Number of Days Required to Estimate Habitual Activity Using Wrist-Worn GENEActiv Accelerometer: A Cross-Sectional Study

Abstract

IntroductionObjective methods like accelerometers are feasible for large studies and may quantify variability in day-to-day physical activity better than self-report. The variability between days suggests that day of the week cannot be ignored in the design and analysis of physical activity studies. The purpose of this paper is to investigate the optimal number of days needed to obtain reliable estimates of weekly habitual physical activity using the wrist-worn GENEActiv accelerometer.MethodsData are from a subsample of the Mitchelstown cohort; 475 (44.6% males; mean aged 59.6±5.5 years) middle-aged Irish adults. Participants wore the wrist GENEActiv accelerometer for 7-consecutive days. Data were collected at 100Hz and summarised into a signal magnitude vector using 60s epochs. Each time interval was categorised according to intensity based on validated cut-offs. Spearman pairwise correlations determined the association between days of the week. Repeated measures ANOVA examined differences in average minutes across days. Intraclass correlations examined the proportion of variability between days, and Spearman-Brown formula estimated intra-class reliability coefficient associated with combinations of 1–7 days.ResultsThree hundred and ninety-seven adults (59.7±5.5yrs) had valid accelerometer data. Overall, men were most sedentary on weekends while women spent more time in sedentary behaviour on Sunday through Tuesday. Post hoc analysis found sedentary behaviour and light activity levels on Sunday to differ to all other days in the week. Analysis revealed greater than 1 day monitoring is necessary to achieve acceptable reliability. Monitoring frame duration for reliable estimates varied across intensity categories, (sedentary (3 days), light (2 days), moderate (2 days) and vigorous activity (6 days) and MVPA (2 days)).ConclusionThese findings provide knowledge into the behavioural variability in weekly activity patterns of middle-aged adults. Since Sunday differed from all other days in the week this suggests that day of the week cannot be overlooked in the design and analysis of physical activity studies and thus should be included in the study monitoring frames. Collectively our data suggest that six days monitoring, inclusive of Saturday and Sunday, are needed to reliably capture weekly habitual activity in all activity intensities using the wrist-worn GENEActiv accelerometer.

Relationships between muscle size, strength, and physical activity in adults with muscular dystrophy

“…Wrist‐worn accelerometers have previously been recommended as the best location for accelerometers for wheelchair users, as well as removing any issues of access and comfort that would be associated with other locations (such as mid‐thigh or waist). Monitors were worn for 24 h a day on the preferred wrist of participants and worn continuously for 7 days . Monitors were initialized to collect data at 100 Hz and acceleration values, recorded in g, and recorded continuously on each axis (x, y, and z).…”

“…Monitors were worn for 24 h a day on the preferred wrist of participants and worn continuously for 7 days. 60 Monitors were initialized to collect data at 100 Hz and acceleration values, recorded in g, and recorded continuously on each axis (x, y, and z). Recorded total activity time has been previously validated against doubly labelled water.…”

Measuring Physical Activity with Hip Accelerometry among U.S. Older Adults: How Many Days Are Enough?

“…As with children and younger adults,[25] older adults are less active on weekends, especially on Sundays. For older adults, accelerometry measures of sedentary behavior (%) and light-lifestyle activity (%) are significantly different on both Saturdays and Sundays compared to weekdays.…”

How many days are needed to estimate accelerometry-assessed physical activity during pregnancy? Methodological analyses based on a cohort study using wrist-worn accelerometer

“…Several studies have been carried out in children [9], young [10,11] and adult population [12,13] focused on the numbers of monitoring days necessary to represent habitual PA behavior. Results of these studies suggested a large variability in the number of days required to obtain reliable measures of PA ranging from 2 to 9 days.…”

“…Results of these studies suggested a large variability in the number of days required to obtain reliable measures of PA ranging from 2 to 9 days. Also, the number of required days varies according to the intensity of physical activities, often grouped as sedentary behavior, and light, moderate, and vigorous intensity [12,13]. Other factors that can influence the monitoring time-frame are the type of accelerometer used and placement of the device (e.g., wrist, thigh, or waist) [6–8].…”