting time by 56% (≈214 min/day) at <100 cpm and overestimated it by 17.8% (≈117 min/day) at <150 cpm. Correlations were stronger for weekdays than weekends. In conclusion, the IPAQ-SF showed excellent reproducibility but limited criterion validity, highlighting the need for cautious interpretation of self-reported sedentary behavior in population-based studies.