Starting an otherwise sedentary day with 30 minutes of some kind of moderate-intensity exercise — such as a brisk walk — may help older adults think more clearly and make better decisions throughout the day, according to an Australian study published recently in the British Journal of Sports Medicine.
The study also found that adding brief three-minute walking breaks during the rest of the day appears to provide an extra cognitive “boost.”
“This study highlights how relatively simple changes to your daily routine could have a significant benefit to your cognitive health,” said Michael Wheeler, the study’s lead author and a doctoral student in physical activity and behavioral epidemiology at the University of Western Australia, in a released statement.
This isn’t the first study to find that taking even small exercise breaks during a day of prolonged sitting can be good for our health. Wheeler and his colleagues at the University of Western Australia also recently reported, for example, that 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 women who are overweight or obese. And earlier this year, a team of American researchers found that swapping as little as half an hour of sitting time each day with physical activity helps reduce the risk of early death among middle-aged and older adults.
But not everyone is convinced that brief bouts of exercise are sufficient to counter the negative health consequences of prolonged sitting. A study published in April in the Journal of the American College of Cardiology reported that the negative health risk from prolonged sitting is eliminated entirely only among people who are highly active — those who engage in at least five hours of moderate to vigorous exercise per week.
What is certain is that Americans are now spending a record number of hours sitting — an average of 6.4 hours a day for adults, which is an hour more than a decade ago.
How the study was done
For the current study, Wheeler and his colleagues recruited 65 Australian men and women, aged 55 to 80. All were overweight or obese and had normal cognitive function (no memory or other thinking-related problems).
Each participant was brought into the lab on three different days, which were separated by at least six days. They were told to fast the night before, and were given the same standardized lunch and breakfast during each visit. Their activities during the visits varied, however, for when they arrived at the lab they were randomly assigned to one of these three conditions:
- Uninterrupted sitting for eight hours, except for bathroom breaks. (During these sitting sessions, the participants could read or work quietly on a laptop, but they had to avoid activities that might significantly raise their mental arousal, such as watching television.)
- 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
At the start and the end of each session, the participants underwent tests to assess various cognitive skills, including short-term memory, attention, visual learning and executive function (an umbrella term for several mental processes that enable us to organize and control our actions to achieve goals).
Blood tests were also taken before and after the sessions to measure the participants’ levels of brain-derived neurotropic factor (BDNF), a protein that plays an important role in the survival and growth of neurons in the brain. It also helps those cells transmit information.
What the study found
The study found that breaking up a sedentary day with a 30-minute morning walk and additional short walking breaks had no effect on the participants’ attention and visual learning skills. They did tend to perform executive function tasks better, however, on the day they got on the treadmill. And when the additional walking breaks were added to the day, the participants’ short-term memory skills also improved.
But interestingly — and rather puzzlingly — the addition of the short breaks caused the participants’ executive function abilities to dip a bit.
“These findings suggest that different patterns of physical activity may improve distinct aspects of cognition,” the researchers say.
The study also found that the amount of BDNF in the participants’ blood was higher during both days of exercise. Whether that finding means anything clinically — in other words, whether those exercise-induced higher levels have a direct effect on people’s thinking skills — is unclear. Indeed, Wheeler and his colleagues note that in this study, changes in BDNF levels were not significantly linked with cognitive outcomes.
Limitations and implications
The study comes with other caveats. Most notably, it involved a relatively small number of participants who lived in two communities in Australia. The findings may not be applicable, therefore, to broader, more diverse populations.
Still, plenty of previous research has shown that exercise — perhaps even in short bursts — has benefits for the brain as well as the body. And the exercise doesn’t have to involve walking. University of Maryland researchers reported last month that 30 minutes of cycling on a stationery bike improves semantic memory (the ability to recall words, concepts and numbers).
So get up and move about as much as you can — and in whatever way you can. As Wheeler and his colleagues conclude: “Uninterrupted sitting should be avoided, and moderate-intensity exercise should be encouraged for the daily maintenance of brain health.”
FMI: You’ll find an abstract of the Australian study at the website of the British Journal of Sports Medicine, but the full study is behind a paywall.