Exercise Overview

Exercise Page

Exercise Overview

Reviewed by

Prof Kirk Erickson
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Why the benefits of exercise are worth bottling

It’s often said that if the benefits of exercise could be bottled, we would have the magic ‘health’ pill the world has been waiting for.

And when it comes to brain health, the rewards are no less profound.

A wealth of scientific research has shown that greater amounts of physical activity – the umbrella term for any type of movement – are associated with a reduced risk of dementia in later life.

Not only that, but the good news is it’s never too late to start reaping the brain benefits of moving more, whatever your age.

There is even evidence that exercise can slow decline in patients with mild cognitive impairment (MCI) – a small but noticeable change in memory and thinking skills that can (but not in all cases) progress to Alzheimer’s disease.

One large review concluded that being particularly active reduced the risk of developing all types of dementia by 28% – and the risk of developing Alzheimer’s disease by 45%.

So what counts as being active?

Generally speaking, the scientific literature in this area divides physical activity into two areas – leading a more active lifestyle, such as taking the stairs rather than the lift, and so-called purposeful exercise, such as brisk walking, running, and so on.

For many people, the thought of doing strenuous exercise is daunting – or sometimes impossible due to restricted mobility.

And while there’s evidence that the more vigorous the level of your activity, the bigger the benefit to your brain health (more of which later), what’s really encouraging is that even just being more active in everyday life can make a significant difference to your brain health, and reduce the risk of diseases such as dementia later in life.

We will also look at the recommendations around the duration and types of exercise to reap the most benefit.

How being active slows down brain ageing

There are various ways in which moving more is thought to boost our brain health.

  • It changes your brain structure

    Research has repeatedly shown that physical activity can change the size and function of different areas of the brain – stopping them from shrinking – and so lowering the risk of cognitive decline and diseases such as Alzheimer’s later in life.

    There are certain parts of the brain that are associated with memory and learning – in particular, the hippocampus and pre-frontal cortex.

    And having more grey matter in these areas – i.e. these areas of the brain being bigger – is linked to a reduced risk of memory problems – and therefore Alzheimer’s disease.

    One landmark study found that people who walked around one mile a day still showed benefits nine years later. Specifically, the walkers had more grey matter in several brain areas including the pre-frontal cortex and the hippocampus.

    This, in turn, was associated with a two-fold reduced risk of developing cognitive impairment a further four years later.

    Another study found that people who were fitter had larger hippocampal areas even after scientists took their age, gender and level of education into account.

  • It may help reverse some age-related changes in the brain

    There is a compound found in the brain called N-acetylaspartate (NAA) – a molecule that is thought to reflect cell integrity – and lower levels of it later in life have been linked with Alzheimer’s. However, research has found that higher levels of fitness can offset the age-related reduction in NAA levels - and that higher NAA levels are associated with better working memory performance. 

  • It may lower the risk of Alzheimer's in those with a pregenetic disposition to it

    Not only that, but the benefits of physical activity appear to be greater in those with an elevated risk of Alzheimer’s disease. Interestingly, research has found this beneficial effect to be more pronounced in women, who have a genetic predisposition to Alzheimer’s disease

  • It helps to boost memory and efficiency of our brain's "wiring"

    Physical activity increases levels of a substance called brain-derived neurotropic factor (BDNF). Dubbed ‘Miracle-Gro’ for the brain, BDNF is a molecule that improves how well brain cells function, encourages new ones to grow and also protects them from stress and death.

    BDNF is involved in long-term memory formation and may also increase how effective the ‘wiring’ is in the hippocampus – a part of the brain strongly linked with memory. Higher levels of BDNF have also been linked with a larger hippocampal volume, while low levels are associated with ageing and Alzheimer’s disease.

  • It boosts blood flow to the brain

    As your heart rate increases during exercise, so too does blood flow to the brain. As a result, your brain is exposed to more oxygen and nutrients.

The good news? It's never too late to reap the brain benefits of being physically active

Scientific research has shown that the brain’s ability to modify its connections, or re-wire itself – a phenomenon known as neuroplasticity (you can read more about this in our Active Mind pillar) – continues well into late adulthood.

Essentially, this ability of the brain to repeatedly rewire itself means it’s never too late to gain the benefits of being more physically active – whatever your age.

In fact, evidence indicates that people who lead inactive or sedentary lifestyles stand to benefit more from an increase in physical activity than those who are already physically active and take up a new exercise regimen.

One interesting study compared the brain health benefits of regular walking compared with performing regular stretching and toning exercises among a group of older adults.

  • At the start of the trial, both groups had similarly sized hippocampal regions – the part of the brain implicated in memory impairment and Alzheimer’s disease
  • After one year, however, the stretching and toning group showed about a 1.5% decline in the size of the hippocampus, on average. The researchers said this rate of decline was consistent with the average annual rate of annual decline in healthy people aged over 50
  • People in the walking group, however, showed a 2% increase in the size of their hippocampus.

Therefore, this study suggested that starting a new exercise regimen later in life can have very real benefits for the brain.

Other research has found that the biggest brain health benefits are reaped when physical activity starts early in life – ideally as a teenager. However, women who were physically inactive as teenagers but who then became active in midlife had lower odds of developing cognitive impairment than those who remained sedentary into their later years.

Indeed, women appear to enjoy more brain-boosting benefits than men when they take up exercise later in life.

A study that compared the effectiveness of a 12-month moderate-intensity walking programme resulted in improved attention and memory in older women with mild cognitive impairment – whereas in men, only memory was improved.

Can exercise help people with memory problems?

It seems so. In one trial involving people suffering from cognitive impairment – problems with memory and thinking – 24 weeks of physical activity led to improvements in their brain functioning. Even better, these benefits remained for six months after the trial had finished, showing a long-term effect of the exercise intervention.

In another study involving patients with mild cognitive impairment, participation in both aerobic training (a more high-intensity form of physical activity) and a stretching and toning programme was associated with improved cognitive performance.

Meanwhile, a trial that compared aerobic training with resistance (i.e. strength) training in women with mild cognitive impairment, found that aerobic training ‘significantly increased hippocampal volume’.

So what type of physical activity has the most benefit?

At the moment, there is little concrete evidence about exactly how much physical activity is needed to gain long-term brain health benefits.

However, scientific literature suggests that effects can usually be seen between a period of six months and a year, but this may depend on the type and intensity of the physical activity being performed and also the population being studied.

In 2016, the Global Council on Brain Health, an independent panel of scientists, doctors, academics and policy experts which provides trusted information on how to maintain and improve brain health, produced a list of recommendations for physical activity and brain heath.

Overall, this report suggested a two-pronged approach: doing purposeful (organised) exercise and being active in our day-to-day lives.

 

Active lifestyle

Active Lifestyle - incorporating movement in day-to-day activities

  • Walking to work or the shops instead of driving
  • Taking the stairs instead of the lift
  • Parking farther away from your destinations
  • Engaging in hobbies and sports such as active yoga, dancing, gardening

Purposeful exercise

Purposeful Exercise - moderate to vigorous exertion
While the report concluded ‘there is no consensus on what types of exercises are optimal for brain health’, it recommended that for purposeful exercise, we follow the American Heart Association’s recommendation of 150 minutes of weekly, moderate-intensity aerobic activity, or 75 minutes of vigorous activity, and two or more days a week of moderate-intensity, muscle-strengthening activities.

These should ideally include a combination of:

  • Walking at a brisk pace to increase your heart rate
  • Strength/resistance training eg free weights, squats, lunges
  • Aerobic training which raises your heartrate eg cycling, jogging, running, swimming laps, group exercise classes

Furthermore, the experts behind the report advised challenging yourself a little bit more over time, for example:

  1. If you are not very active, start stretching and walking at a leisurely pace.
  2. If you are already a walker or jogger, increase your pace or distance.
  3. If you are an active runner, keep running and start strength/resistance training.
  4. To stay motivated, consider doing physical activities with other people. Social aspects of physical activity can help inspire you to continue your efforts.
  5. Make concrete plans to move your body – think about when, where and with whom you will be physically active.

The World Health Organisation adds that upping the amount of aerobic exercise to 300 minutes per week of moderate intensity or 150 minutes vigorous intensity will bring additional benefits.

During moderate-intensity exercise, your heart will beat faster and you’ll breathe harder than normal but you will still be able to talk. At vigorous intensity, you will probably get warm and begin to sweat and you won’t be able to talk much without getting out of breath.

Research Details

March 2021

Page Last Reviewed

March 2022

Next Review Date

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Erickson K, Hillman C, et al. Physical Activity, Cognition, and Brain Outcomes: A Review of the 2018 Physical Activity Guidelines. Medicine & Science in Sports & Exercise 2019; 51: 1242-1251

Erickson K, Hillman C, Kramer A. Physical activity, brain, and cognition. Current Opinion in Behavioral Sciences 2015; 4: 27-32

Erickson K, Leckie R, Weinstein A. Physical activity, fitness, and gray matter volume. Neurobiol Aging 2014;35: S20–S28

Erickson K, Weinstein A, Lopez O. Physical activity, brain plasticity, and Alzheimer's disease. Arch Med Res 2012; 43: 615-621

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Rabin J, Klein H, Kirn D, et al. Associations of Physical Activity and β-Amyloid With Longitudinal Cognition and Neurodegeneration in Clinically Normal Older Adults. JAMA Neurol 2019; 76: 1203-1210.

Sexton C, Betts J, et al. A systematic review of MRI studies examining the relationship between physical fitness and activity and the white matter of the ageing brain. Neuroimage 2016; 131: 81–90

Stillman C, Donofry S, Erickson, K. Exercise, Fitness and the Aging Brain: A Review of Functional Connectivity in Aging. Archives of Psychology 2019; 3

Stillman C, Erickson K. Physical activity as a model for health neuroscience. Ann N Y Acad Sci 2018; 1428: 103-111

Stillman CM, Cohen J, Lehman ME, Erickson KI. Mediators of Physical Activity on Neurocognitive Function: A Review at Multiple Levels of Analysis. Front Hum Neurosci 2016; 10

Tarumi, Takashi et al. Exercise Training in Amnestic Mild Cognitive Impairment: A One-Year Randomized Controlled Trial. Journal of Alzheimer's Disease 2019; 71: 421-433

The Brain-Body Connection: GCBH Recommendations on Physical Activity and Brain Health. Global Council on Brain Health 2016

 
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