Background: Good quality measures of Japanese adults' sedentary behaviors are needed to accurately assess correlates of specific sedentary behaviors. The present study assessed criterion validity of total sedentary behavior and test-retest reliability of six domain-specific sedentary behaviors.
Methods: We administered a questionnaire, based on previous studies, that measured domain-specific sedentary behaviors. To examine validity, agreement between self-reported time spent in sedentary behaviors from the questionnaire and objectively-measured sedentary time using accelerometers was compared among 392 adults (aged 40-64 years) in two Japanese cities. For reliability, a 2-week interval test-retest was administered to a convenience sample of 34 participants.
Results: The correlation between total self-reported and objectively measured sedentary time was significant (all P < 0.001) and fair-to-good for workdays (ρ = 0.57) and whole week (ρ = 0.49), but was low for non-workdays (ρ = 0.23). The difference between the two measures was significant for whole week (z = -2.25, P = 0.03) and non-workdays (z = -5.50, P < 0.001), but was not significant for workdays (z = -0.60, P = 0.55). There was a significant positive association between the difference in the two measures and the average of these two measures (workdays: r = 0.53; non-workdays: r = 0.45; and whole week: r = 0.54, all P < 0.001). There was fair-to-good test-retest reliability of total sedentary time for each domain (workdays: interclass correlation coefficient [ICC] = 0.77, non-workdays: ICC = 0.53, and whole week: ICC = 0.7; all P < 0.01).
Conclusions: The scale of domain-specific sedentary behaviors is reliable for estimating where and for what purpose Japanese adults spend their sedentary time, and total sedentary time is valid for workdays and the whole week.
Keywords: accelerometer; domain-specific sedentary behavior; measurement; population; questionnaire.