The physical health benefits of exercise are well researched and understood. But what do we really know about exercise and it’s effect on our mental health?
We’re always being told to do more exercise because of the masses of evidence it wards off a host of nasty illnesses.
But if you’re someone who uses a good walk, run or gym workout to shake off stress or lift a low mood, there’s some science on your side too.
While there’s less known about the effect of exercise on your mind compared to your body, what is known suggests it’s likely to beneficial and generally unlikely to cause harm, says mental health expert Professor Tony Jorm.
“It’s one of those things that even though the evidence isn’t rock solid, there are other potential benefits and the risk of harm is so minimal, it’s a good thing to do,” says Jorm, one the authors of a recent position statement on exercise and mental health commissioned by Exercise and Sports Science Australia.
“Exercise is about as low risk as you can get and the side effects are about as minimal as you can get.”
And the benefits for physical health are so extensive, that even if it doesn’t help your mood or mental state, “it will potentially help a whole lot of other things”.
Get moving, get happy?
Whether it’s pounding the pavement on a daily run, clocking up laps in the pool or salsa dancing, those who make a habit of exercise often say one thing that helps them stick at it is that it simply makes them feel good.
Dr Nicola Burton, senior research fellow in the University of Queensland’s school of human movement studies, says when it comes to exercise “we’re not only talking about preventing poor mental health or treating it, but promoting good mental health. Even if you don’t have depression or anxiety or a serious mental illness that you want help managing, you can enhance your wellbeing and vitality.”
This is because exercise can boost mood, concentration, alertness, and even your propensity to look on the bright side, she says.
“We’ve just done a study showing people who engage in regular exercise experience higher levels of optimism.”
Indeed not only does research show regular exercisers have better mental health and emotional wellbeing and lower rates of mental illness, but studies that track people over time show taking up physical exercise seems to reduce the risk of developing mental disorders.
For instance, a 2011 Dutch study of more than 7000 adults found that doing exercise reduced the risk of developing a mood or anxiety disorder over the following three years, even when controlling for socioeconomic factors and physical illnesses.
But the relationship between exercise and mental health is “complex and bidirectional” – in that inactivity can be both a cause and consequence of mental illness, says Jorm, from the Centre for Mental Health at the University of Melbourne.
“When people get a problem like depression or severe mental illness, it affects their motivation and enjoyment of life, and that can drive physical activity down. But there’s also probably a reciprocal effect, in that when they exercise less, that seems to make [their mental health] matters worse.”
The exercise prescription
Exactly how exercise might boost mood isn’t well understood. Some possibilities are that it:
- helps you sleep better
- gives you an improved sense of control, coping ability and self esteem
- provides distraction from negative thoughts and a chance to have new experiences
- offers an opportunity to socialise and get social support if done with others
- changes the levels of chemicals in the brain, such as serotonin, stress hormones and endorphins (substances that can block pain and may also enhance feelings of wellbeing).
There’s also no clear evidence on which type of exercise works best, or how much is needed to bring about different effects. While intense exercise may have greater benefits, it’s better to start at a low level and gradually build up than aim too high and risk being turned off, says Jorm. Thirty minutes brisk walking a few times a week is a good general starting point, he suggests. You don’t have to do the 30 minutes all in one go, but it’s best if you do it in blocks no shorter than 10 minutes.
For many people with mild depression or anxiety, that “may be sufficient to produce some improvement in their mood; to stop it worsening so they don’t have to go off and get other types of treatment,” he says. “I think it should be universally used.
“I think there also could be value in increasing the level of activity in the population as a preventive measure.”
Jorm himself cycles daily, including to and from work, and rarely uses a car or public transport. He describes himself as “one of the fortunate people who has a very stable mood” but says the exercise nonetheless benefits him mentally.
“It gives me a positive feeling. I miss it if I don’t do it.”
On longer trips, he finds he is flooded with creative thoughts and afterwards notices a definite improvement in his sleep.
“To me it’s like the sleep of childhood, the sort of deeper sleep that is very satisfying.”
Exercise to treat mental illness
What does it help?
Apart from depression, exercise is not considered an established treatment for mental disorders. Nonetheless, the Royal Australian and New Zealand College of Psychiatrists recommends that exercise may complement other treatments for mental illnesses and be used to help recovery, prevent recurrences, and manage the side effects of some medications.
The evidence from randomised controlled trials suggests exercise has a moderate to large effect for people with depression. It is also moderately effective for anxiety.
However, people with severe depression may find it very hard to exercise and even when they can, it needs to be seen as an adjunct to treatment, rather than a treatment on its own, says Dr Caryl Barnes.
For people with psychotic disorders such as bipolar disorder and schizophrenia, it may help improve functioning and physical health.
Exercise has been shown to improve schizophrenia symptoms such as blunted emotions, loss of drive and thinking difficulties. But it is less helpful for delusions and hallucinations.
It’s worth noting though, that for some mental health conditions, exercise is actually part of the problem. “Excessive exercise for someone who’s got an anorexic illness can actually be quite harmful,” says Barnes. And increased exercise can sometimes be an early warning sign of a manic phase for those with bipolar disorder. In those cases, continuing to exercise at a high level may serve to “rev” a person up, and exacerbate the mania, which would not be helpful, she says.
How much and what sort of exercise?
There is limited research to guide how much and what sort of exercise to do. But both aerobic exercise and resistance exercise may be effective. (Aerobic exercise gets your major muscles moving and your heart and breathing rate up but can be done for a sustained period eg walking, swimming, cycling. Resistance exercise is exercise that strengthens muscles by making them work against a force such as weights or your own body weight eg weight lifting, lunges, squats.)
Three exercise sessions per week, each lasting at least 30 minutes at moderate to vigorous intensity are recommended for a minimum of 8 weeks. (Moderate intensity exercise requires some effort, but still allows you to speak easily while vigorous intensity exercise takes more effort and makes you breathe harder and faster so it is difficult to speak.)
Higher doses of exercise may be more effective at improving mental illness but people may be less likely to stick to them.
Physical benefits for those with mental illnesses
The physical benefits of exercise may be especially important to those with severe mental illnesses such as schizophrenia, who die on average 16 to 20 years earlier than the general population – largely because of physical health risk factors stemming from poor access to medical care, poor diet, little exercise and weight gain related to medication use.
People with depression may also benefit physically from exercise as they are known to be at higher risk of heart disease, although no-one’s quite sure why.
“[If you’re depressed] that’s another reason to try and build exercise into your life long term – for its protective effect [against heart disease],” says Jorm.
This article first appeared on ‘ABC‘ on 26 August 2014.