In this recent MedCram video, Dr. Seheult, discusses how even minimal to light exercise may have a reduction in the incidence of depression.
How much exercise do I really need?
People often assume that when they are told by their doctor or a healthcare professional that they need to exercise more, they will need to spend long hours at the gym or expend lots of energy on strenuous activities to achieve their exercise requirements. What studies are showing is that the amount of exercise needed to get benefit is much less than people think. Per the recommended physical activity guidelines for Americans, it states that each week adults need at least 150 minutes of moderate-intensity physical activity and 2 days of muscle strengthening activity. This ends up being appropriately 9 MET hours/week.
What is a MET?
For clarification, a MET is considered to be the equivalent to the consumption of 3.5 ml of oxygen per kilogram per minute. Examples of light exercise would be 1.5 marginal METs above what you are doing at rest, 3.5 marginal METs for moderate to vigorous activity and 7 marginal METs for vigorous physical activity. This article can provide further examples of different activities for METs.
What does the research show?
Today many people are busy and they may be already depressed. As a result, they may have low motivation to exercise. Is there evidence that doing even light exercise has an effect on the risk of depression? This study from JAMA psychiatry in 2022 was a meta analysis that looked at studies with outcomes more than 3 years and more than 3000 subjects. The outcome they were looking at was depression. When all of the studies were looked at, they found that overall if someone did just 4.4 MET hours per week they had an 18% reduction in depression risk association, 17% reduction in major depression and a 20% reduction in elevated depressive symptoms. If they achieved 8.8 MET hours per week, they found the numbers went up to a 25% reduction in depression risk association, 25% reduction in major depression and a 22% reduction in elevated depressive symptoms. However, if the MET hours per week went up to 17.5 there was still improvement but not as good as the lower MET hours i.e. 23% reduction in depression risk association, 26% reduction in major depression and a 30% reduction in elevated depressive symptoms. The improvement from 4.4 to 8.8 MET hours was greater than going from 8.8 to 17.5 MET hours. There appears to be a larger benefit earlier within the initial MET hours done than at higher levels. A graph Dr. Seheult illustrates on the video shows that the majority of the benefit on depressive symptoms occurs with activity under 5 MET hours/week.
Exercise effects on mood
For an individual who is depressed, he or she needs to battle to avoid being sedentary. Just moving around a small amount will have a large impact on mood. The conclusions from the study were that there was an association between physical activity and incident depression. The study suggested that substantial mental health benefits can be achieved at physical activity levels even below the public health recommendations. Assuming causality, 1 in 9 cases of depression might have been prevented if everybody in the population was active at the level of current health recommendations.
How does exercise affect depression in the youth?
It’s extremely important if you are depressed to not be sedentary. Even simple walking can improve your mood. This study was a prospective cohort study that involved 3352 subjects and looked at activity using measured depression scores at 12, 14, 16 and 18 years of age. They noticed that the amount of moderate to vigorous activity did not change throughout those years, but as the youth aged, the amount of sedentary behavior went up and the amount of light activity went down. The study found that the amount of activity was statistically significantly associated with a reduction in depression whereas sedentary behavior was statistically significantly associated with an increase in depressive symptoms. This was seen in both the adjusted and unadjusted model. Light activity across all age groups was protective against depression. The authors found that overall as sedentary behavior increased and light activity decreased throughout adolescence and it was consistently associated with depressive symptoms at 18 years of age.
From Dr. Seheult’s perspective there is additional benefits to get the light activity completed earlier in the day where you can get exposure to sunlight and infrared radiation for additional benefits. This video from MedCram discusses this in terms of stress, anxiety and immunity. Medcram.com has a free course on optimal health and immunity for further information.
LINKS / REFERENCES:
How much physical activity do adults need? (CDC) | https://www.cdc.gov/physicalactivity/…
Association Between Physical Activity and Risk of Depression (JAMA) | https://jamanetwork.com/journals/jama…
Depressive symptoms and objectively measured physical activity and sedentary behaviour throughout adolescence: a prospective cohort study (The Lancet) | https://www.thelancet.com/journals/la…
Stress and COVID 19: Improving The Immune System, Anxiety, and Depression (MedCram) | • Stress and COVID …