Evidence is growing that regular exercise improves not just physical health but brain function and mental wellbeing. And we don’t have to become gym bunnies to benefit. By Ruth Nichol.
Unlike our closest relatives among the great apes, we can’t get away with spending our days lazing about doing nothing more strenuous than plucking the occasional piece of fruit from a tree.
We may share 99% of our DNA with them, but animals such as gorillas and chimpanzees can spend up to 20 hours a day resting, eating, grooming and sleeping without getting fat or suffering any of the health problems that plague modern humans, such as heart disease and diabetes.
Nor do they experience much in the way of anxiety or depression – at least when they’re living in the wild.
As much as we would like to loll about in a similar fashion – and we have used our superior brains to engineer our lives so that most adults now spend 70% of their time either sitting or lying down – we’re paying the price in terms of poor physical health and an epidemic of mental illness.
“We’re now at a point where we can order food, we can date, we can entertain ourselves without having to move a muscle – we don’t even have to get up to change the channel on the television any more,” says British science writer Caroline Williams.
In her recent book, Move! The new science of body over mind, she says our increasingly sedentary lifestyle means that as well as declining physical and mental health, we’re also weaker than we used to be. An American study of students aged 20-35 published in 2016 found that men’s grip strength had fallen over three decades, with Millennial males able to exert just 44.5kg of force compared with the 53kg their fathers could exert in the same test in 1985.
That in itself is likely to be a contributing factor to growing levels of mental ill health.
“The link between physical strength and anxiety and depression is just so strong,” says Williams. “That research has been around since the 1980s and you really can’t argue with it.”
IQ reversal
We seem to be getting more stupid, too. Recent studies have found that after decades of rising IQs (known as the Flynn Effect, after the University of Otago professor the late Jim Flynn, who first observed the phenomenon in the 1980s), IQs among young people are starting to fall – what’s known as the Reverse Flynn Effect.
Our levels of creativity are also falling. “One study from researchers at Stanford University reckoned that ideas were becoming harder to come by, that there were fewer creative ideas coming through than previously,” Williams says.
And although our sedentary lifestyle is unlikely to be the only contributing factor to these changes, she believes it is an important factor. “It’s a major lifestyle shift that has been happening. We’re losing this way of regulating our emotions, this way of protecting our brains from decline.”
Brain-movement link
That’s because, according to research by David Raichlen, who studies human evolution at the University of Southern California, changes in our brains that began four million years ago mean physical activity is essential for our physical, mental and cognitive health. That’s when our ancestors stopped being ape-like animals who sat around in trees all day eating fruit, and started to explore. Over the next million years or so, they evolved to became hunters and gatherers who walked upright in search of food – and their brains became even more dependent on movement to function well.
“If you think of it in terms of hunter-gathering, we needed to be able to think better because we’re quite puny animals; we’re not that fast and we’re not that strong,” says Williams. “And so to survive we needed to be able to work together and to plan ahead and outsmart animals and navigate all these kinds of things.”
The result is an inextricable connection between physical activity and what happens in our brains that goes well beyond producing feel-good hormones such as endorphins. The fact is, says Williams, we weren’t born to be still. And, as she discovered when she started talking to scientists working in this area, there is now a rich body of research that helps explain why moving the body is so important for the brain and the mind.
As Raichlen puts it, we are “cognitively engaged endurance athletes”.
His research suggests that our physiology became fixed so that, when we exercise, the brain responds by physically adding more capacity.
“Physical activity stimulates the brain to make new connections, more blood vessels, more blood, more brain cells, and the whole thing just works better when we’re active,” says Williams.
It follows, then, that the way to reverse the decline in our physical, mental and cognitive health is to start moving more. The good news is that doesn’t mean signing up for regular HIIT classes (high-intensity interval training) or lifting weights at the gym.
Both those activities are better than doing nothing, says Williams, but it’s more important to reintroduce the incidental movement that has become lost from many of our lives. That means doing things as simple as putting down our devices, getting out of our computer chairs, and taking regular breaks so that we move around more. Carrying our own shopping rather than accepting an offer of help or getting it delivered, doing gardening, or even cooking a meal rather than ordering takeaways can all increase how much we move.
“The real change we need to make is not necessarily shoehorning in more exercise but breaking down the amount of time we spend sitting. It’s good to make a conscious effort to do more physically for yourself. It doesn’t have to be complicated. It just has to be more of a habit.”
As Williams points out, people from what are known as “blue zones” – societies whose members live longer, healthier lives, with less dementia and fewer mental-health issues – don’t work out at the gym.
“They just have more movement as part of their everyday life, which admittedly is harder to do if you’ve got an office job.”
On the Japanese island of Okinawa, for example, a blue zone where people are 40% more likely to reach the age of 100 than in other parts of Japan, everyone eats at low dining tables, which forces them to maintain lower body strength well into old age.
“Older people are constantly hopping up and down from the floor, and we know that leg strength is correlated with all kinds of long-life benefits. Essentially, every time you stand up off the floor, you’re leg-pressing your entire body weight. Do that several times a day and you don’t need to go to the gym.”
As she explains in the book, the Hadza – a group of modern hunter-gatherers in Tanzania who live more or less as our ancestors did – don’t do formal exercise, either. The men walk an average of 11km daily, hunting with bows and arrows and climbing trees to collect honey. The women walk around 6km and dig for tubers using a sharpened stick.
“It’s not easy work, but it’s not a HIIT session, either,” she writes.
One study found that the Hadza use roughly the same number of calories a day as the average Westerner, but they use them more efficiently. Another study found they live as long as we do, and are both healthier and happier.
“Low-level, all-day movement seems to be close to the ideal scenario for both body and mind – keeping the mental and physical cogs oiled, and blood, lymph and all our other bodily fluids moving on the inside in ways that support thinking, feeling and moving.”
Move! outlines six areas we can concentrate on to introduce more movement into our lives: walking, building strength, dancing (see “Rhythm of life”, previous page), working the core — including having an upright posture (see “Shoulders back!”, page 20) — stretching and deep breathing.
The sweet spot
Walking is the first obvious area to start making changes. There’s continuing debate about exactly how much we should walk each day – it turns out the much-touted goal of 10,000 steps was probably plucked from a Japanese advertiser’s mind.
But more walking is definitely better. The Hadza people walk between 8000 and 15,000 steps a day, and Williams says that’s a good target to aim for.
“If you don’t get to that, it’s not terrible, but people who are averaging two to three thousand steps a day should increase that. However, if you’re getting seven to eight thousand, you’re probably fine – if you’re doing two half-hour walks a day you’re probably not far off that figure.”
Ideally, we should walk at a brisk pace – about 120 steps a minute. “That is like a sweet spot where your heartbeat synchronises with your step rate and it gives a boost of blood to the brain – which might help explain why a brisk walk perks you up.”
But if a brisk pace isn’t always your bag, there are also advantages to walking at a more leisurely pace. That’s because meandering seems to switch off activity in the pre-frontal cortex, whose role is partly to act as a brake on fanciful, “outside the square” thinking. Switching this process off can boost creativity.
“It’s an easy way to put the brain into the right zone. Some of our greatest thinkers would wander the hills and think big thoughts, but we’re not doing that any more. So, walking is like this multi-use tool for getting the best out of your brain.”
Mood-altering hormone
Simply being upright – and thus working against gravity – seems to be an essential part of the process. One of the more surprising research findings Williams reports on is that putting weight on our bones makes them release a hormone called osteocalcin, which plays an important role in brain health. “It goes into the blood and talks to the brain and improves memory, and it has a role in reducing anxiety as well. So, it’s like this mood-altering, mind-altering hormone that is only released if we put weight on to our bones and challenge them as part of the bone-building process.”
Some studies have found a link between low levels of osteocalcin and Alzheimer’s. Others have linked the loss of bone mass seen in osteoporosis to an increased risk of cognitive decline. Astronauts also seem to suffer short-term cognitive problems after a gravity-less stint in space, as do people who have experienced prolonged bed rest.
“It is now emerging that these things are very much connected by one strange and surprising fact: our bones are in constant conversation with our brains,” Williams writes. “What they talk about depends very much on how much we ask our bones to move while also resisting the pull of gravity.”
Williams has found that the rate at which we breathe also has a sweet spot. Humans are the only species that can control the rate of their breathing, something that seems to have happened in order for us to be able to speak. This helps control our brainwaves, which range from the high-frequency Gamma waves associated with problem-solving and concentration to the slow Delta waves of sleep.
Slow, deep breathing can help boost Alpha brainwaves that are associated with being relaxed and reflective. It seems that taking six breaths a minute favours Alpha brain waves, which help calm down the nervous system and also puts the brain into a more relaxed state.
Interestingly, studies have found that relaxing activities such as reciting the rosary in Latin or chanting Eastern chants or doing yoga put our breath into a rhythm of about six breaths a minute.
“This is something that we seem to have worked out as a species, sort of by accident. Breathing at six breaths a minute is, to all intents and purposes, a shortcut to a sense of calm and contentment.”
But whether you’re reciting the rosary, doing yoga or simply sitting in a chair while you practise slow breathing, it’s important to breathe through your nose rather than your mouth. That seems to be because breathing through the nose allows air – and information – coming in from the outside world to pass over the sensory neurons in the olfactory bulb, creating a nose-to-brain hotline.
These days, Williams makes a conscious effort to move more during the day. Having a dog helps, but rather than sitting at her desk pondering a difficult writing problem, she no longer feels guilty about getting up and going outside to do a bit of gardening, or taking her dog for another short walk.
Through her consultancy work with British companies, she’s also started spreading the word about the importance of moving, and helping them to create more movement-friendly workplaces.
“It’s about changing the culture in a way that makes managers aware that this is a good thing to do and to make it okay culturally. I want to help make people aware there are good reasons for moving more and not chaining people to their desks. We need to change this culture that says sitting at your desk is the best way of thinking and the best way of being – it’s not, and it makes people miserable.”
Rhythm of life
Humans are one of the few species who dance, and while some of us would rather poke our eye out with a stick than dance in public, we’re fighting against an instinct that is hardwired into us from the day we are born.
“Rhythmic movement is very much part of what makes humans tick,” Caroline Williams writes in Move!
In fact, dance is so hardwired into us that, left to our own devices, we all dance at the same speed – about 120 beats a minute. This is the case no matter how tall we are – and it’s probably no coincidence that it’s the same speed that hits the “sweet spot” when we are walking.
“It’s like our natural rhythm, which sort of blows my mind a little bit.”
As it happens, 120 beats a minute is the dominant rhythm in a lot of pop music. And the way we dance to pop music is very similar to the way people from other cultures dance to different kinds of music – stamping our feet on the floor while punching our hands in the air and nodding our heads in time.
“If there is one form of dance that you could do anywhere in the world without looking too out of place, this is surely it,” writes Williams.
Dancing can serve a similar role to brisk walking in boosting blood to the brain. But dancing can do other things, too. While jumping about in the kitchen on your own to pop greats like Stevie Wonder’s Superstition – judged the most danceable tune out of 148 played to student volunteers in a University of California experiment in 2012 – will make you feel good, so will dancing together with others.
In fact, moving in time with others – even at a more sedate pace than that of the average pop song – seems to be good for our souls. Williams says this is probably because it helps blur the lines between us and the people around us. That in turn draws us together emotionally and physically and makes us more likely to co-operate with each other.
Toddlers who are bounced on someone’s knee in time to music, for example, are much more likely to pick up something that has been dropped onto the floor and hand it back than toddlers who are bounced in a non-rhythmic way.
“There’s something about moving in time with other people that makes us feel closer together and makes us care more about each other.”
Shoulders back!
It turns out our teachers and parents were right: standing (or sitting) up straight is good for us, though not necessarily because it makes us look less slovenly.
Experiments by Elizabeth Broadbent, professor of psychological medicine at the University of Auckland, have found that sitting or standing with an upright posture makes us feel less stressed in situations such as giving an impromptu speech to strangers.
She and her colleagues have so far published three studies looking at the role of posture in the way we deal with stress and it’s clear that sitting or standing up straight helps promote a more positive attitude and reduces our anxiety.
In one experiment, which involved preparing and giving a short speech while walking on a treadmill in either an upright position – with shoulders back and looking straight ahead – or hunched over and looking at the ground, the upright walkers reported feeling more alert and marginally more confident and in control than the slouchers. They were also found to have lower blood pressure and lower skin temperature, both of which tend to rise when we are feeling stressed.
“It does seem that the posture you’re in alters your physiology and it alters the feedback in your body,” Broadbent says.
She first became interested in the importance of posture when she noticed that her own mood often lifted if she straightened herself up and put her shoulders back while out walking. She wondered if this was the case for others and embarked on research that has found that other people do, indeed, have a similar response.
More recently, she and her team have looked at the role of posture on memory, as well as how looking down at our mobile phones while we walk affects our mood. Both studies have been submitted to academic journals but have not yet been published.
No one has come up with an explanation for why posture helps regulate stress. Science writer Caroline Williams suggests some undiscovered link between engaging the core and what happens in the brain may hold the key. Broadbent suspects the reason is likely to be more complicated. But she has no doubt that changing our posture is a useful way of changing our mood.
“If you’re in a stressful social situation and want to feel more confident, more alert and more positive, then standing upright, putting your shoulders back and lifting your chin can definitely help.”
Move! The new science of body over mind, by Caroline Williams, Profile Books, $29.99.
This story was first published September 2, 2022