*Only for reading and reference by medical professionals
Everyone knows that exercise has many benefits, but it is difficult to insist on doing it. Especially under the dual pressure of life and work, do you occasionally feel that you are going to be depressed, and at the same time, it becomes more difficult to maintain exercise? In fact, you are not the only one who feels this way, most people have similar troubles like you. But the good news is that some scientists have a solution.
Not long ago, James Woodcock’s team at the Clinical School of Medicine at the University of Cambridge published a research result in JAMA Psychiatry. They found for the first time that there is a dose-effect relationship between physical activity and depression . Specifically, compared with no physical activity, only 8.8 mMET hours of cumulative physical activity per week (approximately equivalent to a weekly brisk walk 2 and a half hours), is associated with a 25% reduction in the risk of depression [1].
Screenshot of the paper's homepage
While social modernization has extended human lifespan, a series of lifestyle issues are having an increasingly obvious negative impact on our mental health under the influence of technology. Depression has become a mental disease that seriously endangers human health, and effective preventive measures are urgently needed.
Although there is currently a lot of research evidence that exercise can prevent the occurrence of depression [2], it is still unclear how much activity is required to effectively prevent depression. Moreover, these studies involve a variety of assessment methods, and it is a challenge to combine data analysis to clarify the dose-response relationship between physical activity and health benefits.
Faced with such a challenge, the James Woodcock research team tried to use a new idea, to uniformly convert various physical activities of different types, different intensity, and different frequencies into net metabolic equivalents (mMET) for analysis . mMET is the ratio of the energy consumed by the body during activity minus the energy consumed at rest to the energy consumed at rest. Simply put, the higher the value of mMET, the greater the intensity of physical activity..
In this study, the research team divided physical activity into 3 different intensity levels and assigned different mMET values, namely mild = 1.5 mMET, moderate = 3.5 mMET, vigorous = 7 mMET, and then used the mMET value Multiply the weekly physical activity time (hours/week) of the corresponding intensity, and the sum of the three physical activity levels is the total weekly physical activity level. Taking a participant's physical activity level = 8.8 mMET hours/week as an example, this is equivalent to approximately 2 and a half hours of moderate-intensity physical activity (such as brisk walking) per week.
Next, let’s talk specifically about how James Woodcock’s team conducted a meta-analysis of and . The
research team collected 19,173 documents by searching PubMed, SCOPUS, Web of Science, PsycINFO and other databases. After screening and exclusion, 15 prospective cohort studies with a follow-up time of 3 years or more were finally included, involving a total of 19,173 documents. More than 190,000 adult participants, approximately 64% of whom are female.
In the studies included in the analysis, participants self-reported physical activity via questionnaires, and depression was diagnosed and assessed by a physician. It is worth mentioning that physical activity includes not only various sports, but also doing housework, planting flowers and vegetables, etc. are also included in the analysis. Subsequently, the research team used the calculation method mentioned above to calculate the total physical activity level of the participants per week and conducted a correlation analysis with the risk of depression.
The results found that most participants (78%) had physical activity levels below 17.5 mMET hours/week, and almost all participants (95%) had physical activity levels below 35 mMET hours/week. Furthermore, participants with increased depressive symptoms were less physically active during the cohort study follow-up period.
Even more importantly, the research team found that low levels of physical activity can prevent depression!
James Woodcock's team conducted a dose-effect analysis on the results of at least 4 cohort studies and found that there is a dose-effect relationship between the amount of physical activity and the risk of depression. Compared with no physical activity at all, physical activity reaching 4.4 mMET hours per week was associated with an 18% lower risk of depression (95% CI, 13%-23%), while physical activity reaching 8.8 mMET hours per week was associated with an 18% lower risk of depression (95% CI, 13%-23%). , the risk of depression can be reduced by 25% (95% CI, 18%-32%) , but more physical activity will have almost no additional benefits.
Dose-response relationship between physical activity levels and the development of depression
For participants who already suffered from depression, physical activity was also effective. Compared with no physical activity at all, physical activity reaching 4.4 and 8.8 mMET hours/week is associated with a 20% (95% CI, 12%-27%) and 27% (95% CI, 16%) lower risk of worsening depressive symptoms. -36%) related. Therefore, whether you are a healthy person or a patient with depression, sitting for a while and moving a little can bring you a good mood.
Relative risks and potential effects of depression, major depression, and exacerbation of depressive symptoms at three levels of physical activity
Why does physical activity have such a miraculous effect? The research team also gave their explanation that when we move our bodies, related neuroendocrine systems are activated, such as the endocannabinoid system. Activation of this system not only blocks pain, but also produces a feeling of happiness [3]. In addition, some research shows that if we can maintain a certain amount of physical activity for a long time, the neural structure of our brain may change, making us less susceptible to depression [4]. At the same time, more physical activity may increase our social range and have significant improvements in self-perception and body image [4].
At the end of this study, the author also mentioned that the studies included in the analysis collected data on physical activity through self-reporting by participants. The accuracy of these data may be affected by memory bias and social desirability bias. In the future, we hope to use machines and equipment to measure physical activity and conduct longer follow-up to obtain more objective and accurate data.
Overall, this study is the first to clarify the dose-effect relationship between physical activity and the risk of depression, and provides quantifiable and implementable guidance and recommendations for the prevention of depression. The author of
specifically pointed out at the end of the article that even if the amount of activity is lower than the amount of activity recommended by the World Health Organization (150-300 minutes of moderate-intensity physical activity per week for adults aged 18-64, or 75-150 minutes of vigorous-intensity physical activity per week), Can reduce the risk of depression! Moreover, if everyone can consciously increase exercise and achieve the amount of exercise recommended by the World Health Organization, then 1 in 9 patients with depression can be prevented. Look at it this way, preventing depression does not actually require deliberate exercise. It can be easily achieved as long as you appropriately increase physical activity in your life, such as walking on the way home, taking less elevators and taking more stairs, and changing takeout to dine-in.
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Reference:
[1]. Pearce M, Garcia L, Abbas A, et al. Association Between Physical Activity and Risk of Depression: A Systematic Review and Meta-analysis[J]. JAMA Psychiatry, 2022, 79(6): 550-559.
[2]. Schuch FB, Vancampfort D, Firth J, et al. Physical activity and incident depression: a meta-analysis of prospective cohort studies[J]. Am J Psychiatry. 2018, 175(7): 631-648.
[3]. A Dietrich, W F McDaniel. Endocannabinoids and exercise[J]. Br J Sports Med. 2004, 38(5): 536-41.
[4]. Kandola A, Ashdown-Franks G, Hendrikse J, et al. Physical activity and depression: Towards understanding the antidepressant mechanisms of physical activity[J]. Neurosci Biobehav Rev. 2019, 107: 525-539.
[5]. Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behavior[J]. Br J Sports Med. 2020, 54(24): 1451-1462.
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