(VP095) SEDENTARY MOST OF THE TIME: CAN SEDENTARY BEHAVIOR CANCEL THE BENEFITS OF FOCUSED DAILY EXERCISE ON ATHEROSCLEROSIS?

Background: As the prevalence of cardiovascular disease remains high, improved strategies are necessary to prevent onset. Although atherosclerosis has been associated with several risk factors, it is commonly identified in young and otherwise healthy populations, reinforcing the importance of developing new universal prevention strategies that may also be applied to individuals without known risk factors. The aim of this study was to determine the interaction of sedentary behavior and physical activity (PA) on cardiovascular health. We aimed to determine the independent and combined impacts of sedentary behavior and physical activity/inactivity on atherosclerosis burden and the cardiometabolic profile.

METHODS AND RESULTS: 125 participants aged 18 to 55 years (37.6 ± 11.2) were selected from an ongoing randomized control trial. All participants were healthy, without overt cardiovascular disease, risk factors or medication. Participants were assigned to one of four groups according to their level of PA (±500 MET-min/week) and sitting time (±7h/day). PA, sitting time, anthropometric measurements, blood pressure, fasting lipid profile, glycated hemoglobin were assessed at baseline, 1-year and 2-year follow-up. Carotid atherosclerosis burden and abdominal, hepatic, and cardiac adipose tissue volume were measured by magnetic resonance imaging. At baseline, active participants (≥500 METS-min/week) had lower resting heart rate (p=0.0186), fat percentage (p=0.0161), subcutaneous adipose tissue (SAT) (p=0.0078) as well as greater vessel wall volume (p=0.0281) and normalized lumen index (p=0.0118) of the common carotid arteries (NLIC) (NLI = lumen area/vessel area). Sitting time showed no independent or combined association with PA on either cardiometabolic profile or atherosclerosis burden. At 1 and 2-year follow-up, active participants developed less increase of systolic blood pressure (p=0.031), LDL-C (p=0.016), vessel wall volume (VVWB) (p=0.017), normalized lumen index of the carotid arteries (NLI) (p=0.022) and NLIC (p=0.005). Sedentary participants (≥7h/day of sitting time) had greater increase in waist circumference (p=0.035) and decrease of NLI (p=0.005). Associations were also observed between total PA and lower increase of SAT (p=0.0012), as well as between sitting time and lower increases of NLI (p=0.0026), NLIC (p=0.0331) and VVWB (p=0.0256). There was also a combined effect of PA and sitting time on VVWB (p=0.005), NLI (p=0.01) and NLIC (p=0.016) with active/non-sedentary participants showing the greatest increases while inactive/sedentary participants had the least.

Conclusion: Both physical activity and sitting time have distinct impacts on the cardiometabolic profile and atherosclerosis burden. We surmise that PA and sitting time have both an independent and a combined impact on endothelial function as evidenced by increased NLI.