Chronic And Acute Benefits Of Reduced Sitting In Individuals With Increased Cardiovascular Risk

Sedentary behavior increases the risk for cardiovascular and cerebrovascular disease. However, little work examined the causal link between a decline in sedentary behavior and cardio- and cerebrovascular function, and the potential underlying mechanisms for this relation. PURPOSE: to examine the chronic (16-week) and acute (3-hour) impact of reducing sedentary behavior on vascular and cerebrovascular function in subjects with increased cardiovascular risk. METHODS: This prospective study included 24 individuals with increased cardiovascular risk (65±5 years, 29.8±3.9 kg/m2). Before and after 16-week reduced sitting, using a mobile-Health device with vibrotactile feedback, we examined: i. vascular function (flow-mediated dilation (FMD)), ii. cerebral blood flow (CBFv, transcranial Doppler), and iii. cerebrovascular function (cerebral autoregulation (CA) and cerebral vasomotor reactivity (CVMR)). To better understand potential underlying mechanisms, before and after intervention, we evaluated the effects of 3-hour sitting with and without light-intensity physical activity breaks (every 30-minutes). RESULTS: The first wave of participants showed no change in sedentary time (n=9, 10.3±0.5 to 10.2±0.5 hours/day, P=0.87). Upon intervention optimization, the subsequent participants (n=15) decreased sedentary time (10.2±0.4 to 9.2±0.3 hours/day, P<0.01). This resulted in significant increases in FMD (3.1±0.3 to 3.8±0.4%, P=0.02) and CBFv (48.4±2.6 to 51.4.±2.6 cm/s, P=0.02), without altering CA or CVMR. Before and after the 16-week intervention, 3-hour exposure to uninterrupted sitting decreased FMD and CBFv, whereas physical activity breaks prevented a decrease (both P<0.05). CA and CVMR did not change (P>0.20). CONCLUSION: Long-term reduction in sedentary behavior in older subjects with increased cardiovascular risk improves peripheral vascular function and cerebral blood flow, and acutely prevents impaired vascular function and decreased cerebral blood flow. These results highlight the potential benefits of reducing sedentary behavior to acutely and chronically improve cardio-/cerebrovascular risk. Study is registered at the Netherlands Trial Register (NTR6387) (https://www.trialregister.nl/trial/6215).