18 Aug 2019

Shane O'Mara: walking can help combat depression

From Sunday Morning, 8:41 am on 18 August 2019

Walking outdoors gives our bodies a range of benefits and can even help to combat depression, neuroscientist Shane O’Mara says.

Prof O'Mara is an avid walker who has just released a new book that is something of a hymn to the most basic of exercises, In Praise of Walking. It talks about the science of how we walk and why it's good for us, which invites us to marvel at the many substantial benefits it confers on our bodies and minds.

While in his book he cites studies and evidence that shows walking can help to combat depression, he says it’s not quite the same for anxiety.

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Photo: pixabay

“That’s a really new finding. Anxiety results from things that may be happening to you, so you have rummaged into thoughts that you find maybe are a little hard to escape from and these may be anxiety provoking.

“Whereas depression affects a much wider range of things than just the immediate contents of cognition – it affects how you feel, how you interact with others, how you experience pleasure, your levels of motivation.

“The evidence on that side, to my mind, is pretty impressive, that those who walk are at much lowered risk from suffering a depressive disorder than people who don’t.”

While looking at the brain as an electrical entity, research has found that Theta waves have popped up in movement analysis, he says.

“If you look carefully at these recordings, what you see is they come in at different frequencies and they tend to cluster at different frequencies and the one that pops up during movement, in humans and animals, most consistently is one called Theta.

“It happens about four to eight times a second while you’re moving … and the marvellous thing about Theta is that it engages electrical activity across the whole of the brain and it seems to be preferentially present during learning. So there’s some important relationship between Theta being present and learning and memory happening in the brain.”

The parts of the brain that are responsible for memory, learning and cognition, are the same ones that are badly affected by stress and depression. So if thinking improves then stress and depression will lessen or will be better tolerated, Prof O’Mara says.

In the book, Prof O’Mara notes studies that have shown walking helps with memory and how cells that "fire together, wire together".

“One of the great discoveries of the last 20 years … is that lots of regular exercise that pushes the body causes the release of a molecule in the brain called BDNF (brain derived neurotrophic factor),” he says.

“It’s a kind of fertiliser for our brain cells, it keeps them healthy, it keeps them alive, it keeps them talking to each other, it strengthens the communication between brain cells and it seems to be preferentially produced during Theta, so the electrical activity and the molecular activity in the brain are not separate, they’re kind of related to each other.

“Lots of this kind of activity is really good for the heart, but it’s also really remarkably good for keeping your brain in tiptop order.”

Another study that tracked adults’ personality change over a long period, found that the group that moved and walked the least showed a variety of malign changes.

“They became more disagreeable, for example, in terms of their interaction with others. I think this is just one of these other findings that backs up the general idea that movement is good for us, and sitting around doing nothing or sitting around and just watching the TV is bad for us.”

However, figures in New Zealand show that the average office worker takes only about 3000 steps a day. From smartphone and wearable device data, O’Mara says that different countries have been shown to have different walking step averages depending on the environment and lifestyle.

He says Japan, for example, tends to have people who walk the most in the world, about 5500-6000 steps a day, with cars being difficult to drive around the crowded cities and towns. In comparison, Saudi Arabia, where it tends to be hot and less busy, people average about 3000 steps per day.

“Anything up to maybe 15,000 or 17,000 steps per day is super and beyond that you’re not going to get any gain and probably not too much in the way of really great gains from anything above 12,000 or 13,000 steps a day.”

A good guide is to do between 10,000 and 12,000 steps, O’Mara says.

“I think if you want to get a really good effect on your heart, what you need is to do be doing something around about 5.5km or 6km an hour [in terms of speed] and keep that up to 30 minutes or 40 minutes, five or six days a week.”

O’Mara says he’s trying to get people used to the idea that the short burst of activity at a gym is not enough.

“What we really need to do is look at the balance of activity across the rest of your day, which we should be engaged in moderate levels of activity right across the day with the occasional burst of high intensity activity.”

And it’s never too late, he says, once you start to get in the habit then the benefits accrue quickly.

“They can be really quite profound, and if you keep it up for a long period of time, you can start to the changes become visible in terms of the structure of the brain.”