effect of reducing sedentary behavior on blood pressure

Conditions: Hypertension; Prehypertension

Summary: this is a 2-arm, 3-month randomized trial comparing a novel sedentary behavior intervention vs. control in working adults (n=271). the primary outcome is resting systolic blood pressure (sbp) at 3 months; secondary outcomes will be resting diastolic blood pressure (dbp), ambulatory blood pressure (abp), and carotid-femoral pulse wave velocity (cfpwv). also, best practice objective activity monitoring will be leveraged in the analysis of abp to account for recent activity and posture and will inform adherence and dose-response relationships.we will also measure plasma renin activity and aldosterone as a potential mechanism of blood pressure reduction, and insulin and glucose as exploratory outcomes.

hypertension (htn) is the most common major risk factor for cardiovascular disease (cvd), affecting 1 in 3 american adults. also, nearly another 1 in 3 adults has prehypertension (prehtn). moderate-to-vigorous intensity physical activity (mvpa) is known to decrease bp. guidelines recommend 150 min/week of mvpa performed in continuous bouts of ≥10 min (i.e., bouted mvpa). sedentary behavior (sed), defined as sitting or reclining with low energy expenditure, has gained attention as a highly prevalent and distinct behavior from mvpa that is independently associated with higher bp, arterial stiffness, cvd, and mortality. these data, coupled with the fact that americans spend more than half of the waking day in sed, suggest sed as a novel intervention target. yet, despite heightened public perception of sed as a health risk, there is a dearth of randomized clinical trials demonstrating that sed reduction will lead to health benefits, including reduced bp. decreasing sed more substantially could improve bp, but this remains unclear in the absence of larger randomized trials with effective sed interventions. thus, to test initial efficacy, the effect of reducing sedentary behavior on blood pressure (reset-bp) has the following specific aims: specific aim 1: to evaluate the efficacy of our intervention targeting decreased sedentary behavior (sed) over 3 months. outcomes include sbp (primary), dbp, abp (nocturnal, daytime seated, daytime non-seated), and cfpwv. we hypothesize that the 3-month sed intervention will decrease sbp, dbp, abp and cfpwv vs. controls specific aim 2: to explore whether renin-angiotensin-aldosterone (raas) activation (increased plasma renin activity (pra) and aldosterone) mediates changes in bp elicited by sed reduction specific aim 3: to examine associations between achieved reductions in sed, increases in replacement behaviors (i.e., standing, other light-intensity physical activity (lpa), and bp reduction these aims will be evaluated with a 2-arm, 3-month randomized trial comparing a novel sed intervention vs. control in 271 adults. the study will recruit adults with untreated, elevated blood pressure (sbp 120-159 mmhg or dbp 80-99 mmhg) and desk jobs that require prolonged sed to maximize the opportunity for sed reduction. the intervention will target currently recommended levels of sed reduction for desk-based employees (2-4 hours/day with frequent postural changes) and will use a behavioral intervention including individual in-person (1/month) and phone counselling (1/month) focused on goal setting, overcoming barriers, self-monitoring, social support, and stimulus control. in addition, the intervention will include environmental modification via provision of a sit-stand desk attachment and external prompting via text messaging and a wrist-worn inactivity prompter.

Eligibility criteria:
inclusion criteria: 1. age 21-65 years 2. sbp 120-159 mmhg or dbp of 80-99 3. inactive (engages in less than 150 min/wk of moderate + 2 x vigorous intensity physical activity) 4. currently perform deskwork for ≥ 20 hr/week at a desk compatible with the sit-stand attachment 5. employment within an approximate 25-mile radius of the university of pittsburgh 6. stable employment (≥ 3 months in current job, plan to be in current job for the next 3 months) 7. supervisor approval to join the intervention 8. possession of a cellular phone able to receive text messages exclusion criteria: 1. sbp ≥ 160 mmhg, dbp ≥ 100 mmhg 2. use of antihypertensive or glucose controlling medication 3. comorbid condition that would limit ability to reduce sedentary behavior (e.g. musculoskeletal condition, current chemotherapy) 4. history of ischemic heart disease, chronic heart failure, stroke, or chronic kidney disease 5. unable to obtain consent from primary care provider or physician to participate 6. current use of sit-stand/standing desk, sedentary behavior prompting device, enrollment in a weight loss or exercise study or program, recent (\< 1 year) or planned bariatric surgery 7. currently pregnant or pregnant in that last 6 months; breastfeeding currently or in the last 3 months 8. plans to be away from your desk for an extended period (\>1 week) during the study period

Keywords: sedentary behavior light intensity physical activity behavioral intervention office workers blood pressure pulse wave velocity randomized clinical trial