Transcriber: Maram Turkya Reviewer: Rhonda Jacobs
Imagine that you have a pill in front of you,
and that pill can make you more creative,
it can improve your energy,
it can improve your memory,
it can make you more tolerant to stress and make you more focused.
Perhaps it can even make you smarter.
Well, such a pill would sound too good to be true, right?
But there actually such a pill,
and it's called physical exercise.
Physical exercise has tremendous effects on the brain,
and the brain is one of the organs,
perhaps the organ,
that is most affected in a positive way if we move.
I think that all of you know that you will feel better if you exercise,
but what most people do not know
is that it will increase, basically, all of their cognitive functions -
memory, creativity, attention, it all gets better.
So let's look at one of those functions:
memory.
Now, the sad truth is this.
Memory shrinks as we get older; it gets physically smaller .
The red structures you see here is the hippocampus.
That's the memory center of the brain.
It has other functions as well, but it's very important for memory.
And we have two hippocampus,
one in the left hemisphere of the brain and one in the right.
Hippocampus reaches its peak size
when you're about 25-30; thereafter, it starts to shrink,
and does so by up to 1% per year for the rest of your life.
And that development has been thought to be inevitable;
there is no way to change this.
We have known that if you drink a lot of alcohol or use narcotics,
the hippocampus will shrink faster,
but to slow down the shrinkage has been thought to be impossible.
Until researchers in California started believing
that maybe this could be affected by physical exercise.
And why did they think about physical exercise?
Why didn't they think about crosswords puzzles or sudoku or something like that?
Well, they had seen that when you put a running wheel
into the cage of laboratory mice, the mice will start running on the wheel
and then they will form new brain cells In the hippocampus.
And they form lots of new brain cells in the hippocampus.
The hippocampus actually grows.
Now, those results were for mice.
Can you automatically assume that the same thing happens for humans?
No, you cannot, of course, you have to test it first,
and such an experiment has been made.
About 100 individuals were collected and divided into two groups.
One group that got to walk,
three times a week, 40 minutes every time, fast walk, they were not running.
The other group did stretching exercises,
three times a week, 40 minutes every time,
with a big difference that the stretching group
did not increase their pulse.
Now, this lasted for 12 months,
and the size of the hippocampus
was measured before this 12 month period and after it.
And when you measure the size of the hippocampus,
you do so by MRI scanning.
So what had happened?
Well, if we look at the stretching group,
their hippocampus had shrunk by 1.4% during the year.
It was 1.4% smaller.
which was a pretty expected result since it does shrink about 1% per year.
But what was very surprising
was what one saw when one looked at the walking group
because their hippocampus had not decreased in size,
but grown by 2%.
So instead of getting one year older,
it had gotten two years younger in terms of size.
Now, the yellow structures you see there, that's the hippocampus.
And you see the brain in the section like this, on this picture.
And the red line is the stretching group, where the hippocampus had shrunk,
and the blue line is the walking group, where the hippocampus had grown,
and you can see the same has happened in both hemispheres of the brain.
Now, when you see this, you may think: That doesn't matter to me.
I don't care how big my hippocampus is.
It doesn't affect my memory.
But actually it does.
Because this group, the walking group,
had not only gotten a bigger hippocampus,
they had increased their memory during this year.
Memory was tested with several different memory tests,
and the walking group had increased their memory,
especially when it comes to spatial memory,
the ability to learn locations and spaces
and finding your way around places,
whereas the memory of the stretching group was unaffected.
So it seems that it's possible to slow down or even reverse
the shrinkage of one of the most important parts of the brain
if you're physically active.
Now, this is just one in a long line of the astonishing results
that I've seen during the last years
when it comes to how physical activity affects the brain.
And these are some others.
Results on creativity tests increased by more than 50% the hour after walking.
Twenty minutes of physical activity
increased results on tests for reading comprehension.
That was for kids - that was testing in school.
And running increases our well-being so much
that it's actually comparable to antidepressants
for mild and moderate depressions.
How about this: Can it make us smarter?
Well, that would sound too good to be true, right?
Well, one of us actually tried to answer this during a long time,
and it's been very difficult to do so.
But actually data from Sweden was vital to give an answer
or at least an indication of an answer to this question.
What kind of data was that?
Well, up until about 10 years ago,
it was mandatory in Sweden
for all the 18-year-old males to do testing before the military service.
All 18-year-old males had to go to a military center,
do a cardiovascular test, do a strength test, and do an IQ test.
And when data was collected from 1.2 million Swedish 18-years-olds,
this is what one saw:
better cardiovascular fitness, higher IQ.
This is cardiovascular fitness on the x-axis,
where 9 is the best, and 1 is the lowest.
And as you can see, the better shape they were,
the higher intelligence they had.
Strength was not correlated to IQ.
Eighteen-year-olds that were strong had neither high nor lower IQ
than those that were not so strong.
All of this I think can be summarized into a very simple phrase,
and that is, the brain is built for movement.
The brain works better if we move.
But why is that?
That may seem very strange from our perspective.
But I think it's easier to understand if we take a step back
and look upon the history of humanity.
If we say that humanity is 1 million years old,
which is a time-frame that's often used,
you could argue it should be a bit longer or shorter,
but let's say 1 million years old.
Then this is how we lived up until 10,000 years ago.
We were hunters and gatherers on the savanna,
constantly moving, constantly chasing our food,
not being settled in one place,
and not farming the land to get the food and energy that we needed.
Then about 10,000 years ago, we became farmers.
And then 200 years ago, we became industrialized.
Now, during the last 20-30 years or so, we have become digitalized.
Now, these time-frames, they're so long,
that it's very difficult to get an understanding of them
on an intuitive level.
It's impossible to think of a world without the internet anymore.
And 200 years, that's an eternity.
And 10,000 years
is I think more of a theoretical concept than an actual timeframe.
So I think it is easier to understand if you look upon humanity's time
as 24 hours.
And if we do that, this how we have lived from midnight until 23:40.
And then we were farmers from 23:40 until 23:59:40 -
20 seconds before midnight.
And finally this.
(Laughter)
And actually we were industrialized first,
so we became digitalized 23:59:59 - one second before midnight.
If we look at other species in nature,
we see that evolution normally makes slow changes.
It takes ten thousands or even hundreds of thousands of years
before evolution makes major changes with a species,
and the same goes for us humans.
We have not changed in 10 or even 20,000 years.
If we could travel in a time machine 10,000 years back in time,
you would meet people who were like us,
had different language than us, of course,
and they had different experiences,
but they basically had the same brains as we have,
and the same mental capabilities, and mental possibilities as we have.
So biologically speaking, we 're still here.
And this is what has shaped us,
because this is how we have lived during the majority of mankind's 24 hours.
Now, what changes have we made
when we have gone from the savanna until our internet society?
Well, those changes are enormous, of course,
within a large number of areas, but one of them that we move less.
Now, how much less do we move?
Well, that's difficult to say exactly
because our ancestors did not have any activity trackers or step counters,
but it's at least possible to make a qualified guess
by looking at some of the people who still lives like hunters and gatherers.
And there a few of those on the planet,
among them the Hadza people in Tanzania.
They're one of the last groups that lives like hunters and gatherers,
and they walk about 11 - 12 km every day.
They take between 15,000 - 17,000 steps.
How about farmers?
Well, then we can look at Amish people in the US.
They live in Pennsylvania and Ohio,
and they've chosen to live without electricity.
They don't have TVs or phones or internet,
and they live in a traditional farming society,
and they take about 18,000 steps per day.
This can be compared to us in the Western world,
where we take somewhere around 7,000 steps per day.
So what we can conclude is that we've made a huge difference
in terms of how much we moved.
And we have made that difference in a relatively short time.
Perhaps we've cut it by half - the amount of movement that we get,
when we have gone from the savanna until our society.
And we have done that in a time that is so short
that biologically we haven't changed;
biologically we're still here.
If we combine this with the fact
that physical activity makes us more creative,
improves our memory, makes us more focused,
and perhaps even smarter,
then we realize that a lot of people in today's society
could probably function better mentally
if they just took the time to move more.
And if we combine this with the fact
that physical activity makes us less stressed,
and less anxious, and less depressed,
then we realize that some of the mental health problems
that we see in today's society
may be due to this -
not all of them, of course, but some of them.
And some of them can definitely be treated with this.
In this evolutionary context,
I think a lot of the effects on the brain makes a lot more sense.
If we assume that we're still back here biologically, which we are,
and then we ask ourselves the question,
Why do we feel better if we exercise?
Well, our ancestors, they didn't run to go for the marathons.
They ran to catch food, to avoid predators,
to find new lands where they could settle.
All these things meant that they increased their chances of survival.
And the brain will reward us with more dopamine and a pleasant feeling
when we do things that are in line with increased chances of survival.
That's the mechanism that we tap into today while we go jogging.
The brain thinks that we're actually running for our lives
when we're running today.
Why is memory improved?
Well, that maybe due to the fact
that when our ancestors ran
during hunting and discovering new land and so on,
they saw new things.
They saw a new environment,
they experienced new things during hunting,
and then it makes sense for the brain to increase memory somewhat
because there's new important information incoming.
"I better remember this."
If we just sit in one place,
the brain will interpret that as nothing new is happening.
Because the brain has not been developed
to have information passively from phones or tablets.
It will think that nothing new is going on while we sit in one place.
Why is focused increased?
Well, that may be due to hunting.
When our ancestors ran during the hunt,
increased focus was probably an advantage.
The one can establish the most focus during the hunt
is probably the one catching his or her prey.
So in this evolutionary context, I think a lot of the effects on the brain
makes more sense.
And it's easier to understand why evolution has tailored our brain
in such a way that it benefits so much from physical activity.
This is something that I've thought a lot about.
If it's so good for us, why don't love it?
Why isn't it the best there is?
Why this actually the best there is?
Because this is the best, sitting in front of the TV.
Well, I think you can understand that also from an evolutionary perspective.
We have had a shortage of calories for almost our entire history.
Calories have been very hard to get by.
If our ancestors were lucky to find sweet berries on the savanna
or honey or something that contained a lot of calories,
they should feel the urge to eat it all.
Eat every last berry because tomorrow may be these be gone.
Then someone else has taken them, and tomorrow I may not find any food.
That crave for calories is very functional
in a world were calories are hard to get by.
But that crave for calories does not make a lot of sense
in a world full of fast-food restaurants.
When we take that crave for calories that evolution has built into us
during millions and millions of years where calories are hard to get by,
until today's society where calories are basically free,
that's when you get the problems
that you see with diabetes and overweight and so on.
The amount of energy that we have in our bodies
is not just dependent on how much energy we put in ourselves,
such as food, but also how much energy we use.
And that is, I think, why we have this drive to stay in the coach,
to not waste your valuable calories.
Don't waste your energy.
That explains the paradox why it's so important for the brain to move,
but at the same time, we're basically lazy.
If I would have been you and I had heard all of this,
I would probably think that "This must be exaggerated.
If this was the case we would have known about this.
And I think the answer to that is this:
We've always known about this.
This is Hippocrates.
He's considered the father of medicine, and he said 2,500 years ago,
''Walking is man's best medicine.''
He could have added "woman's" here,
but apart from that, this is very much to the point.
He knew this without any research report or MRI scanners or anything like that.
We've always known this, but I think we have forgotten about it
during the last 150 years.
And the reason for that is, I think,
that we've had such a tremendous medical development
during the last 200 or 150 years.
All the things that you take for granted in medicine:
MRI scanners, vaccines, X-rays, antibiotics,
basically all of them has seen the light of day
during the last 150 years.
And that phenomenal development has pushed this old knowledge to the background.
And a way to illustrate that is this, I think.
Which one doesn't fit here?
Without thinking too much.
The MRI scanner, the da Vinci Robot, this cancer seeking molecule, or these.
Of course we take away these,
because they remind us of the fitness industry.
There's nothing wrong with the fitness industry,
but we don't attach any medical value to it.
That's the kind of mistake we make over and over again.
We think that something as simple as these
cannot be worth as much as all of these technologies
that billions and billions of dollars has been put into.
But actually, they can.
And I would say that this one beats them all, actually.
And a lot of the findings on how the brain is affected by physical exercise
has been done with MRI scanner.
And it's almost an irony, I think,
that one of the most advanced medical technologies we have
is now helping us rediscover
one of least advanced or most simple medical technologies,
namely these, or whatever you like to put on when you go exercising.
I sometimes get the question: ''What does exercise mean to you?''
And this is how I see it.
It's a step back to the lifestyle that we have been developed for.
So forget about your association to sports.
Exercise is about something much more fundamental than that.
And not only is it a way to optimize the body,
but it's also a way to optimize the brain.
Thank you so much for listening.
(Applause)