This is Amanda who has popped over from Paper, Pens, Ink to do a guest-post for Anita, as part of the All Stars Blog Tour with Philofaxy. Although I largely blog about stationery, I am a physiologist with a particular interest in exercise.
Depression affects many people, with estimates of the number of people affected worldwide cited as over 120 millioni. It is important to realise that ‘depression’ covers a huge spectrum of both physiological and psychological conditions. It can be classed as mild, moderate or severe, according to the presentation of a number of signs and symptomsii.
Much of the research into whether exercise can be used in the treatment of depression has focused on mild to moderate depression and has compared whether exercise is a useful alternative to conventional therapy. Some research has been done on whether exercise is a useful adjunct to conventional therapy. The conclusion of the most recent systematic review of the research found that, “Exercise seems to improve depressive symptoms in people with a diagnosis of depression, but when only methodologically robust trials are included, the effect sizes are only moderate and not statistically significant.”iii
Now, that doesn’t sound too promising a start. However, the way the systematic reviews look at the data is quite critical. One important aspect of clinical trials is to have the participants ‘blind’ as to which group they are in. So for example, in a drug-trial, all participants will be given an identical-looking pill, but only some of them will be taking the drug and the others will be taking a placebo.
When the ‘pill’ is exercise, it is hard to see how the participants can be blind as to which group they are in. In the review, when all the collected data was pooled and examined, a large clinical effect of exercise was indicated. However, when only the data that met certain criteria were analysed, the effect was much less significant.
In the UK, the National Institute of Clinical Excellence (NICE) guideline for depression recommends structured, supervised exercise programmes, three times a week (45 minutes to 1 hour) for 10 to 12 weeks for mild depression2. The National Health Service (NHS) also has a webpage with recommendations regarding exercise for the alleviation of depression.
So, assuming that exercise does have some role in the treatment of mild to moderate depression, how is it doing this?
There are a number of reasons why exercise can alleviate the symptoms of depression. Some of them have a physiological basis and some of them are psychological in basis. To cover them all in depth would constitute a thesis, but I will try to summarise some of the main points.
Physiological changes due to exercise
Many of you will have heard of the ‘endorphin rush’ or ‘adrenaline rush’ or ‘runners’ high’. In all of these cases, the act of exercise changes the release of chemicals in your body. Endorphins are the body’s natural pain-killers and are in the same family of chemicals as morphine. They act at the spinal cord to reduce the transfer of information about pain from the periphery of your body up to your brain (and thereby reduce the perception of pain). They also affect the brain directly. They are useful when you are in pain (obviously) but they are also released when you are exercising, which gives you an exercise/runners’ high. Not all people get a runners’ high though, even during intense exercise.
Another change that occurs in the body is a reduction in the stress hormone cortisol, which has been linked to a reduction in anxiety and depressioniv.
Exercise is thought to help with depression for a number of reasons. It can give you a feeling of control in your life and of goal-achievement. It can act as a distraction, changing your focus on things. It can be sociable if you choose to exercise with others. Exercise, especially done outdoors in the middle of the day can also help you to sleep better.
All of these factors (and more) can help to reduce depression.
What kind of exercise is best?
My answer to that is “whatever you enjoy doing!”. Most of the evidence (both scientific and anecdotal) looks at the affect of aerobic exercise, such as walking, swimming or running. There is also good evidence that yoga helps to reduce anxiety, stress and depression and help you to sleep better toov. Any exercise is better than none, but always exercise within your limits.
Even if you have no clinical diagnosis of depression, exercise can be great for lifting your mood and decreasing your stress and anxiety. It’s also linked to a reduction in many other disease states such as cancer, heart disease, diabetes and stroke. Even if it’s just taking the dog for a walk or managing a stroll around the block, why don’t you go out and get a little exercise today?
Disclaimer: I am not a General Practitioner. I am a physiologist with an interest in exercise. If you are suffering from any of the signs of depression or if you are contemplating undertaking a new exercise regime, please consult your doctor.
i Moussavi S, Chatterji S, Verdes E, Tandon A, Patel V, Ustun B. Depression, chronic diseases, and decrements in health: results from the World Health Surveys. Lancet 2007;370 (9590):808–9.
ivStetler, C and Miller, GE. Depression and Hypothalamic-Pituitary-Adrenal Activation: A Quantitative Summary of Four Decades of Research Psychosom Med 2011 73:114-126
v Field, T. Yoga clinical research review Complementary Therapies in Clinical Practice 2007 17:1-8