Past-day recall of sedentary time: Validity of a self-reported measure of sedentary time in a university population

Objectives: To assess the validity of the Past-day Adults' Sedentary Time-University (PAST-U) questionnaire, modified for a university population, compared with activPAL. 

Design: Participants (= 57, age = 18-55 years, 47% female, 65% students) were recruited from the University of Queensland (students and staff). 

Methods: Participants answered the PAST-questionnaire, which asked about time spent sitting or lying down for work, study, travel, television viewing, leisure-time computer use, reading, eating, socialising and other purposes, during the previous day. Times reported for these questions were summed to provide a measure of total sedentary time. Participants also wore an activPAL device for the full day prior to completing the questionnaire and recorded their wake and sleep times in an activity log. Total waking sedentary time derived from the activPAL was used as the criterion measure. Correlation (intraclass correlation coefficient, ICC) and agreement (Bland-Altman plots) between PAST-and activPAL sedentary time were examined. 

Results: Participants were sedentary (activPAL-determined) for 66% of waking hours. The correlation between PAST-and activPAL sedentary time for the whole sample was ICC = 0.64 [95% confidence interval (CI) = 0.45, 0.77]; and higher for non-students (ICC = 0.78, 95%CI 0.52, 0.91) than students (ICC = 0.59, 95%CI 0.33, 0.77). Bland-Altman plots revealed that the mean difference between the two measures was 5 min although limits of agreement were wide (95% limits of agreement: -3.9 to 4.1 h). 

Conclusions: The PAST-provides an acceptable measure of sedentary time in this population, which included students and adults with high workplace sitting time.