Determinant factors of sedentary time in individuals with COPD

<bold>Background:</bold> The factors influencing sedentary time (ST) of individuals with chronic obstructive pulmonary disease (COPD) have not been thoroughly explored. <bold>Aim:</bold> To identify determinant factors of ST in individuals with COPD. <bold>Methods:</bold> Individuals with moderate to very severe COPD had their ST and variables of physical activity (PA) cross-sectionally assessed during seven days with an activity monitor. Main assessment variables were ST/day (<1.5 METs), time/day in light PA (1.5 to 3 METs), time/day in moderate-to-vigorous PA (MVPA, >3 METs) and steps/day. Other assessments included clinical and sociodemographic data, lung function and body composition (electrical bioimpedance). Multiple linear regression models were built with variables which correlated significantly with ST/day. <bold>Results:</bold> 50 individuals were analyzed (44% males; 66±8 years; FEV1 50±19 %pred). ST was 492±165 minutes/day (61±14 % of the day); time/day in light PA corresponded to 38±14 % and MVPA to 1±1 % of the day. Fat-free mass index (FFMI), steps/day and time/day in light PA correlated with ST in minutes/day (r = −0.25, −0.38 and −0.92, respectively) and with ST expressed as % of the day (r = −0.37, −0.57 and −0.99, respectively). In the multiple regression analyses, variables explaining the variance of ST in minutes/day were steps/day (16%) and light PA (31%) (model R² =. 474, p<0.001) and of ST as % of the day were FFMI (12%), steps/day (32%) and light PA (55%) (model R² =. 994, p<0.001). <bold>Conclusion:</bold> In individuals with COPD, the variance in sedentary time can be explained by fat-free mass, step count and especially time/day in light PA, which reinforces the concept to increase light PA (rather than MVPA) as a strategy to reduce sedentary behavior.