Recommendations of physical exercise and its relation to mental health

Andrés Fontalba

The Lalonde report marked a milestone in the 1970s, highlighting the importance of lifestyles in health, over the characteristics of the health system or the biology of the person and proposing a change of the model based on the “cure” for one that boosted "health promotion". Among the lifestyles, most related to health is physical exercise. Plato already warned us: "The lack of activity destroys the good condition of every human being, while movement and physical exercise preserve it."

Physical exercise is associated with several health benefits, including reducing overall mortality and improving musculoskeletal health, stress regulation, reducing the risk of cardiovascular disease, obesity, cerebral-vascular disease and cancer. However, so far, research on the effect of exercise on mental health has provided conflicting results. Several clinical and observational trials consider exercise an effective treatment for moderate depression, either alone or in combination with other therapeutic strategies. But these results are not very strong and are under discussion. Some observational studies show positive evidence in favour of physical exercise and mental health in adults, but do not reflect this association in adolescents. Similarly, there is no consensus on a possible linear association, which would be to proportionally relate more exercise to better mental health. This controversy may appear reflected in clinical practice. Health professionals often recommend physical exercise, but this advice does not usually contemplate the type of activity that would be most beneficial, neither its intensity nor frequency, aspects that are essential in adapting the physical activity to the circumstances of the person depending on the therapeutic and preventive approach.

To solve this problem in mental health, a study has recently been published in The Lancet Psychiatry in which the data of 1,237,194 people from a survey of surveillance centres and prevention of disease risk factors between 2011 and 2015. Participants were asked about the previous 30 days, to determine how many had had problems related to mental health such as depression, stress or emotional disorders, and those who exercised were compared with those who did not. One of the interesting points of this analysis was that the type of physical exercise was explored, as well as its intensity and frequency. Among the main findings, it is worth highlighting that people who exercised had 43.2% fewer days with mental health problems in the last month than those who did not practice it. All types of exercise were associated with fewer days of mental health problems (between 11.8% and 22.3%), compared to those who did not exercise. Within the different types, the strongest associations were shown in team sports (22.3% less), cycling (21.6% less) and aerobic and gymnastic activities (20.1% less), as well as more association at a duration of 45 minutes and a frequency of three to five times per week.

Another very important facet of the study was that the effect of physical exercise was even greater in people with a diagnosed history of depression compared to those who had not. And the effect of exercise on mental health was greater than other demographic and socio-economic factors such as educational level, income level or body mass index. Until now it was argued in multiple forums that more exercise was always better. In this study, small reductions of days with poor mental health were observed in people who exercised more than 90 minutes a day, but exercising for more than three hours a day was associated with worse mental health than doing nothing, which calls into question the linear association. The authors related it to the theory that people who perform extreme amounts of exercise may have obsessive characteristics that could place them at a higher risk of poor mental health.

While the results suggest that exercise can improve mental health, this relationship is complex and can go both ways, so all results should be analysed with caution. For example, a sedentary lifestyle can be a symptom and a contributing factor to poor mental health, and being active could be a sign of recovery or a contributing factor to it, hence the association and not causality is highlighted. Since today depression is the main global cause of disability there is a pressing need to identify modifiable factors that influence the mental health burden and which, in turn, can be targets of health campaigns for the population.

From the results of this study, we can conclude that physical exercise is associated with better mental health, but in terms of its recommendation as a preventive or therapeutic measure, we must be more precise than usual, indicating the type of activity, frequency and intensity of the same. You have to build up a sweat but without overdoing it, to reduce stress, depression and emotional problems.