Occupational sedentary time and associations with adipositymarkers : a quantile regression analysis

Background: Sedentary behaviour is associated with a number of health related outcomes, independent of physical activity; however, there is limited research that has examined the role that occupational sedentary time contributes to these associations. For those who are economically active, the majority of their sedentary time may be accrued in the workplace. The aim of this study was to examine the associations of occupational sedentary time with waist circumference (WC) and body mass index (BMI). Methods: Data were taken from the Health Survey for England, a nationally representative annual survey of adults. In 2008, a subsample wore an ActiGraph GT1M accelerometer for 7 days; non-wear time was removed using the Troiano algorithm, and time in occupational sedentary behaviour was extracted using previously derived cut-points. To examine the variable effects of sedentary time on WC and BMI, quantile regression models were used; models were adjusted for age, gender, accelerometer wear-time, lifestyle variables, health status, non-work sedentary time and time in moderate to vigorous physical activity (MVPA). Results: From the accelerometer subsample, 911 were in full-time employment. Occupational sedentary time was not associated with either WC or BMI across quantiles of these adiposity markers, after regression models were adjusted for MVPA: for each 1 minute increase per day in MVPA there were significant associations with reduced WC, and this effect varied with increasing quantiles of WC (β coefficients for the 25th, 50th, 75th quantiles were −0.045, −0.065, −0.101). Conclusion: Associations between occupational sedentary time and adiposity markers can be explained by MVPA.