What does exercise do to the brain?

23 June 2014

Question

What effect does exercise have on the brain?

Answer

Hannah - And that links in really neatly with the question that Sherburne de Garmo has been in touch with saying, "What effect does exercise have on the brain?"

Martin - I can talk I think reasonably about what the effect of exercise on mood because I very often say to people, if you're feeling low or feeling anxious, feeling kind of under stress, get some exercise because we know it has profound and evidence based of effects on mood. Whether it's walking or cycling, I think that's one of the profoundly hopeful points out of all this, that actually, the brain probably is not a fix structure. Moods aren't fixed. They're fluid and it's very hopeful because we can do a lot ourselves to change them in a positive direction.

Hannah - What effect exactly does exercise have on the brain? So, Martin mentioned increased oxygen to the brain and that can obviously be quite helpful to keep those nerve cells functioning optimally. But what other effects can exercise have?

Katie - We often think of exercise as just to keep fit and keep the rest of the body healthy, but it does have quite have big effects in the brain. It's been implicated in what we call neurogenesis and that's the ability to actually grow new neurons inside the brain, in the hippocampus, which is heavily, heavily implicated in learning and memory. There are some experiments on mice by Professor Rusty Gage and he looked at mice in cages with running wheels and without. The mice that had access to these running wheels actually grew lots of new cells in the hippocampus and this finding has been extended to humans. So, a lot of neuroscientists will now jog. In terms of mood, actually there's evidence that exercise can help speed up recovery from depression and it's associated with a good mental health as people age. To some extent there's some evidence that it can increase the availability of serotonin and nor-adrenalin so chemicals in the brain that are implicated in mood. As a lot of people know then that exercise stimulates the endorphin release. These are chemicals and when they're released, they bind to receptors in the brain and the subreceptors that they bind to revolved in pain signalling and they actually disrupt pain signals that you get. And so, they would reduce some of the feelings of pain that many of us get when we exercise hard. Whether that's actually about the 'feel good' that you get from exercise or whether that's it, it takes a weight in the pain and you even can then benefit from the stimulation of some of the other chemicals like the serotonin in the brain isn't quite clear.

Hannah - Exercise can flood your brain with feel-good factors and increase the number of brain cells that you have and help with your learning memory. And also, I found a paper where stress exposure which causes lots of release of this stress hormone cortisol, you can become resilient to that via exercise because exercise will increase this brain derived neurotropic factor, BDNF which helps protect against the cortisol stress effect or at least in mice any way. It increases your resilience, that's nice. But what about the fact that if you're feeling low, if I'm feeling low, the last thing that I feel motivated to go and do is go out for a jog and I love jogging most of the time. So, how can you motivate yourself to go out and get this brain-boosting kind of positive effects of exercise?

Liz - Basically catch-22 and it is exactly that. You know, when you're in that place, you can't move. You just can't get out of the room, you can't get off the chair, let alone, go for a jog. Unfortunately, that really does come down to the individual person. I mean, beyond having an app that bleeps at you or a phone that's going to ring or a friend that's going to bang on the door and say, "Come for a run", actually, at the end of the day, you have to get off the chair and I always say to people, just walk around the block. Walk down the road and back because once you've got out of the house. So many mental health problems actually are just to do with sort of cycles of thought. Once you're going in this cycle of thought, all you need to do is pivot. You just need to pivot that train of thought which is going around and round, and pick on to another. It can be the tiniest thing - listen to a piece of music, watch some comedy, call a friend, anything, and you can almost feel it when that changes. I feel my eyes change, my whole mood changes because suddenly, I'm not going down that really bleak thing. And so, the exercise thing is really a part of that, just the very fact that you're doing that means that you're no longer going down one part. You're going down another. And you have to be the one to do that unfortunately.

Roger - Just to back you up in that, there's this evidence going back a few decades now for a type of a kind of CBT cognitive behavioural observation. So actually, getting things going, different behaviours, being more active, you know, particularly exercise, that helps us to - is known to be very good for mood. The clinical mantra is on a day-to-day really is even if you don't feel like it, do it anyway because as you were saying, if you do it, 10 minutes or 15 minutes in, you'll get the benefits.

Martin - As been suggested, there can be quite a futile gesture to tell somebody who's really in the depth of depression for example to go out for a jog or to start eating healthily. But you know, I think we can really sort of think about these things like other sort of physical attributes as well. So, if you're overweight, you can't do it for one jog and drop 4 inches off your waistline. But you can prevent becoming overweight by exercising regularly. I think that gets to this combination of using maybe pharmacological treatments to bring somebody out that they have some depression. But then educating people on how stay out of that state, how to avoid going into that state again, and that's where things like getting healthy and exercise I think are very useful.

Liz - That's one of the things which can make depression worse. You know why? Because not what you just said, but the idea of knowing what you know what you have to do. This is why I keep saying to people over and over again, do you know? Actually, nobody ever needs to read it on the magazine or be told all of this stuff. We know this and so, it's the fact that you kind of sit there going, "Look, I know what I have to do, but I feel that I don't have the strength within me to do that" and that brings us back to the question about medication and intervention. If that's the crutch that you need in order to stand up, take that crutch, but you still need to walk and no one's going to make you do that apart from you.

Roger - And just to go back to the point back because it's all about clinical change, psychological change is that actually, it's okay for that to happen in small steps to get in by just going slowly. And there was some research a little while ago that said a new habit takes about 82 days to form. So actually, we can be patient with ourselves as things get going. It's not instant. We can work until that's okay too.

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