Exercising for 30 minutes improves memory, study suggests

For cycle-to-work commuters and those who start the day with a brisk walk, the benefits of banking some early exercise is well understood.

Now scientists believe activity is not just a good idea for improving the day ahead – physical activity could be associated with small increase in memory scores the next, too.

A study from University College London has shown that 30 minutes of moderate to vigorous activity and sleeping for at least six hours at night, could contribute to improved cognitive performance the following day.

“The takeaway is just [that] physical activity is good for your brain and good sleep helps that,” said Dr Mikaela Bloomberg, first author of the study.

The researchers noted physical activity had previously been associated with both short-term improvements in cognitive function and a reduced risk of dementia.

However, Bloomberg noted many studies looking at short-term impacts had been laboratory based, and primarily tracked responses on a timescale of minutes to hours. These studies suggested benefits could be down to an increased blood flow to the brain and stimulation of chemicals known as neurotransmitters.

Now researchers say they have looked at the short-term impact of physical activity carried out in real life, not only finding benefits to the brain but revealing these appear to last longer than expected.

Writing in the International Journal of Behavioral Nutrition and Physical Activity, Bloomberg and colleagues report how 76 adults aged 50-83 years old, and who did not have cognitive impairment or dementia, were asked to wear an accelerometer for eight days to track their sleep and physical activity as they carried out their normal life.

Each day, participants were also given simple online cognitive tests to probe their attention, memory and processing speed, among other faculties.

The team said their results reveal that each 30-minute increase in moderate to vigorous physical activity on the previous day corresponded to a 2-5% increase in episodic and working memory scores the next, although only the latter remained once participants’ sleep data was considered.

While Bloomberg noted it is difficult to say whether this corresponds to a tangible – clinical – difference for participants, she said the next step is to carry out similar work in people with cognitive impairments.

“The idea is for people who have mild cognitive impairment, a very minor boost in cognitive performance on a day-to-day basis can make a huge difference,” she said.

The team also found each 30-minute increase in sedentary behaviour was associated with a small drop in working memory scores the next day – although Bloomberg said exactly how sedentary time is spent could be important – while those who slept at least six hours a night had higher scores for episodic memory, attention and physical response speed the next day, after taking into account levels of physical activity, than those who had less sleep.

However, the study has limitations, including that the participants had high levels of education, excellent health and high levels of everyday physical activity.

Bloomberg added it is not clear exactly what is driving the impact of exercise on memory the following day, with benefits from neurotransmitters only thought to last for a few hours. She also noted different mechanisms may be behind long-term benefits of exercise to the brain.

The study ties into a focus on protecting our brains as we age. “We all experience cognitive decline as we get older, it’s a normal part of ageing,” Bloomberg said. “So that’s the age group where we start to think: what are these little things we can do on a day-to-day basis to improve our cognitive function and our independence and social participation?”