Number of days required to estimate physical activity constructs objectively measured in different age groups: Findings from three Brazilian (Pelotas) population-based birth cohorts

Abstract

The present study aims to estimate the minimum number of accelerometer measurement days needed to estimate habitual physical activity (PA) among 6-(2010), 18-(2011) and 30-(2012) year-old participants, belonging to three population-based Brazilian birth cohorts. Method PA was assessed by triaxial wrist-worn GENEActiv accelerometers and the present analysis is restricted to participants with at least 6 consecutive days of measurement. Accelerometer raw data were analyzed with R-package GGIR. Description of PA measures (overall PA, moderate-to-vigorous PA (MVPA), light PA (LPA)) on weekdays and weekend days were conducted, and statistical differences were tested with chi-squared and Kruskal-Wallis tests. Spearman Brown Formulae was applied to test reliability of different number of days of accelerometer use. Results Differences between week and weekend days regarding LPA, MVPA and overall PA, were only observed among 30-year-olds. Higher levels of MVPA (p = 0.006) and overall PA (p<0.001) were identified on weekdays. For overall PA, to achieve a reliability coefficient >0.70, two and three days of measurement were needed in adults and children, respectively. For LPA, a reliability coefficient >0.70 was achieved with five days in 6-year-old children, three days in 18-year-old young adults, and four days in 30-year-old adults.

Is adherence to the 24-hour movement guidelines associated with a reduced risk of adiposity among children and adolescents?

“…The day cycle was determined using the "from waking up to waking up the next day" approach, which means that a full night of sleep is included in a day cycle and that the duration of a day cycle may vary. Participants were excluded if they had fewer than three weekdays and one weekend day of valid wear (defined as ≥ 16 h per day), or if wear data for each 15-min period in the 24-h cycle were not available [34].…”

Effectiveness and cost-effectiveness of the GoActive intervention to increase physical activity among UK adolescents: A cluster randomised controlled trial

“…Participants who met the inclusion criteria for average daily MVPA were included in any analyses for which they had sufficient data (�2 days) [17]. As the criteria for deriving average daily MVPA did not require both weekend and weekdays of valid data [33], participant numbers varied by outcome.…”

Association between device-measured physical activity and lumbar Modic changes

“…It can also be speculated whether a two-week period is truly representative of a person's average activity level. However, earlier studies have indicated that monitoring of three to 7 days provides reliable estimates of PA behavior [42,[46][47][48][49]. Furthermore, an individual's level of PA is assumed to be quite a stabile trait, meaning that the individuals who were physically active at the time of the study will presumably stay active during other periods of life [50].…”

“…Lumbar MR images of the included participants were obtained by the staff of the department of radiology, Oulu University Hospital, using 1.5-T MRI (Signa HDxt, General Electric, Milwaukee, WI) in 2012-2014 (participants aged [46][47][48]. The imaging was performed by T2weighted fast-recovery fast spin-echo (frFSE) images in the sagittal (repetition time/effective echo time (TR/ effTE) 3500/112 ms, 4 averages, field-of-view (FOV) 280 × 280 mm, acquisition matrix 448 × 224, slice thickness 3 mm with 1 mm interslice gap) and transverse planes (TR/effTE 3600/118 ms, 4 averages, FOV 180 × 180 mm, acquisition matrix 256 × 224, slice thickness 4 mm with 1 mm interslice gap) and T1-weighed fluidattenuated inversion recovery sequence images in the sagittal plane (TR/effTE 860/20 ms, inversion time (TI) of 1969 ms, 1.5 averages, FOV 280 × 280 mm, acquisition matrix 256 × 224, slice thickness 3 mm, interslice gap 4 mm).…”