From Sedentary Time to Sedentary Patterns: Accelerometer Data Reduction Decisions in Youth

Abstract

AimThis study aims to establish evidence-based accelerometer data reduction criteria to accurately assess total sedentary time and sedentary patterns in children.MethodsParticipants (n = 1057 European children; 9–13 yrs) were invited to wear an accelerometer for at least 6 consecutive days. We explored 1) non-wear time criteria; 2) minimum daily valid wear time; 3) differences between weekday and weekend day; and 4) minimum number of days of accelerometer wear by comparing the effects of commonly used data reduction decisions on total sedentary time, and duration and number of prolonged sedentary bouts.ResultsMore than 60 consecutive minutes of zero counts was the optimal criterion for non-wear time. Increasing the definition of a valid day from 8 to 10 hours wear time hardly influenced the sedentary outcomes, while the sample size of children with more than 4 valid days increased from 69 to 81%. On weekdays, children had on average 1 hour more wear time, 50 minutes more total sedentary time, 26 minutes more sedentary time accumulated in bouts, and 1 more sedentary bout. At least 6 days of accelerometer data were needed to accurately represent weekly sedentary time and patterns.ConclusionsBased on our results we recommend 1) a minimum of 60 minutes of consecutive zeros as the most realistic criterion for non-wear time; and 2) including at least six days with minimum eight valid hours to characterize children's usual total sedentary time and patterns, preferably including one weekend day.

Middle School Students’ Free-living Physical Activity on Physical Education Days, Non-physical Education Days, and Weekends

“…To achieve reliability of 0.80 or better, Trost et al, (2005) suggest that four to five days of monitoring is necessary to calculate physical activity levels, other studies also suggest four days of monitoring (Tudor-Locke et al, 2009). Complete days were considered only if there were 10 or more hours of recorded data per day (Chinapaw et al, 2014). Studies showed a high reliability (r=0.86), and sample size could be achieved when children with < two days lasting <10 hours/day were included in analyses (Rich et al, 2013).…”

Occurrence and duration of various operational definitions of sedentary bouts and cross-sectional associations with cardiometabolic health indicators: The ENERGY-project

“…For details see elsewhere (Yildirim et al, 2011). After applying evidence-based data reduction procedures (Chinapaw et al, 2014), we had valid accelerometer data of 647 children. Anthropometrics were collected for all children participating in the accelerometer study from all five countries, but only children from Hungary and the Netherlands who participated in the accelerometer study were asked to provide blood samples.…”

“…For inclusion in the data analysis, each participant needed a minimum of six days with at least eight valid hours, including at least one weekend day. Periods of more than 60 min of consecutive zero counts were defined as non-wear time and excluded from data analysis (Chinapaw et al, 2014). We selected a cut-point of b 100 cpm to define sedentary time (Trost et al, 2011;Fischer et al, 2012).…”

Sedentary behaviour and health in children — Evaluating the evidence

“…Objective measures derived from accelerometers and inclinometers are an important step forward when examining the effect of sedentary time but cannot yet distinguish specific sedentary activities such as watching TV, use of computers or tablets, and reading. Furthermore, there is no evidence-based standard protocol for the subjective decisions involved in accelerometer data reduction (Chinapaw et al, 2014) or analysis regarding sedentary time as yet. This is a major barrier towards finding the true association and makes comparison between published studies difficult, if not impossible.…”