Skipping exercise in favor of less demanding activities, such as sitting or lying down, was linked to a mild decline in memory and thinking skills, according to a study published Monday in the journal. Journal of Epidemiology and Community Health.

The differences, though small, show how even minor changes in physical activity levels can affect a person’s health, including brain health, said study lead author John Mitchell, a researcher at the Institute of Sport, Exercise and UK Health.

Mitchell and his colleagues used data from the 1970 British cohort study — an ongoing study tracking the health of a group of people born in the UK in 1970. The study findings were based on data from nearly 4,500 people followed between 2016 and 2018.

Participants provided information about their health, background, and lifestyle. They were also asked to wear an activity tracker for at least 10 consecutive hours a day for up to seven days, including when sleeping and bathing.

During the study, the participants underwent a series of tests that assessed their ability to process and remember information.

Participants, on average, each day did 51 minutes of moderate to vigorous exercise; about six hours of light activity, such as a slow walk; and about nine hours of sedentary behavior, such as sitting or lying down. They also slept, on average, around eight hours.

Moderate to vigorous activity in the study was considered anything that would get «the heart pumping» or make someone «feel hotter,» Mitchell noted.

After analyzing the participants’ activity data, the researchers found that those who skipped exercise in favor of eight minutes of sedentary behavior saw a 1% to 2% decrease in their cognitive scores.

The researchers observed similar declines in cognitive performance when people replaced vigorous exercise with six minutes of light physical activity or seven minutes of sleep.

But the opposite was also found to be true: exercising instead of sitting improved cognitive performance. Replacing sitting or lying down with nine minutes of vigorous exercise was linked to a more than 1% increase in cognitive scores, the study found.

The findings should encourage people to move more, said Aviroop Biswas, assistant professor of epidemiology and associate scientist at the Institute for Work and Health in Toronto.

«Physical activity is associated with a whole host of benefits, so you really want to promote as much regular physical activity as possible,» said Biswas, who was not involved in the research.

He Department of Health and Human Services recommends that adults get at least 150 minutes of moderate to vigorous physical activity each week, plus two days of muscle-strengthening training.

The link between more exercise and better brain performance isn’t yet clear, but it’s likely a result of how the body’s cardiovascular system works, Biswas said.

«When you’re active, you’re essentially improving the strength of your heart and you’re improving your heart’s ability to pump blood throughout your body and to one of the most important organs: your brain,» he said.

Conversely, when people don’t get enough exercise, it can lead to a host of health problems, including those that affect the brain, such as dementia, said Marc Roig, a professor of physical and occupational therapy at McGill University in Montreal, who He was also not involved in the new study.

Exercise intensity is also important, Roig added, noting that people in the study who engaged in light physical activity instead of more vigorous activity also experienced decreased cognitive performance.

Scientists are still trying to determine which exercises are best for improving people’s overall health and preventing chronic disease, he said.

Mitchell, the study author, noted that light activity is still preferable to sitting.

«It seems unquestionable that light activity is better than sitting for many facets of health, but the jury is still out on what the critical intensity ‘threshold’ is for optimal health, including cognitive health,» he said.

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