ORLANDO – Interrupting prolonged sitting with brief bouts of light-intensity activity throughout the workday resulted in an impressive drop in blood pressure in overweight sedentary men and women with type 2 diabetes, Bronwyn Kingwell, Ph.D., said in a video interview at the American Heart Association scientific sessions.
A total of 24 such individuals were randomized in crossover fashion to a 3-day study conducted under controlled conditions in a physiology lab. On one day participants did what they usually do: They sat at their desks for an 8-hour workday. On another day they rose from their desks every 30 minutes for 3 minutes of walking down the hall at a 2-mph pace. And on yet another day they stood up every 30 minutes and did 3 minutes of simple resistance activities at their desks: half squats, knee raises, calf stretches.
Blood pressure was measured eight times per day, and plasma norepinephrine as a measure of sympathetic activity was measured nine times. At the end of the light walking day, subjects’ blood pressure was on average 14/8 mm Hg lower than on the uninterrupted sitting day. On the simple resistance activity day, it was 16/10 mm Hg lower.
“This is quite an impressive reduction, and more than we might have anticipated. It’s similar to the type of reduction you might see with single-drug antihypertensive therapy. And I thought it was interesting that two-thirds of subjects were already taking antihypertensive drugs,” observed Dr. Kingwell, head of metabolic and vascular physiology at the Baker IDI Heart and Diabetes Institute in Melbourne.
“I think the new thing here is that even with these very small bouts of activity – just 3 minutes – we’re getting this reduction that’s sustained throughout the day, provided you break it up every 30 minutes,” she said. “We’ve seen an increase in sitting behavior in most industrialized countries, particularly over the last 10 years, and we also see low adherence to structured exercise programs. The approach examined in this simple study may represent a practical strategy which could contribute to blood pressure reduction in a group that is at high risk.”