Regular aerobic exercise improves blood flow to the brain, which should help keep older people more alert as they age, a new trial has revealed.
At least half an hour of brisk walking or jogging four to five times a week promoted better blood flow in and out of the brain among a small group of older adults, said study co-author Rong Zhang. He directs the cerebrovascular laboratory at the Institute for Exercise and Environmental Medicine, a collaboration between UT Southwestern and Texas Health Presbyterian Hospital Dallas.
“The intensity was like you’re rushing to a meeting where you’re 10 minutes late,” Zhang said. “You are walking briskly and you feel short of breath.”
The brain requires about 20% of the body’s total blood flow to maintain its function as an organ, he said.
But as people age, blood begins to flow less freely in and out of the brain, a condition called cerebrovascular impedance.
Less blood flow means the brain is receiving lower levels of oxygen and nutrients, Zhang said.
It also means that toxins could build up in the brain, as reduced blood flow is less able to remove waste products generated by the brain’s high metabolism.
To see if regular exercise could help people maintain healthy blood flow in the brain, Zhang and his colleagues recruited 72 people between the ages of 60 and 80 to participate in a year-long experiment.
Half were randomly assigned to an aerobic exercise group, while the rest were placed in a control group that did stretching and toning activities.
The aerobics group started with three half-hour exercise sessions a week and gradually increased to four or five sessions that could last up to 40 minutes.
After a year of exercise, the researchers performed brain scans and arterial tests to see how well blood was flowing in and out of the participants’ brains.
The aerobics group showed a significant improvement in cerebral blood flow at the end of the year, but the stretching and toning group did not.
This type of improvement in blood flow should lead to better brain health, said Dr. Donn Dexter, a neurologist at the Mayo Clinic in Eau Claire, Wisc., and a member of the American Academy of Neurology.
“The data on cognition-enhancing exercise is pretty strong,” Dexter said. “I hadn’t seen this tactic before. It’s interesting that they are looking at exercise as a way to improve vascular health within the brain. This adds further fuel to the hypothesis that exercise improves brain health.”
Current guidelines recommend that adults get at least 150 minutes a week of moderate-intensity exercise, Dexter and Zhang said.
“It’s hard to remember 150 minutes a week. Keeping track of that can be hard,” Dexter said. “So what I tell them is to do 30 minutes a day, because 30 minutes a day will give you that 150 minutes a week, even if you miss a day or two.”
This study shows that people can benefit from exercise at any age, as long as the participants were at least 60 years old, Zhang said.
“Exercise should be a lifelong habit. It’s never too late,” he said. “Research suggests that what’s good for your heart is good for your brain. That’s a message we need people to understand.”
At the same time, people shouldn’t feel they have to exaggerate, Zhang added.
“I haven’t seen any evidence to suggest that if you go to the extreme, like people who train for a marathon, you will receive more benefits compared to the program that we have recommended,” he said.
The clinical trial report was recently published in the Journal of Applied Physiology.
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