Accumulation of Light-intensity Activity or Standing During a Workday Reduces Ambulatory Blood Pressure in Prehypertension

Abstract

INTRODUCTION: Accumulation of slow walking (1 mph) on a treadmill desk throughout a workday can lower ambulatory blood pressure (ABP) during and after work hours. The contribution of posture to this effect is unknown. PURPOSE: To compare ABP response to a worksite walking (WALK), standing (STAND), Cycling (CYCLE) and sedentary (SED) day in adults. METHODS: Nine overweight (BMI = 29±3 kg/m2) prehypertensive (130±15/76±11 mmHg) adults (30±15 yr) participated in this randomized repeated-measures study. Four conditions (WALK, STAND, CYCLE, SED) were randomly performed one week apart. WALK, STAND, and CYCLE conditions consisted of periodically increasing activity time to 2.5 hours over the course of an 8-hour work day. WALK (1.0 mph) and STAND (0.0 mph) were completed on a treadmill placed underneath a TREKDESK. During the CYCLE condition subjects pedaled on a Monark cycle ergometer at a cadence and energy expenditure equivalent to WALK. Subjects remained seated during the SED condition. Participants wore an ABP cuff (Oscar 2, SunTech Medical) from 8 am until 10 pm on all conditions. Linear Mixed Models were used to detect condition differences in systolic (SBP) and diastolic (DBP) blood pressure. Chi square was used to detect frequency difference of BP thresholds. RESULTS: There was a whole-day (during and after work hours) SBP and DBP treatment effect (P<0.001). SBP during STAND (132±4 mmHg), WALK (133±5 mmHg) and CYCLE (129±4 mmHg) were lower when compared to SED (137±4 mmHg) (P<0.001). CYCLE was lower than WALK (P=0.003). For DBP, nly CYCLE (70±4 mmHg) was lower than SED (73±4 mmHg; P=0.008). Compared to SED, WALK, STAND and CYCLE reduced SBP load (% of readings >140 mmHg) by 5%, 4%, and 14%, respectively (P<0.005). CONCLUSION: Compared to sitting, accumulating 2.5 h of light physical activity or standing during an 8-h workday may help reduce ABP during and after work hours.