A half hour of moderate to vigorous exercise at the start of the day may help lower blood pressure for the remainder of the day among people who are overweight or obese, according to a study published in the journal Hypertension.
The study also found that taking frequent breaks from sitting throughout the day enhances the beneficial effect of exercise on blood pressure. But that effect was seen only among women.
“For both men and women, the magnitude of reduction in average systolic blood pressure following exercise and breaks in sitting, approached what might be expected from antihypertensive medication in this population to reduce the risk of death from heart disease and stroke,” said Michael Wheeler, the study’s lead author, in a released statement.
“This reduction was greater for women,” he added. Wheeler is a doctoral student in physical activity and behavioral epidemiology at the University of Western Australia.
The study adds to a substantial body of evidence that has shown exercise can help keep blood pressure at healthy levels. More recently, studies have begun to report that interrupting sitting with short exercise “breaks” can also help reduce blood pressure.
“Traditionally, the health effects of exercise and sedentary behavior have been studied separately,” said Wheeler. “We conducted this study because we wanted to know whether there is a combined effect of these behaviors on blood pressure.”
How the study was done
For the study, Wheeler and his colleagues recruited 67 volunteers (35 women, 33 men) between the ages of 55 and 80. All were overweight or obese, and 37 percent had high blood pressure (defined as 130/80 mmHg or above).
The participants were brought to the University of Western Australia on three different days, which were separated by at least six days. On each visit they were randomly assigned to one of these three conditions:
Uninterrupted sitting for eight hours (getting up only for bathroom breaks)
Sitting for one hour, followed by 30 minutes of exercise (walking on a treadmill at moderate intensity), and then sitting again (uninterrupted) for 6.5 hours
Sitting for one hour, followed by 30 minutes of exercise, and then sitting for 6.5 hours — but this time getting up for a three-minute, light-intensity walking break every 30 minutes
The participants ate identical meals on the night preceding each visit and during the experiment itself. Their blood pressure and levels of adrenaline (a stress-related hormone that increases blood pressure) were measured repeatedly throughout the day.
The study found that blood pressure — particularly systolic blood pressure — was lower, on average, among the participants on the day they engaged in a 30-minute morning exercise than on the other two days.
That finding was expected. But the study also discovered that women (but not men) experienced a further statistically significant reduction in blood pressure on the day they exercised and took frequent breaks from sitting.
Systolic blood pressure is the first of the two numbers in a blood pressure reading. It measures the pressure in your blood vessels when your heart beats. The second number, diastolic blood pressure, measures the pressure in your blood vessels when your heart is resting between beats.
Both numbers in a blood pressure reading are important for determining heart health, but having a raised systolic blood pressure carries a greater risk of heart attack, stroke and other cardiovascular events.
Here are the specific findings from the study:
The average systolic blood pressure of the participants was 120 mmHg when they sat uninterrupted for the entire day.
That average dropped by 3.4 mmHg on the day when they exercised for 30 minutes in the morning.
It dropped an additional 1.7 mmHg (for an average total reduction of 5.1 mmHg) on the day that included the half hour walk and the shorter exercise breaks. But that extra drop in blood pressure occurred mostly among the women participants. Their blood pressure fell 3.2 mmHg, on average, when they exercised for half an hour and interrupted their sitting with short walks.
The reason for that gender difference is unclear.
“We cannot say for sure that breaks in sitting alone had no blood pressure lowering effect in men, as any effect could have been masked by the preceding effect of exercise,” said Wheeler.
Limitations and implications
The study comes with several important caveats. Most notably, it had a relatively small number of participants, and it measured their blood-pressure-related responses to exercise on only three days.
We don’t know, therefore, if the changes in blood pressure observed on these days would translate into longer-term health benefits.
Nor can this study tell us if a daily half-hour walk coupled with frequent breaks from sitting is as effective as taking medications for lowering blood pressure. The study did not directly compared exercise with drugs used to treat high blood pressure.
Any change in medications should, of course, always be discussed with your doctor.
Yet, taking a daily walk — and avoiding long stretches of uninterrupted sitting — is a great idea for almost everyone. And the benefits go far beyond lowering blood pressure and the risk of heart disease. Walking for just 30 minutes a day is also associated, for example, with a lower risk of type 2 diabetes, depression and certain cancers.
It’s also been linked to a longer life.
FMI: You’ll find an abstract of the study on the website for Hypertension, but the full study is behind a paywall. Hypertension is a publication of the American Heart Association.