How a 5-minute walk after every half-hour of sitting helps lower blood pressure and blood sugar levels and could save you from an early death
- Sitting still for too long is an occupational hazard for many of us, putting us at greater risk for heart disease, diabetes, cancer and dementia
- A new study shows that short, frequent walks are an antidote to this – muscles regularly activated help regulate blood sugar levels and blood flow
Given I take a brisk 30-minute walk first thing every morning and again each evening, I didn’t see any risks in sitting on my backside for the bulk of the day.
I imagined I could sit smugly at my desk for up to 10 hours without moving much, except for the odd trip to the bathroom or a stretch and a yawn, or a dawdle around the garden with the dog in search of inspiration.
But that’s not the case, says Keith Diaz, a certified exercise physiologist and assistant professor of behavioural medicine at the Columbia University Irving Medical Centre in New York.
“Exercising daily does not alone reverse the harmful health effects of sitting,” he warns.
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As a result, they are also at much greater risk of early death.
Diaz, who has just published a study on the hazards of sitting too still for too long, says getting up to move throughout the day, no matter how that movement manifests, significantly affects blood sugar and blood pressure.
Muscles serve an important role in regulating blood sugar levels, but they need to be used and contracted to do this, Diaz says.
His study suggests that short, frequent walks throughout the day work to activate muscles regularly and that this in turn helps them serve as better blood sugar regulators.
It’s not just that moving is good for us, it’s that sitting still is bad.
“The sitting posture creates bends and constrictions in the blood vessels of the legs. This ultimately changes blood flow and can lead to increases in blood pressure,” he says.
Short, frequent walks can help prevent the changes in blood pressure by regularly restoring blood flow to the legs, he says.
Sitting too still for too long is an occupational hazard for many of us who are bound to desks and devices.
That’s especially true for those who work from home and don’t have the temptation to slink around an office saying hello to everybody.
Diaz’s research found that, on average, adults in the US are sedentary for over three-quarters of their waking day – that’s 11 to 12 hours a day. More than half of that sedentary time is accumulated in periods of uninterrupted sitting of at least 30 minutes.
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Technological advances in our lives are largely to blame.
Taking the US as an example, in 1950, the average number of hours a household spent watching television each day was about four. Today, it’s around eight.
In 1950, American adults spent an average of 15 minutes a day behind the wheel of a car. Today, it’s nearly an hour.
In 1950, 16 million US adults worked a sedentary job. Today, more than 60 million do.
These trends are doubtless duplicated across the developed world.
There is no need to feel overwhelmed at the thought of building more physical activity into your busy day, Diaz says. Think in terms of microdosing: five minutes every half-hour.
Get up from your chair, get moving for 300 seconds and you can sit back down again.
But why five minutes? And what prompted the study?
Public health guidelines are clear, Diaz says – we should “sit less, move more”. But they’re not clear enough: how much do we need to move in a day of sitting at a desk, and how often?
“Just as we have recommendations on how many fruits and vegetables we should eat each day and how much we should exercise, we set out to find an answer for how to combat the harms of sitting.”
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The aim of the study, Diaz says, “was to find the least amount of walking one could do to offset the harmful health effects of sitting”.
The team tested four different “doses” of walking and measured physiological changes – namely blood sugar and blood pressure, two important risk factors for heart disease.
Five minutes of light walking every half-hour was the highest “dose” and was the only one that reduced blood sugar levels substantially compared with sitting all day, Diaz says. Other doses tested included one minute of walking after every 30 minutes of sitting, one minute after 60 minutes, and five minutes every 60.
Those five minutes every half an hour also had a dramatic effect on blood sugar spikes after eating, cutting them by 60 per cent, and helped blood pressure fall by four to five points compared with sitting all day.
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Shorter, less frequent walks were better than none, but not as effective as the five-minute walks.
And the benefits of these mini-walks weren’t just physical.
Short walks break up the day so you feel more energised, he explains – and you’ll probably be able to focus better.
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Right. That’s 30 minutes. I’m off to the kitchen to make a cup of coffee and a piece of toast. Back in five.
