Does being physically fit make you smarter?

Does being physically fit make you smarter?

In considering the merits of this claim, I will be referencing the work of thought-leader Dr. John J Ratey, MD. John is an Associate Clinical Professor of Psychiatry at Harvard Medical School, is a Research Synthesizer, Speaker, Author and a Clinical Psychiatrist. His most recent book is the bestseller “Spark: How exercise with improve the performance of your brain” and his website is

The Malleable Body

 We all know that exercise is good for the body, doing more of it, in general, makes us incrementally stronger, flexible and durable. Fitness is a continuum, not a destination. Meaning that starting it, or doing more of it this month than last month, on the whole, means we move in the right direction along the continuum.

In this way the body is malleable, (most) of us can choose how parts of it are formed (or re-formed) and how it can perform.

Trying to hold the plank position for more than 30 seconds feels almost impossible the first time you do it, but practice it everyday for a month and you may even be able to complete the 5 minute challenge on Tribesports.

The Malleable Brain

brainaurora3_1038What, then, about the brain? Over the past fifteen to twenty years there has been a revolution in the thinking about the brain, and how malleable it is.  Long considered ‘hard-wired’ after adolescence, it is now scientific orthodoxy that the brain is constantly adapting to its environment; its billions of neurons constantly interconnecting, disconnecting and reconnecting with each other via trillions of synapses; far from being an immovable object it is unlikely to ever have the same configuration from millisecond to millisecond.

This immense complexity is only made more mind-boggling by the considerations that computational processes may operate at the synaptic (rather than the neuronal) level and that neuronal connections are different from connection to connection, and even change themselves over time, altered by such considerations as the level of myelination of the axonal sheath or the operation of neurotransmitters and modulators.

What’s more, if a sufficiently large set of neuronal-sequences reconfigure for a sufficiently long length of time, and/or with sufficient frequency, then this can lead to anatomical changes in the brain. Recent research has shown that London cabbies have a bigger hippocampus [link ] than us less-spatially aware mere mortals.

It’s no surprise that many have suggested that the human brain is the most complex thing in the universe.

These sequences – maps in time and space – that the networks of neurons make up are the brain’s representations of the outside (and inside) world. Some maps have been around for a long-time and are virtually immovable (your map of what a human looks like), some have been around a long-time and are hard to move (your idea about whether you should put your elbows on the table at dinner), and some have been around for just a short time and are very changeable (your thought about whether to have a snickers bar before lunch).

What is key here, is that ‘hard to move’ doesn’t mean ‘impossible to move.’ If you want to change something as ingrained as an attitude, or a trait, you can do it. It just takes work and the right kind of training.

So, how do we get smart?

 It seems being smart is no more or less than the ability of your neurons to make new connections in an efficient manner. As Dr Ratey says:

“It’s all about communication. Everything we do and think and feel is governed by how our brain cells, or neurons, connect to one another. What most people think of as psychological make-up is rooted in the behaviour of these connections. Likewise, our thoughts and behaviour and environment reflect back on our neurons influencing the pattern of connections.”

 The nature of any particular neuronal connection determines whether a package of information – an action potential – is passed from one neuron to the next. Chemicals called neurotransmitters carry the message through the synaptic space (the space between one neuron’s axon and the receiving neuron’s dendrite) – and, depending on a number of factors, including the number and type of neurotransmitter, the number and type of post-synaptic receptors and the frequency of activity determines whether the receiving neuron will be excited enough to fire off its own action-potential. And, as Dr Ratey states:

 In general terms, the more often a set of neurons fire together, the more likely it is they will wire together. “

 And when a set of neurons have wired together – they have formed a representation of something. They have learned.

Yet, as Dr Ratey explains, this is not the whole story:

 “As fundamental as neurotransmitters are, there’s another class of master molecules that over the past fifteen years or so that has dramatically changed our understanding of connections in the brain – specifically how they develop and grow.

 Whereas neurotransmitters carry out signalling, neurotrophins such as brain-derived neurotropic factor (BDNF) build and maintain the cell circuitry – the infrastructure itself.”


So it’s the significance of BDNF that is – as Dr. Ratey points out – the revolutionary idea:

“We’ve known for a while that BDNF causes the sprouting of new neuronal branches, so that new connections can be made, but we now also know that BDNF binds to receptors at the synapse, immediately improving signal strength.  Inside the cell, it activates genes that call for the production of more BDNF as well as serotonin and proteins that build up the synapses.

 BDNF both directs the traffic and engineers the roads.”

 In other words, if we learn by having ever increasing neuronal connections, then we need to ensure that there is a robust infrastructure supporting those connections. And that is where BDNF is fundamental.

Physical Exercise and Brain Performance

But, you ask, what has this to do with being smart and (physical) exercise?  Surely if I want to become smart I just do loads of studying and brain-training exercises and all that, right? I don’t just run around the block, and I’m an instant Einstein, right?

Well, yes – and no – maybe we are making a category error when we make a separation between moving and thinking; after all when we move we are still using our brain, as Dr Ratey explains:

When we exercise, particularly if the exercise requires complex motor movement… we’re causing the brain to fire signals along [a] network of cells, which solidifies their connection.”

 In other words, the same general mental processes are involved in moving as they are thinking. As Dr Ratey states:

“As our species has evolved, our physical skills have developed into abstract abilities to predict, sequence, plan, rehearse, observe ourselves, judge, correct mistakes, shift tactics, and then remember everything we did to survive.”

And Dr Ratey references and very interesting quote from neurophysiologist Rodolfo Llinas’s 2002 book, I of the Vortex: From Neurons to Self:

 “That which we call thinking is the evolutionary internalization of movement”

At a fundamental level, then, thinking and moving are part of the same continuum. And moving came first. And because moving came first, in doing it we are booting-up the ancient machinery that has made our species so successful. And in doing more of it we really get that ancient machinery firing – and in doing less of it we let it rust.

In doing more of ‘moving’ we produce more BDNF. In fact, in doing more of ‘moving’ with increasing intensity we produce more and more of BDNF.

But, Dr Ratey doesn’t ask that we just take his word for it, in his book details lots and lots of experimental evidence that proves it is the case.

Being physically fit makes you smarter.


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