We all know that doing sport or exercise makes us feel better. It can make a stressful day at work seem less overwhelming, help you cope with difficult life events or make you feel better about yourself. In fact, exercise is recommended as a way to cope with mental health problems such as depression and anxiety.
But how much do we really understand about the mechanisms behind this link? There are many different ways that scientists and psychologists suggest exercise may help our mental. A few of them are explained here but it is likely that in reality a combination of these factors work together to create this effect.
The monoamine hypothesis
Before we get started on understanding this theory, lets just get clear on what monoamine neurotransmitters actually are. Monoamines are a type of chemical structure containing a particular molecule (an amine, hence the name) and neurotransmitters are chemicals which can carry messages across synapses (the gaps between cells, in this case neurons). Therefore monoamine neurotransmitters are neurotransmitters which have an amine molecule as part of their structure. The ones we are particularly interested in here are the neurotransmitters serotonin, noradrenaline and dopamine.
In people with mental illnesses, such as depression and anxiety, levels of these neurotransmitters can become unbalanced. This is problematic as each of these has an important role to play in keeping us happy and healthy.
Serotonin is important for regulating physiological functions such as sleep, something which can be difficult in people with mental illnesses. This can be shown by the fact that people with depression tend to have decreased serotonin production.
Noradrenaline helps us to respond to stress appropriately. This is obviously ideal when faced with an actual threat like a car pulling out suddenly in front of us but isn’t something that is helpful all of the time. This is partly why people struggling with anxiety can feel constantly worried as their bodies have too much noradrenaline and as a result feel like they are constantly dealing with a threat. On the other hand, people with depression can have low levels of noradrenaline.
Dopamine regulates our ability to feel pleasure and have motivation. The difficulty in experiencing pleasure and having motivation in people with depression can be explained by the low dopamine in the brains of these individuals.
It is therefore apparent that these little chemicals are very important for our wellbeing and imbalances in them can cause serious problems. The monoamine hypothesis suggests that exercise is able to correct these imbalances in a similar way to how medications such as SSRIs (Selective Serotonin Reuptake Inhibitors) work. It is thought that exercise can prevent the reuptake by neurons of these neurotransmitters in the brain. This means that the availability of them is increased, leading to an increase in our mood.
The thermogenic hypothesis
This theory isn’t very well supported by research but may still be relevant as it is likely that a number of different factors contribute to exercise making us feel good.
It is suggested that as exercise raises core body temperature (I’m sure you are already aware of this), the temperature of some brain regions increases. It is thought that this leads to reduced muscle tension which helps to enhance feelings of relaxation, which can have a positive effect on anxiety.
The role of mitochondria
Mitochondria are found inside cells and produce ATP (adenosine triphosphate) which is a small but very important chemical which provides us with energy.
The reason this is relevant to understanding how exercise can effect our mental health is that mitochondria are needed for neuroplasticity (the ability to create new connections, or pathways in the brain). This is important as neuroplasticity helps us to respond and adapt to problems, such as chronic stress.
The trouble is that it is thought that people with some mental illnesses such as bipolar, depression, anxiety and OCD have mitochondrial dysfunction and so cannot carry out neuroplasticity effectively. This means that they cannot respond to stress appropriately. Mitochondrial dysfunction can also cause fatigue, a feature of many mental illnesses. This makes sense as mitochondria are responsible for producing energy.
The good news is that exercise can increase mitochondrial biogenesis (the production of new mitochondria). These shiny new mitochondria can then help increase neuroplasticity levels, enabling us to respond and adapt to problems more effectively, which should help our mental health.
The role of the HPA axis
The HPA axis is an abbreviation of the Hypothalamic Pituitary Adrenal axis. This is a name for the interactions that take place between the hypothalamus and pituitary glands in the brain and the adrenal glands, which are above our kidneys. The HPA axis is responsible for adapting to stressors we may encounter.
As with noradrenaline this is obviously helpful when dealing with an immediate, potentially life threatening problem. The problem arises when the HPA axis is hyperactive, as is the case for people struggling with anxiety and depression.
Basically what this means that these people are always producing too much cortisol. This is a hormone which helps us deal with stress which is helpful but in too large quantities can cause problems. These range from mental health problems to physical health problems such as weight gain and heart disease.
Conveniently, exercise is able to regulate the response of the HPA axis. This leads to a lower, more healthy level of cortisol being produced which can lead to improvements in mental health.
As you have probably gathered by now chronic stress isn’t good for us. Another one of the problems it can lead to is increased levels of inflammation. Some mental illnesses such as schizophrenia, OCD and depression have been linked to increased levels of inflammation.
Exercise is able to reduce this inflammation through a variety of different mechanisms, which can lead to improvements in these mental health conditions.
There are also a number of different psychological theories for how exercise may help our mental health.
One of these is the distraction hypothesis. This is basically what it says on the tin. It is the idea that the simple act of exercising and therefore having some time out from all the other worries, stresses and negative thoughts in your life is helpful.
Another suggestion is that exercise increases our self-efficacy. This is a concept that is similar to self-confidence but is instead our beliefs about how good we are at a specific task. The specificity of these beliefs is important as an individual can have high self-efficacy in one area, such as their ability to run a 10k but low levels of self-efficacy in other areas, such as their ability to run a marathon.
Successfully completing an exercise session should hopefully increase your self-efficacy of your ability to complete that type of exercise. Over time with repeated successful exercise sessions your self-efficacy in that area will increase. This will lead to increased levels of adherence to that activity, giving you more opportunity to improve and increase your self-efficacy, leading to increased adherence and so on. This positive upward spiral will make you feel better about yourself as you master a new skill and keep improving at it. It is thought that this can also explain how exercise makes us feel good.
It is probably clear by now that there are many different suggestions for how exercise can have a positive impact on mental health. It is likely that more that one of these mechanisms plays a part. One thing is clear though – while scientists and psychologists argue over which is most important there definitely a link. This means that doing even small amounts exercise will help your mental health. For useful website and resources to get started with exercise to experience these benefits, click here.
Happy exercising 🙂