BACKGROUND: Sedentary behavior is regarded as a distinct risk factor for cardiometabolic morbidity and mortality, but knowledge of the efficacy of interventions targeting reductions in sedentary behavior is limited.

PURPOSE: To investigate the effect of an individualized face-to-face motivational counseling intervention aimed at reducing sitting time.

DESIGN: A randomized, controlled, observer-blinded, community-based trial with two parallel groups using open-end randomization with 1:1 allocation.

SETTING/PARTICIPANTS: A total of 166 sedentary adults were consecutively recruited from the population-based Health2010 Study.

INTERVENTION: Participants were randomized to a control (usual lifestyle) or intervention group with four individual theory-based counseling sessions.

MAIN OUTCOME MEASURES: Objectively measured overall sitting time (ActivPAL 3TM, 7 days); secondary measures were breaks in sitting time, anthropometric measures, and cardiometabolic biomarkers, assessed at baseline and after 6 months. Data were collected in 2010-2012 and analyzed in 2013-2014 using repeated measures multiple regression analyses.

RESULTS: Ninety-three participants were randomized to the intervention group and 73 to the control group, and 149 completed the study. The intervention group had a mean sitting time decrease of -0.27 hours/day, corresponding to 2.9% of baseline sitting time (hours/day); the control group increased mean sitting time by 0.06 hours/day. The between-group difference in change, -0.32 hours/day (95% CI=-0.87, 0.24, p=0.26), was not statistically significant. Significant differences in change in fasting serum insulin of -5.9 pmol/L (95% CI=-11.4, -0.5, p=0.03); homeostasis model assessment-estimated insulin resistance of -0.28 (95% CI=-0.53, -0.03, p=0.03); and waist circumference of -1.42 cm (95% CI=-2.54, -0.29, p=0.01) were observed in favor of the intervention group.

CONCLUSIONS: Although the observed decrease in sitting time was not significant, a community-based, individually tailored, theory-based intervention program aimed at reducing sitting time may be effective for increasing standing and improving cardiometabolic health in sedentary adults.

TRIAL REGISTRATION: This study is registered at Clinicaltrials.gov (NCT00289237).