Short bursts of high-intensity exercise several times a week can improve memory in older adults, according to a new Canadian study.
And it wasn’t just a minor improvement. The study found that after only three months of such workouts, older adults tended to score about a third higher on a memory test.
The study’s authors believe their findings may point to a way of reducing some of the decline in memory that is associated with aging — specifically, a loss of high-interference memory. This form of memory helps people retrieve information from similar situations, such as remembering whether they took their last dose of medication today or yesterday.
“There is an urgent need for interventions that reduce dementia risk in healthy older adults,” says Jennifer Heisz, the study’s senior author and a professor of kinesiology at McMaster University, in a released statement. “Only recently have we begun to appreciate the role that lifestyle plays, and the greatest modifying risk factor of all is physical activity.”
The study was published last week in the journal Applied Physiology, Nutrition and Metabolism.
As background information in the study points out, high-intensity exercise has already been shown to improve memory in younger adults, although scientists aren’t sure how long or how hard people have to work to reap that benefit.
Nor is it certain that high-intensity exercise produces similar memory improvements in older adults.
To try to resolve those questions, Heisz and her colleagues recruited 64 older Canadian adults, aged 60 to 88. All were sedentary before the study began, but otherwise healthy. (The study defines sedentary as not engaging in more than an hour of low- or moderate-intensity physical activity per week.)
For the 12-weeks-long study, the researchers divided the participants into three groups. One group did a high-intensity workout three times a week for just under an hour each time. The workout consisted of walking on a treadmill at a moderate pace, but with four 4-minute “bursts” of high-intensity walking (intense enough to bring each participant’s heart rate up to 90 to 95 percent of the maximum heart rate for their age).
A second group also did the treadmill walk, but without the high-intensity bursts. The rest of the participants — the control group — attended a class that had them doing gentle stretching exercises.
The participants were instructed to not engage in any other physical activity during the duration of the study.
At the beginning and at the end of the study, the participants were given a series of cognitive tests, including ones that assessed high-interference memory. For the group that engaged in the high-intensity workouts, the change in scores on that memory test was dramatic — an average improvement of 30 percent.
The study also found a direct correlation between improvements in cardiovascular fitness and improvements in memory. In other words, the stronger the participants’ hearts became as a result of their workouts, the higher they tended to score on the memory test.
The other two groups saw no improvement in their memory scores. In fact, the stretching-only group experienced declines in both fitness and memory — a finding that suggests, write Heisz and her colleagues, “that some exercise, even if not enough to enhance memory, may help mitigate age-related decline in fitness to prevent memory loss.”
Interestingly, at the end of the study both of the treadmill groups demonstrated higher averages scores in a cognitive skill known as executive function — the ability to be focused, get organized and make decisions.
‘It’s never too late’
This is a single small study involving people living in one metropolitan area in a single country. Its findings may not be applicable to other, more diverse populations.
Another limitation of this research is that the participants self-reported how much exercise they got before they entered the study. If those reports were inaccurate (and self-reports can be), the study’s results may also be inexact.
Still, the findings are intriguing. They also support a Japanese study published earlier this year that found that interval walking (short bursts of high-intensity walking within a longer, slower walk) improved fitness and health in older adults.
“It’s never too late to get the brain health benefits of being physically active, but if you are starting late and want to see results fast, our research suggests you may need to increase the intensity of your exercise,” says Heisz.
Of course, older adults should not start a high-intensity exercise program without first consulting their doctor. Any such program will need to be tailored to each person’s fitness level.
FMI: You’ll find an abstract of the study on the website for Applied Physiology, Nutrition and Metabolism, but the full paper is behind a paywall.