Exercise and the Brain

The human race is now more inactive than ever. In 2016, nearly 40% of Hong Kong adults could be classed as overweight or obese and, even more worryingly, around 20% of all primary and secondary school children.

Most of us are aware that inactivity, coupled with the constant stressors of a hectic lifestyle and poor sleep, missed meals, and diets high in alcohol and convenient but poorly nutritious food that does nothing much for our bodies other than provide calories, ultimately leads us to gain excess body fat… Most of us also don’t need reminding that carrying excess body fat can increase our risk of diseases such as type 2 diabetes, coronary heart disease and even some cancers. Not good.

These are all pretty negative consequences for the body, but what about the negative effects on our brains?

Or, to look at it from a slightly more positive angle, what are the positive effects of exercise on our brains?


John Ratey MD, a psychiatrist who has dedicated much of his career into researching exercise and how it affects the brain said:

“Exercise is the single most powerful tool you have to optimise brain function… exercise has a profound impact on cognitive abilities and mental health”

So why is this?

Simple things first, even gentle exercise increases our heart rate and blood pressure, optimising the flow of oxygen rich blood to all of the body’s tissues, including the brain. There have been some fascinating studies looking at brain scans performed in sedentary and active individuals – the increase in nourishment to the brain tissue from the dramatic increase in blood flow is actually amazing. More oxygen means more fuel, which ultimately means more alertness and increased focus. Without adequate oxygen, brain cells will gradually wither away over time. Truly use it or lose it.

Secondly, when exercising, our brains naturally produce more of the same “happy” chemicals (serotonin and dopamine) that many of the first-line anti-depressant medications try to increase the levels of too. Exercise has been shown to be an acceptable method of treating, and then keeping away, mild to moderate depression in studies, increasing focus, motivation and mood overall. Makes sense really! This is coupled with the added benefit of increased self-esteem as your body starts feeling and looking fitter and stronger and a sense of accomplishment when fitness goals are achieved. And (as an extra little bonus from nature) this sense of accomplishment is interpreted by the brain as a type of “reward” which further activates the dopamine pathways in the brain… Basically making us want to continue to get our sweat on! With persistence, getting your active hours in eventually becomes the normal habit of daily life that it should be. We are made to move!

Finally, there has been some interesting research in the last few years which has suggested that increased activity levels increases the levels of a substance called ‘Brain Derived Neurotrophic Factor’, or BDNF. The aforementioned John Ratey MD calls it “miracle-gro for the brain”. BDNF is a chemical that basically appears to help us to create new “circuits” in our brain, whilst also helping us to preserve the ones we already have. This effect seems to be especially prominent in an area of the brain called the hippocampus, which is responsible for converting short-term to long-term memory (i.e. learning). More research is being done into this area, but it looks as though an increase in BDNF can increase mental performance, and it also therefore looks promising that exercise and activity could play a part in off-setting the onset of dementia.

Obviously these benefits will spread age-wide, but what about the kids amongst us specifically? Studies have been performed looking into how exercise and fitness levels relate to academic performance and have shown that the more active and ‘fit’ kids are, basically the better they seem to do at school and the better they perform mentally even into adult life. Is there any specific form of activity that is best for kids? Nope! Let them enjoy as many different things as possible, so long as they are getting a sweat on, getting out of breath and having fun for an hour a day – perfect. And for those of us over 18, the current exercise guideline is 150 minutes a week of moderate intensity activity (breathing somewhat harder and getting sweaty).

In summary, being active daily has more benefits than just improving the stamina and strength of our bodies and helping to shift excess body fat – we are made to move and keeping our bodies and, therefore, brains active and healthy from as young an age as possible can enhance our daily mental performance, happiness – and even offset dementia.


This article was written by Dr. Emma Warner, a British trained medical doctor Emma is currently in Hong Kong working with Joint Dynamics in the area of Personal Training.  Check out some of the work she’s been doing with us here….MEET EMMA