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Ekelund, U.

Publications and source records attributed to Ekelund, U..

2 recordsLinked to original sources
bioRxiv2019

Number of days required to estimate objectively measured physical activity constructs in different age groups

PurposeThe present study aims to estimate the minimum number of accelerometer measurement days needed to estimate habitual physical activity (PA) among 6, 18 and 30 years old participants, belonging to three population-based Brazilian birth cohorts. Method: PA was assessed by triaxial wrist worn GENEActiv accelerometers for 4-7 consecutive days, including at least one weekend day. Accelerometer raw data were analyzed with R-package GGIR. Description of PA measures (overall PA, MVPA, LPA) between weekdays and weekend days were conducted, and statistical differences were tested with chi-squared and Kruskal-Wallis tests. Intraclass Reliability Coefficient (IRC) was applied through the Spearman Brown Formulae 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. More MVPA (p=0.006) and Overall PA (p<0.001) were performed on week days. The IRC coefficients ranged from 0.44 to 0.83 in children and from 0.54 to 0.88 in adults. Conclusion: In conclusion, our results show that between four and six measurement days are needed to achieve good reliability in the analyzed participants, depending on the PA construct evaluated (MVPA, LPA or overall PA).

epidemiology↗
bioRxiv2019

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

BackgroundObjective methods to measure physical activity (PA) can lead to better cross-cultural comparisons, monitoring temporal PA trends, and measuring the effect of interventions. However, when applying this technology in field-work, the accelerometer data processing is prone to methodological issues. One of the most challenging issues relates to standardizing total wear time to provide reliable data across participants. It is generally accepted that at least 4 complete days of accelerometer wear represent a week for adults. It is not known if this same assumption holds true for pregnant women.\n\nAimWe assessed the optimal number of days needed to obtain reliable estimates of overall PA and moderate-to-vigorous physical activity (MVPA) during pregnancy using a raw triaxial wrist-worn accelerometer.\n\nMethodsCross-sectional analyses were carried out in the antenatal wave of the 2015 Pelotas (Brazil) Birth Cohort Study. Participants wore the wrist ActiGraph wGT3X-BT accelerometer for seven consecutive days. The daily average acceleration, which indicates overall PA, was measured as milli-g (mg), and time spent in MVPA (minutes/day) was analyzed in 5-minute bouts. ANOVA and Kruskal-Wallis tests were used to compare variability across days of the week. Bland-Altman plots and Spearman-Brown Prophecy Formula were applied to determine the reliability coefficient associated with one to seven days of measurement. Analyses were stratified by sociodemographic factors and nutritional status.\n\nResultsAmong 2,082 pregnant women who wore the accelerometer for seven complete days, overall and MVPA were lower on Sundays compared to other days of the week. Reliability of >=0.80 to evaluate overall PA was reached with at least three monitoring days, whereas six days were needed to estimate reliable measures of MVPA.\n\nConclusionsOur findings indicate that the usual approach obtaining one week of accelerometry in adults is also appropriate for pregnant women, particularly to obtain differences on weekend days and reliably estimate MVPA.

epidemiology↗