Effect of Reducing Sedentary Behavior on Blood Pressure

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.