The health benefits of regular cardiovascular fitness have been proven again and again by various studies. Now, a new study published in the journal Neurology suggests these benefits include better memory and thinking skills in middle age.

The study, led by David Jacobs Jr., PhD, from the University of Minnesota-Minneapolis, defined middle age as being between the ages of 43 and 55.

"This is one more important study that should remind young adults of the brain health benefits of cardio fitness activities such as running, swimming, biking or cardio fitness classes," Jacobs says.

Being fit in a cardiorespiratory sense means the body is able to efficiently transport oxygen to the muscles, which are then able to effectively absorb oxygen during physical activity.

Good thinking skills and memory in an aging population are of great importance to US public health bodies. According to the Centers for Disease Control and Prevention (CDC), the current growth in the number and ratio of older adults is "unprecedented in the history of the United States."

The organization cites two factors contributing to this growth: longer life spans and aging baby boomers. Additionally, by 2030, the CDC says that older adults will comprise around 20% of the US population.

For this current study, Jacobs and colleagues focused on factors from young adult life that could impact brain health in middle age. A total of 2,747 healthy young adults under the age of 25 completed treadmill tests in the first year of the study and then once again 20 years later.

The researchers also used cognitive tests taken 25 years from the start of the study to measure verbal memory, psychomotor speed - which is the relationship between physical movement and thinking skills - and executive function.

Every extra minute on the treadmill increased cognitive performance

During the treadmill tests, at the start and 20 years later, the study participants walked or ran while both speed and incline increased. They did this until they either could not continue or had shortness of breath. In this sense, the treadmill tests were similar to a cardiovascular stress test, the researchers say.

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Participating in cardio activities in young adulthood, like running, may maintain good thinking skills in middle age, the research shows.

On average, the participants lasted an average of 10 minutes on the treadmill during the first test in their youth. Then, 20 years later, that average decreased by 2.9 minutes.

The researchers found that for every extra minute on the treadmill during the first test, individuals recalled 0.12 more words correctly during the memory test and correctly replaced 0.92 more numbers with symbols in the psychomotor speed test 25 years later.

These results held true even after the team adjusted for factors such as diabetes, smoking and high cholesterol.

Additionally, individuals with smaller time decreases on the treadmill 20 years later were more likely to perform better on the executive function test, compared with those who had larger decreases. The researchers explain the participants were better at correctly stating ink color when the word "yellow," for example, was written in green ink.

Jacobs notes that though the changes observed in the study were "modest," they were significant, and the tests used on the participants have been proven to be "among the strongest predictors of developing dementia in the future."

How brain function works is 'still not well understood'

Speaking with Medical News Today, Jacobs said that it is not well understood how brain function - "thinking skills" - works. He explained that the brain requires a lot of oxygen, delivered by blood vessels, which is potentially why physical activities and behaviors that are good for the blood vessels are, in turn, good for the brain.

Jacobs continued:

"There are probably many other ways in which fitness and maintaining an active life are beneficial. One is tuning up mitochondria, which are central in maintaining energy turnaround in the body.

From the perspective of individual and societal decision making, the mechanisms are less important, however; probably people who have poorer thinking skills in middle age have lesser jobs and less income, for example."

In trying to maintain cognitive health in the aging population of the US, the CDC established the Healthy Brain Initiative in the Healthy Aging Program in 2005, with help from Congress, and in 2007, a 5-year framework was created to guide a linked up public health response from many organizations.

Now, the CDC are creating a new Road Map that, among other initiatives, outlines how both state and local public health agencies can promote cognitive functioning.

Jacobs told us that he and his colleagues hope to carry out their life course study in the current participants, "which will give a glimpse of how youth affects old age." However, he says this depends on the funding for the National Institutes of Health (NIH).

Medical News Today recently reported on a study published in the American Heart Association's journal Circulation, which suggested elevated heart risks in young adulthood are linked with lower cognitive function in mid-life.