When I hear about the current rates of mental illness, I count myself lucky. According to the Canadian Mental Health Association, 1 in 5 people in Canada will personally experience a mental health problem or illness, in any given year. By age 40, about 50% of the population will have or have had a mental illness.
While, thankfully, I don’t have a clinical mental illness, I do have my moments! There are times when the life stresses pile up and it starts to feel overwhelming.
But in the last 10 years or so, I have observed a pattern. When I am in training mode for a marathon, running 4-5 times per week, all is good! Pressures from work or life might be considerable, but it all seems doable. My outlook is positive. Then in my off-season, when running volume sometimes drops down to nil, it can be another story. I start to wake up in the middle of the night with to-do lists in my head or worrying about worst-case scenarios. At times, getting off the couch has seemed like a chore. The difference is so noticeable that I have begun to see running as my medicine.
It appears I’m not the only one. Numerous studies show exercises like running can be an effective treatment for mild to moderate depression and clinical anxiety disorders. But I have questions. What is it ABOUT running that helps my mental health? How much running do I need in my life to feel good? What if I switch to biking? Or would lifting weights do it? Thankfully there are quite a few smart people who have been working on answers to these very questions.
How does running help mental health?
Researchers think there are two main reasons for the mood-boosting effects of exercises like running.
First, there is a well-documented increase in feel-good neurochemicals when you run. Endurance athlete and author, Christopher Bergland, lists at least seven -- from endorphins and endocannabinoids to dopamine and serotonin -- that have been linked to an improvement in mood. Bergland suggests that after 6 or 7 minutes of exercise -- the point at which most people start to sweat -- the body starts amping up these chemicals.
Second, regular running can stimulate the formation of new neurons, particularly in a region of the brain called the hippocampus. The hippocampus is responsible for regulating emotions and is considered the brain’s memory centre. People with depression or anxiety have a significantly smaller hippocampus.
How much running is enough?
We mostly don’t know what the optimal running volume is for most people’s mental health; although we do have some data. Yale researcher SammiChekroud conducted a 3-year observational study of over 1 million people. They found that people who exercised had 40% better mental health than those who did not. As well, the exercise sweet-spot for participants was 30-60 minutes, three to five times per week - very manageable for most people! Mental health benefits were reduced when exercise frequency dropped below that amount...and more was not better.
In fact, the study findings showed that exercising every day was associated with worse mental health. (Uh oh!) There are at least two possible reasons for this. One is that exercising every day increases your stress load and that extra burden affects your anxiety or depression. Another possibility is that people with certain mental health problems are much more likely to exercise to extremes (maybe those with obsessive-compulsive disorder, or with significant body image issues). Makes sense - but we can’t know for sure. With observational studies like this one, we can only notice associations, not draw conclusions about causation.
What about exercise intensity?
Because I like to get specific, I was curious about the impact of intensity of exercise on your mood. What if I’m running too slow to maximize the mood-enhancing benefits? Or too fast?
Well, I found a study for that too! There is a 2017 mental health study comparing low, moderate and high levels of physical activity. The study team measured endocannabinoid signaling (think feel-good brain chemicals). They observed that moderate activity levels have a bigger response than very low or very high intensity exercise. Running at a moderate intensity means you are putting the effort in but can carry on a conversation. This is doable for lots of people. With a bit of training, most of us can keep this up for a 30-60 minute run.
What about other forms of exercise?
The majority of research on mental health and exercise has been done on running. But the Chekroud study observed all types of exercise. The study team found that any physical activity was associated with better mental health. But team sports, cycling, aerobics and running had the biggest impact.
But I think it’s important to realize whatever exercise you choose has to be enjoyable -- we are talking about mood here. Pick something you like doing and stick with it. Even an activity like yoga has been shown to reduce stress, and relieve anxiety, depression, and insomnia.
There is a University of Michigan study about exercise and mental health that had puzzling results. The study team gave questionnaires about depressive symptoms and exercise to 1100 college students at Beijing University. It found an association between exercise and mental health protection - but only for men. Women didn’t have the same benefit.
These results contradict the findings in the much larger Chekroud study (with 1.2 million participants). In that study, the association between exercise and mental health was seen for both men and women.
Because of the difference in results between these two studies, I think we need to pay attention to current studies and pursue further studies. If you are a woman and don’t get mental health benefits from exercise - I’d like to hear from you!
Running (likely) makes us feel better. And the studies can provide some guidance around frequency, volume, and intensity. Does it mean you should go off your antidepressant medications and pick up your running shoes after reading this blog post? No, please don’t. But depending on your symptoms and your life circumstances, it may be worth having a conversation with your doctor about it.
Dr. Michael Torreiter, ND, CFMP
Dr. Michael Torreiter is a Doctor of Naturopathic Medicine. About half of Dr. Torreiter's practice is focused on Precision Nutrition — a comprehensive weight management and lifestyle program that helps people lose weight, gain weight or just improve their diet. In addition to prediabetes and diabetes, he treats a variety of conditions including digestive concerns, stress and anxiety, musculoskeletal pain, hormonal imbalance and men’s health.
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