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Physical activity and the brain - John Ratey and 'Spark'

John Ratey is a clinical associate professor of psychiatry at Harvard Medical School and an expert on neuropsychiatry. In 2008 he co-authored a book with Eric Hagerman, called Spark: The revolutionary new science of exercise and the brain. In it Ratey argues that ‘the point of exercise is to build and condition the brain’. (1) If this is true then it obviously has enormous implications for performance as well as mental health and feelings of well-being.

In Spark Ratey argues that human beings, like other animals, but unlike plants, have brains because they need to move to find food. This means ‘the relationship between food, physical activity and learning is hardwired into the brain’s  circuitry.(2) In other words, we are designed as human beings to be physically active and our modern sedentary lifestyle is not simply leading to obesity in both adults and children, but this inactivity may also be ‘physically shrinking’ our brains.


Ratey argues, as we shall see more fully below,  that physical activity is essential for good mental health but he is particularly interested in its importance for cognitive functioning.  Ratey’s work relies extensively on the recent research on the plasticity of the brain. ‘Far from being hardwired,’ writes Ratey ‘ as scientists once envisioned it, the brain is  constantly being rewired.’ (3) Exercise can improve learning ‘on three levels’:

First it optimises your mind-set to improve alertness, attention, and motivation; second, it prepares and encourages nerve cells to bind to one another, which is the cellular basis for logging in new information; and third, it spurs the development of new nerve cells from stem cell in the hippocampus. (4)

The hippocampus is the brain region primarily involved in learning and memory.

Learning difficult material is not enhanced during periods of physical activity – only once the blood flow returns to normal, after periods of physical exercise. Indeed Ratey tells us that this is an ideal time to undertake serious thinking or anything involving complex analysis. As we shall see more in a later section, for optimal learning, aerobic exercise is best combined with some complex skill acquisition as well such as dancing.

Since Rately emphasises the link between physical activity and learning, memory, concentration and mood he argues that being physically active can help academic performance. In an article on 'active play and cognition' Jacob Sattelmair and  John Ratey review some of the literature on physical activity and cognition/academic performance. They report that while some show a strong link between academic performance and physical activity others show little or moderate effects. However, they argue that the actual level of physical activity is vitally imporant. They write: "Physical activity predicts higher academic performance, but physical education with insufficient levels of activity does not.' (5) In other words to see benefits there must be  'sufficient duration and intensity of aerobic activity'. (6) The type of activity they  favour and the evidence from Madison Junior High School are covered in other sections.


Ratey reminds us that the word stress can be used to  refer to a whole range of feelings, from being challenged to being so wound up for a prolonged period that it can tip us into mental disorders such as anxiety and depression. Stress can also have a seriously negative impact on our bodies.

Ratey argues that we can’t grow and adapt as human being unless we’re stressed. It is stress that helps us develop physical and psychological resilience and the resources we need to overcome the inevitable difficulties in life. If we have small everyday stresses in our life, this keeps our system functioning properly and allows us to survive the bigger stresses which will come our way sooner or later.

Ratey quotes interesting research carried out by Dr Mark Mattson, chief neuroscientist at the National Institute of Aging in the USA. His work shows that restricted calorie intake through ‘meal skipping’ can prolong life essentially by stressing the system. Mattsons’ work also gives a different slant on why vegetables, like broccoli, are so good for us. The argument is usually made that vegetables are good because they contain antioxidants. But Mattson’s argument is that it is more because they contain ‘toxins’:

Many of the benefical chemicals in plants – vegetables and fruits – have evolved as toxins to dissuade insects and other animals from eating them. What they are doing is inducing a mild, adaptive stress response in the cells. For example, in broccoli there’s a chemical called sulforaphane, and it clearly activates stress response pathways … (7)

Ratey also points out the while mild stress is essential for optimal human functioning chronic stress is bad and really undermines the functioning of the brain. So one of the ways to help us cope with serious stress is to build some amount of daily stress into our lives and, according to Ratey, exercise is one important way to do this as it acts as a stressor. 


Ratey summarises research which shows the importance of physical activity to the prevention or treatment of anxiety. He sets out seven main reasons why anxiety may be reduced or eliminated with exercise:

  1. Taking part in exercise distracts from feelings of anxiety.
  2. Exercise can reduce muscle tension thereby allowing people to feel less tense.
  3. Being physically active builds brain resources through the release of varous hormones such as serotonin.
  4. Being physically active helps people cope with feelings of panic by getting them used to feelings of arousal. For example, the pounding heart which accompanies panic attacks can become less frightening as this is also a feature of exercise - a healthy activity.
  5. Exercise 'rewires your circuits' - it specifically prevents the amygdala, the fear centre of the brain, from 'running wild'.
  6. It improves resilience by learning 'self-mastery' - it puts people in charge in charge of their life and how they feel and this has a positive effect on feelings of self-esteem and self-efficacy.
  7. Exercise 'sets you free' by encouraging activity and movement.


Physical activty is important in counteracting depression, not simply because it can elevate endorphins - feel good hormones - but also because it 'regulates all the neurotransmitters targeted by anti-depressants'. Numerous studies, some outlined in another section, show how successful exercise can be in counteracting or preventing depression - often outperforming anti-depressants.

Ratey argues that a part of the problem in depression is that it 'shuts down learning' and can lead the brain to become inflexible and stuck in 'a negative loop of self-hate'. Indeed he argues that depression is almost as if the brain is going to sleep or hibernating. Exercise, on the other hand ...

... gets us moving, naturally, which stimulates the brain stem and gives us more energy, passion, interest, and motivation. We feel more vigorous. From above, in the prefrontal cortex, exercise shifts our self-concept by adjusting all the chemicals ... . And unlike many anti-depressants exercise doesn't selectively influence anything - it adjusts the chemistry of the entire brain to restore normal signalling. It frees up the prefrontal cortex so we can remember the good things and break out of the pessimistic patterns of depression. It also serves as proof that we can take the initiative to change something. This paradigm holds true for exercise's effect on mood in general, regardless of whether we're depressed or coping with  some nagging symptoms. Or even if we're just having a bad day. (8)

Other benefits of exercise

Ratey also devotes chapters in Spark to the link between physical inactivity to Attention Deficit and Hyperactivity Disorder and how addictions can be broken with the help of exercise. He also devotes time to the link between exercise and pre-menstrual and menopausal mood swings. He also argues that exercise can help ward off the cognitive and emotional decine which can accompany aging.


 1. John J. Ratey and Eric Hagerman,  Spark: The Revolutionary New Science of Exercise and the Brain, Little Brown, New York, 2008, page 3

2. Spark , page 3.

3. Spark, page 36.

4. Spark, page 53.

5. Jacob Sattelmair and John  J. Ratey, 'Physically Active Play and Cognition', American Journal of Play, Winter 2009, page, 369. 

6. Sattelmair and Ratey, page 369.

7 Matteson quoted in Spark, page 73.

8. Spark, page 135.

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