The multicomponent workplace-based intervention was effective in reducing sitting time, prolonged sitting periods and body fat percentage, and in increasing the number of sit-to-stand transitions.

BackgroundAccelerometers can obtain precise measurements of movements during the day. However, the individual activity pattern varies from day-to-day and there is limited evidence on measurement days needed to obtain sufficient reliability. The aim of this study was to examine variability in accelerometer derived data on sedentary behaviour and physical activity at work and in leisure-time during week days among Danish office employees.MethodsWe included control participants (n = 135) from the Take a Stand! Intervention; a cluster randomized controlled trial conducted in 19 offices. Sitting time and physical activity were measured using an ActiGraph GT3X+ fixed on the thigh and data were processed using Acti4 software. Variability was examined for sitting time, standing time, steps and time spent in moderate-to-vigorous physical activity (MVPA) per day by multilevel mixed linear regression modelling.ResultsResults of this study showed that the number of days needed to obtain a reliability of 80% when measuring sitting time was 4.7 days for work and 5.5 days for leisure time. For physical activity at work, 4.0 days and 4.2 days were required to measure steps and MVPA, respectively. During leisure time, more monitoring time was needed to reliably estimate physical activity (6.8 days for steps and 5.8 days for MVPA).ConclusionsThe number of measurement days needed to reliably estimate activity patterns was greater for leisure time than for work time. The domain specific variability is of great importance to researchers and health promotion workers planning to use objective measures of sedentary behaviour and physical activity.Trial registrationClinical trials NCT01996176.

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BackgroundUsing self-reported surveys to monitor physical activity levels in the population require short items covering both time and intensity. The present study aims to 1) develop the Nordic Physical Activity Questionnaire-short from the original version of the NPAQ, 2) assess test-retest reliability and criterion validity of the NPAQ-short, and 3) test the NPAQ-short’s ability to monitor compliance with the WHO recommendations on physical activity. In addition, we aimed to compare open and closed-ended answering modes for the NPAQ-short.MethodsA sample of 122 participants were included. The NPAQ-short comprised of two questions on weekly moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA). It was filled in twice, two weeks apart, in open- and closed-ended versions. Physical activity was measured objectively by an Actiheart accelerometer worn 24 h/day seven consecutive days. Spearman’s rank correlation and Cohen’s kappa were used to assess correlations between the test and retest results, and between the objective and the self-reported measures.ResultsValid data was available for 92 participants. Test-retest reliability showed Spearman’s rho = 0.82 for MVPA and 0.80 for VPA. For the open-ended questions, the correlations between self-reported and objectively measured physical activity levels were Spearman’s rho = 0.33 for MVPA and rho = 0.32 for VPA. For closed-ended questions, the kappa-coefficients were 0.17 for MVPA and 0.21 for VPA. When using objective and self-reported measures to monitor WHO’s physical activity recommendations, the kappa correlations were 0.42 for open-ended and 0.34 for closed-ended answering modes.ConclusionThe NPAQ-short was found to be sufficiently reliable and valid to monitor physical activity levels in the population when using both open and closed-ended questions. However, using open-ended questions seems to be a better answering mode for self-reported surveys monitoring WHO’s physical activity recommendations.Electronic supplementary materialThe online version of this article (10.1186/s12889-018-5538-y) contains supplementary material, which is available to authorized users.

The purpose was to examine and compare the effects of replacing time spent sitting with standing at work on fat-free mass, fat mass and waist circumference using isotemporal substitution. Analyses were conducted on work hours on both cross-sectional and longitudinal data. The study included 223 persons from an intervention study aimed at reducing sitting time at work among office employees. Sitting, standing and anthropometry were measured objectively. Cross-sectional isotemporal substitution analyses were modelled on baseline data, while longitudinal analyses were modelled based on differences in sitting and standing time at work between baseline and 1-month follow-up in relation to differences in anthropometric measures between baseline and 3-months follow-up. Replacing one hour of sitting time with one hour of standing was associated with a 0.21 kg higher fat-free mass in the longitudinal analysis and 0.95 kg in the cross-sectional analysis. Fat mass was 0.32 kg lower in the longitudinal analysis and 0.61 kg lower in the cross-sectional analysis. Waist circumference decreased by 0.38 cm in the longitudinal analysis and 0.81 cm in the cross-sectional analysis. Both cross-sectional and longitudinal analyses showed an effect on body composition measures by replacing one hour of sitting with standing however, this effect was largest in the cross-sectional analyses.Trial registration ClinicalTrials.gov NCT01996176.