Abstract Body: Introduction: Sedentary behavior is associated with cardiovascular disease and diabetes, yet evidence from randomized controlled trials (RCT) demonstrating a causal effect of sedentary behavior on cardiometabolic biomarkers is scarce.

Hypothesis: A 3-month sedentary behavior reduction intervention will improve cardiometabolic biomarkers compared to controls.

Methods: The Reducing Sedentary Behavior on Blood Pressure (RESET BP) RCT tested the effect of a multi-component sedentary behavior reduction intervention on blood pressure (primary outcome) and other cardiometabolic risk factors after 3 months among 271 desk workers with high blood pressure. Primary findings revealed no evidence of a blood pressure reduction despite a 1.2 hours/day greater reduction in sedentary behavior. Here we considered secondary/exploratory outcomes including aldosterone, plasma renin activity (PRA), lipids, insulin and glucose, and HOMA-IR. Blood samples were obtained at baseline and 3-month follow-up, after an overnight fast and a 30-minute seated rest, stored at -80°F until the end of the study, and analyzed by a central laboratory using standardized assays. We performed analysis of covariance with adjustment for baseline values for comparing groups.

Results: RESET BP participants had mean age 45 years, mean blood pressure 129/83 mmHg, were 60% female, and 83% White. Among those with cardiometabolic biomarkers (n=173-188), intervention participants had a 14.97 ng/mL greater reduction in aldosterone (p=0.037) and 0.23 ng/mL/hour in PRA (p=0.046) over follow-up compared to controls, indicating a favorable change. Changes in other biomarkers showed no evidence of an intervention vs. control difference: LDL cholesterol (-2.35 mg/dL; p=0.443); HDL cholesterol (-0.72 mg/dL; p=0.543); triglycerides (3.52 mg/dL, p=0.627); glucose (-1.98 mg/dL; p=0.225); insulin (0.44 IU; p=0.723); and HOMA-IR (-0.10; p=0.808)

Conclusions: Despite no evidence of improvement in resting blood pressure or other biomarkers, intervention-related decreases in aldosterone and PRA may suggest a novel mechanism of benefit to the renin-angiotensin-aldosterone system with sedentary behavior reduction.