3 Why does exercise improve mental health?

Physical exercise’s impact on mental health ought to be able to work for everybody, basically because of the potential underlying mechanisms that are thought to explain why physical activity would impact. And those mechanisms range from very specific impacts of physical activity on neuro-transmitters in the brain through to the effect that just going for some physical activity exercise has as a time out, as a distraction from your day-to-day worries. Each of those theories – whether we're talking about a neuro-transmitter explanation or an endorphin explanation, or we're talking about the mastery, the confidence that you may get from exercise – all have some strengths, and they all have some weaknesses.

We can talk about bio-physical processes or psychosocial processes....It's useful to look at psycho-social processes. We call it the 'three C's' in terms of how people feel in terms of their competence, how much control they have over their behaviour and how it impacts on their health and, also, how much companionship and relatedness that they have with other people. Those three things seem to be quite important for mental health. If we feel competent about what we do, we tend to feel better about ourselves and have better mental health. If we feel in control, we can control what we do, we have choice, autonomy over what we do, and we feel that it actually makes a difference to how we are. And if we feel that other people are interested and we can relate to other people, then that also helps us feel better about ourselves, and our mental health tends to be better.

Some people will not appreciate that and will not accept that they're physically becoming more in control in their lives, or that they're physically becoming fitter, potentially because of their other mental health problems. And so for them, it might not work from a mastery perspective as successfully. But that doesn't mean to say that the other neuro-psychological changes aren't occurring.

People have been interested in the link between physical activity and mental health through bio-physical processes. Bio-physical processes could include several things, one that there is a temperature change, as you exercise you become warmer, which has been associated with feeling better. So those might be some temporary changes. But in terms of longer term changes through a prolonged period of activity, what might some of the changes be? One of them might be reductions in muscle tension, so you feel less aroused and less stressed, if you like, so there are physical changes in muscle relaxation.

The neuro-transmitter explanations and the endorphin explanations and the thermagenic, which is that muscle-warming, muscle relaxation, they have problems in that as soon as I start to exercise there's more oxygen circulating, that triggers endorphins and neuro-transmitters and relaxes muscles, so all of the systems are being activated and, therefore, to be able to say it's this one that's having the effect is unlikely to occur. And so we now talk much more about having a synergy, having a combination of those mechanisms to actually explain why it works.

Other ones might include changes in the way the brain functions. Increasingly, people are interested in development of Alzheimer's and dementia in older people, and whether physical activity influences that through some kind of regeneration of brain tissue associated with cognitive functioning. So there is some evidence that exercise may influence how we process information, which is related to changes in the brain. Other people often talk about reductions in depression related to endorphins. Endorphins are quite complicated molecules, it may not be quite as simple as simply increasing endorphins, there might be other things such as dopamine, which is more important and linked to mood states and reduction in depression. So several ways, several bio-physical ways in which exercise might improve mental health.