iStock High blood pressure, aka hypertension, affects more than 5 million Australians — no surprise there’s an ongoing hunt for methods to prevent and treat the condition.
Such a method is suggested by a new study conducted by a team led by University of Western Australia and Baker Institute researchers.
Their research found that men and women who exercised in the morning lowered their blood pressure, and that women lowered theirs even further by taking brief but frequent breaks from sitting over the rest of the day.
It’s well-established exercise lowers blood pressure, while extended periods of sitting have been observed to increase it. Noting that, the researchers set out to test whether exercise’s powers can be enhanced by breaking up those sitting periods.
"This is a relevant question because in the real word, it is possible for a person to get their recommended daily amount of exercise but also to accumulate high volumes of sitting," said the study’s lead author, PhD candidate Michael Wheeler.
He and his team recruited 67 men and women aged 55 to 80, who were all overweight or obese, and ran them all through three experiments that each lasted eight hours.
In one experiment, participants sat without moving the whole time. In a second, they sat for an hour, walked on a treadmill for 30 minutes at a moderate intensity , then sat for the remaining six-and-a-half hours. In the third, they sat for an hour, did their 30 minutes of exercise, but then broke up their sitting with a three-minute light walk every half hour.
Their blood pressure, heart rates and adrenaline levels were measured throughout. The results are published in the American Heart Association journal Hypertension .
The 30-minute bout of exercise significantly lowered all participants’ blood pressure, particularly their systolic blood pressure: that’s the first number in a blood pressure reading, which reflects pressure when the heart is beating.
High systolic blood pressure is generally a better predictor of dire cardiovascular events than diastolic blood pressure — the second number in a blood pressure reading, which reflects pressure between heartbeats. (An example of a blood pressure reading is 120/80, which is considered normal.)
When they just exercised, participants lowered their systolic blood pressure by an average 3.4 points compared to when they just sat. But when they exercised and took breaks from sitting, they lowered it by an average 5.1 points — compare that to medications for high blood pressure, which can lower it by 8-9 points.
"As the majority of participants in our study did not have hypertension, we see this result as promising from the perspective of prevention," Wheeler said.
"However, it would be interesting to do a similar study in the future and include only participants with hypertension to see if the reductions in blood pressure would be larger."
Interestingly, that added reduction in blood pressure from the walking breaks was almost entirely accounted for by the women, with the men appearing to gain nothing.
It’s not clear why — it could be down to varying adrenaline responses to exercise, or that the women were postmenopausal, a time of life that increases the risk of cardiovascular disease.
But Wheeler pointed out that it’s impossible to say for sure that breaks in sitting alone had no blood pressure lowering effect in men.
"There could have been an effect that was masked by the preceding bout of exercise," he said. "Future studies will need to test for sex difference in the blood pressure response to breaks in sitting alone."
He added that there’s a wealth of research showing that breaking up periods of sitting has other health benefits, such as improved blood vessel function, and lowering glucose and insulin levels after a meal.
"It is because of this that we would still advise men to reduce and break up their sitting," he told Coach.
The study is compelling because it mirrors real-world behaviour — you might go for a jog in the morning, then make a point of taking breaks from your desk job the rest of the day, which could benefit your blood pressure. Wheeler said he hopes that future studies will examine the health effects of combining different behaviours in such a way.
"Because high blood pressure has also been associated with impaired cognitive function, we are also interested in the combined effects of exercise and sedentary behaviour on aspects of brain health," he said.
"We hope that future studies investigating the combined effects of these behaviours may inform the future design of exercise interventions seeking to improve markers of cardiovascular risk."
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