Newsletter #187 - Exercise & Mental Health 💪🏽
Good morning humanOS friends! This week, we took a look at some research on the benefits of exercise on mental health.
This is particularly relevant right now, since analyses of data from smartphone accelerometers has revealed that physical activity started to decline worldwide during the pandemic, and it’s likely that those effects continue to reverberate today. There is reason to believe that this has had an impact on mental health, especially for vulnerable individuals - lots of time spent sitting was shown to be a behavioral risk factor for blunted improvement in depressive symptoms in 2020. On the other side of the coin, people who exercise seem to fare better. For instance, people who reported engaging in ≥30 minutes of moderate activity per day were ~30% less likely to present symptoms of depression/anxiety, and those reporting ≥15 minutes of vigorous activity were ~40% less likely to present such symptoms.
The underlying mechanisms are not entirely clear; it is likely multifactorial. It has been suggested that physical exercise may increase anti-inflammatory factors in the brain (inflammation is linked to depression, as we’ve discussed before), increase availability of tryptophan to the brain, and boost the production of growth factors like BDNF. In any case, regardless of the actual reasons, the benefits of exercise for mental health are pretty hard to deny. To learn more, scroll down 👇
This Week's Research Highlights
🚴♀️ Various forms of exercise are associated with reduced burden of poor mental health.
In a cross-sectional study, researchers analyzed survey data from 1,237,194 American adults (yes, very big study!). Specifically, they compared the number of days of bad self-reported mental health between individuals who exercised and those who did not. In order to try to control for other potential confounding variables, they matched the two groups (exercise vs. non-exercise) in terms of age, race, gender, BMI, income, and other factors. They found that individuals who exercised had ~43% (around one and a half) fewer days of poor mental health, compared to those who did not exercise but who were otherwise similar in physical and sociodemographic characteristics. All exercise types were beneficial, but the strongest associations were found for team sports (22.3% lower), cycling (21.6% lower), and aerobic and gym activities (20.1% lower), as well as durations of 45 minutes and frequencies of 3-5 times per week.
⚡️ A physically active lifestyle is linked to lower risk of developing anxiety.
Researchers in Sweden looked at data from all Swedes who participated in the world's largest long-distance (30–90 km), cross-country ski race (Vasaloppet) between 1989 and 2010 (n = 197,685), and compared them to matched individuals from the general population (n = 197,684). Vasaloppet skiers are a convenient group to use for examining the effects of exercise since they are decidedly more active than the average person. They followed the subjects for up to 21 years, and referred to a national patient registry to retrieve any psychiatric diagnoses. The researchers found that skiers had a nearly 60% lower risk of developing anxiety over the followup period, compared to non-skiing counterparts.
🧠 Physical activity protects against depressive episodes, even in individuals with the highest genetic vulnerability to major depression.
Researchers looked at genomic data from 7,968 individuals and calculated their genetic risk for developing depression, based on genomic variants that have been shown to be associated with depression. When they looked at electronic health records for the subjects, they found that people with a higher polygenic risk score for depression were indeed more likely to have been diagnosed with a depressive disorder. When they compared lifestyle-related survey responses, they found that physical activity showed a protective effect against depression, of a similar magnitude to the impact of genetic risk, even after adjusting for BMI, education, employment, and prior depression. Importantly, higher levels of physical activity were associated with lower odds of depression across all levels of genetic risk, even in those with the highest risk scores for depression.
💪 Higher fitness and muscle strength is also linked to lower risk of depression and anxiety.
Researchers in the UK looked at data from 152,978 UK Biobank participants who had been tested on cardiorespiratory fitness and grip strength (a commonly used measure of muscular strength), and who had taken questionnaires to estimate incidence of common psychological disorders. Across a seven-year followup period, the researchers found a dose-response relationship between both measures of fitness and mental health. Participants who were classified as having low combined cardiorespiratory fitness and muscle strength were found to have 98% higher odds of experiencing depression and 60% higher odds of experiencing anxiety, compared to subjects who rated high for both forms of fitness.
Random Trivia & Weird News
🐈⬛ A Siamese cat co-authored a scientific paper.
In 1975, physicist Jack Hetherington of Michigan State was preparing to submit a paper to Physical Review Letters when he realized he had made a critical grammatical error - he was listed as the sole author, but had used the plural “we” and “our” throughout the article. Knowing that the journal would reject it on this basis, but also not wanting to retype the whole thing, he added his cat, dubbed F.D.C. Willard, as the co-author, and it was subsequently published.
The American Physical Society has generously made all papers authored by cats open-access, so you can easily check out that paper if you wish.
Podcasts We Loved This Week
- Allan Sniderman: Cardiovascular disease and why we should change the way we assess risk. Via The Peter Attia Drive.
- Bruce Neal: Can salt substitutes reduce cardiac events and death? Via Sigma Nutrition Radio.
Products We Are Enjoying
Fitbit
If you are trying to increase levels of physical activity throughout the day, some kind of movement tracker is basically a must. Can’t manage what you don’t measure, right? Pedometers have actually been around since the 1700s, but modern digital activity trackers obviously offer a lot of other benefits, such as heart rate monitoring, as well as a much more appealing user interface. Fitbit has been one of the most popular for quite a while, and it is one that all of us continue to use here (and of course, you can easily sync your Fitbit data to your humanOS Dashboard for a more complete view of your activity patterns over the course of time).
humanOS Catalog Feature of the Week
Thanks for reading and we will see y'all next week!