Sport and physical exercise in sustainable mental health care of common mental disorders: Lessons from the COVID-19 pandemic

Abstract

The large-scale disruptions to physical activity during the coronavirus pandemic have been found to be a leading predictor of common mental disorders. In addition, regular physical exercise has been found to alleviate anxiety, sadness and depression during the pandemic. These findings, together with numerous studies published before the pandemic on the effects of physical activity on mental health, should be considered in the provision of mental health care following the pandemic. Cross-sectional research has revealed that all types of exercise and sport are associated with a reduced mental health burden. Therefore, the effectiveness of exercise and sport participation in sustainable mental health care as well as the causal relationship between exercise, psychosocial health and common mental disorders merit further investigation. Physical activity and sport, with their global accessibility, significant and clinically meaningful efficacy as well as virtual absence of adverse effects, offer a promising option for the promotion of mental health, including the prevention and treatment of common mental disorders. Physical exercise and sport are likely to become valuable public mental health resources in the future.

Abbreviation

COVID-19

Coronavirus disease caused by SARS-CoV-2 virus

In addition to serious pulmonary and extrapulmonary manifestations of the infectious coronavirus disease caused by the SARS-CoV-2 virus (COVID-19), the pandemic has resulted in significant mental health effects.¹ Public health measures introduced to curb the spread of the coronavirus, such as self-isolation, quarantine, lockdown and social distancing, have restricted physical activity and social contact. As a consequence, many people have experienced a decline in well-being, an increase in psychological stress as well as feelings of isolation, depressed mood and anxiety,^2,3 with common mental disorders being major adverse effects.^1,4 Common mental disorders, comprising different types of depression and anxiety, cause marked emotional distress and interfere with daily functioning, while they do not usually affect cognition or insight. The mental health effects of the pandemic may shape the health of entire populations for many years to come. Failure to address these mental health issues is likely to prolong their impact. Mental health experts have therefore emphasized the importance of developing approaches to supporting mental health at the population level.

Available evidence suggests that dietary factors and physical exercise should be considered in the promotion of mental health and the prevention of mental illness.⁵ These factors may also contribute to shifting the population distribution of infection risk and preventing severe outcomes of COVID-19.6, 7, 8 For example, a systematic review and meta-analysis of observational studies has found evidence for associations between ultra-processed food consumption and adverse mental health, with greater consumption of ultra-processed food being associated with elevated odds of depressive and anxiety symptoms.⁹ Furthermore, various nutrients and food bioactive have been proposed as effective measures in the management of common mental disorders.^10,11 However, evidence of their clinical efficacy is lacking^12,13 and their long-term administration may even be harmful.¹⁴

The large-scale disruptions to physical activity during the pandemic have been found to be a leading predictor of depression. At the onset of the pandemic, average steps per day in young adults plunged from around 10 000 to 4 600¹⁵ and the proportion of young adults at risk for clinical depression ranged from 46% to 61%, which represented an increase by 90% compared to the pre-pandemic rates.¹⁵ Beneficial acute and chronic effects of exercise on the immune system have been demonstrated,¹⁶ and regular physical activity has been promoted by the World Health Organization as a non-pharmacological and cost-effective approach to supporting mental health during the COVID-19 pandemic.^6,17 Empirical evidence suggests that regular exercise is effective in maintaining or improving well-being and mental health¹⁸, and exercise has also been found to alleviate anxiety, sadness and depression during the coronavirus pandemic.^19,20 This, together with the large number of studies published before the pandemic on the effects of physical activity on mental health,21, 22, 23, 24, 25 should be considered in the provision of mental health care following the pandemic.

The enhancement of physical health affected by exercise has been widely investigated, and regular exercise has been shown to be a key factor in good health.²⁶ Physically active individuals have been found to benefit from improved levels of health-related fitness, reduced risks of developing a wide range of disabling chronic conditions, including obesity, diabetes, cardiovascular disease, stroke and cancer, and a decrease in overall mortality.²⁷ The health benefits of exercise have also been widely acknowledged to encompass mental health. A cross-sectional study of more than 1.2 million adults in the United States, matched for various sociodemographic and physical health factors, found that people who exercised reported 1.49 (43.2%) fewer days of poor mental health in the past month than people who did not exercise, with all types of exercise and sport being associated with a reduced mental health burden.²⁸ The largest significant associations were for periods of exercise lasting 45 min and exercise performed 3–5 times per week as well as for popular team sports, cycling, aerobic and gym activities.²⁸ Engaging in sports involving interaction with other people may improve social confidence and skills and thus promote positive interpersonal relationships and psychosocial development.

While the association between physical activity and mental health is well established, causation remains a matter of debate. Unmeasured factors closely related to physical activity may play a role. In view of the social context of physical activity, the interplay between exercise and social interactions or other lifestyle habits may impact mental health. Disturbances of both mental well-being and physical activity may be influenced by a third variable, such as people's response to the pandemic. Individuals capable of maintaining their lifestyle during the pandemic may be better able to preserve their mental health and well-being. Before the pandemic, these individuals may have been more resistant to stress and less prone to depressed mood or anxiety.²⁹ Reverse causation is also possible, with physical activity being driven by mental health rather than lifestyle. For example, changes in lifestyle could be early signs of depression. Establishing a causal relationship between exercise and mental well-being and health requires randomized controlled trials demonstrating the beneficial effects of exercise interventions.

Depression has become the leading cause of the burden of disability globally.³⁰ Since the ability of pharmacological and psychological therapies to mitigate the cumulative burden of depression on society is limited,³¹ there is an urgent need to find modifiable factors that could become targets of health campaigns at the population level. Since adults with major depressive disorder have been reported to engage in low levels of physical activity and high levels of sedentary behavior,³² lifestyle interventions targeting the adoption and maintenance of exercise may be warranted. The debate surrounding the effects of physical exercise on depression has often been contentious, leading to uncertainty regarding the magnitude of these effects. Meta-analyses of randomized controlled trials have reported moderate to large antidepressant efficacy of exercise.33, 34, 35, 36 The varying effect sizes reported may have been influenced by inclusion criteria, heterogeneity of samples and diagnostic criteria as well as publication bias. Furthermore, various studies compared exercise in addition to an established therapy versus an established therapy alone.³³ This approach assumes that the efficacies of treatments can be added and subtracted algebraically. However, this assumption does not take into account that exercise may at least partially overlap and interact with the mechanisms underlying pharmacological and psychological therapies of depression.³⁷ In a meta-analysis adjusting for publication bias, large antidepressant effects of exercise on depression were found in comparison with non-active control conditions.²⁴ The effect was particularly high for studies including people with major depressive disorder. Larger effect sizes were also found in patients with a diagnosis of depression but without other clinical co-morbidities. In the context of the high risk of social isolation in older individuals with depression,³⁸ group exercise appears to be particularly effective. Future studies should therefore address exercise as a means of promoting social interaction. The question of whether exercise in combination with a conventional treatment produces better results than exercise or the other treatment alone remains at present a matter of debate owing to the limited data available. Furthermore, the currently established meta-analytic evidence showing the antidepressant efficacy of exercise in clinical settings, with relatively low attrition in people with major depressive disorder, needs to be complemented by randomized controlled trials providing ecological (i.e. real-life) evidence. These trials should examine the effectiveness of exercise interventions, defined as benefits produced in daily clinical practice, using wide inclusion criteria and functional health outcomes, such as quality of life. Exercise programs have also been proposed as a promising means of protecting against the development of depressive symptoms in young people,³⁹ which may be particularly helpful since they are non-stigmatizing and have few side effects.⁴⁰ Anxiety and depressive symptoms in adolescents have been found to be higher for low physical activity compared to moderate and high physical activity.⁴¹ Furthermore, some evidence from randomized controlled trials suggests a moderate positive effect of exercise interventions on the severity of adolescent depression.^42,43

Anxiety disorders are the most prevalent mental disorders in the general population⁴⁴ and have a significant societal and economic impact.⁴⁵ Epidemiological findings suggest that individuals who are more physically active may be less likely to suffer from anxiety disorders.^41,46 Current evidence, presented in several systematic reviews and meta-analyses, suggests that engaging in physical activity and sports may protect against anxiety symptoms and disorders across the lifespan.^23,47, 48, 49, 50, 51, 52 Higher-intensity exercise regimens may be more effective than low-intensity exercise.⁴⁹ Physical exercise as an add-on to cognitive behavioral psychotherapy appears to be feasible and beneficial, especially when performed regularly several times per week over extended periods of time.⁵² While exercise may be a viable option for the therapy of anxiety, the evidence for its effectiveness in anxiety disorders is equivocal and limited by a lack of data from methodologically rigorous randomized controlled trials with large sample sizes. Major limitations of the available studies include non-representativeness of samples, inadequate assessment of fitness and adherence levels, inconsistent adjustment for putative confounders, attrition bias and issues regarding exercise exposure and outcome measures. The available evidence is therefore insufficient to warrant a recommendation of exercise as a treatment in people with anxiety disorders. Nevertheless, in view of preliminary findings suggesting exercise as a useful, accessible and affordable therapeutic option for anxiety, further high-quality, long-term randomized controlled trials using robust experimental designs are called for. The lack of large samples and statistical power does not allow for the examination of exercise form, frequency, duration or intensity. It would be important to know whether certain types of exercise have advantages over others or whether an individual's favored sport can be chosen.

Mental health benefits of exercise and sport may be related more to the context of physical activity than the behavior of being active itself.53, 54, 55, 56 For example, participation in team sports and informal group activities has been reported to be inversely associated with depressive symptoms in comparison with individual physical activity.⁵⁷ Furthermore, team sports appear to be associated with positive mental health regardless of the volume of physical activity.⁵⁷ This suggests that features of the team sport context provide benefits to mental health and that increasing the volume of physical activity has no beneficial effects. The context of team sport is thought to be beneficial to mental health since it offers an opportunity for social interaction, thereby strengthening social networks and perceived feelings of support and integration.57, 58, 59

An umbrella review of systematic reviews and meta-analyses found a small positive impact of participation in organized sports on mental health in children and adolescents.⁶⁰ This was not related to any specific type of organized sport activity. The findings of a recent study from Canada using a large and diverse sample of high school students suggest that sport participation should be promoted for the prevention and management of adolescent mental illness.⁶¹ Students participating in varsity sports were found to have lower symptoms of anxiety and depression in comparison with nonparticipants, with associations being strongest in those who participated in both varsity sports and sports outside school. Another recent study including data from over 11 000 children and adolescents in the United States reported that participation in team sports compared to no sport participation was associated with fewer mental health difficulties, while participation in exclusively individual sports was associated with greater difficulties.⁶² These findings suggest that team-based organized sports may be a means to support youth mental health. However, given the cross-sectional design of the study, the causal relationship between participation in organized sport activities and mental health remains to be established.

The physiological and biochemical mechanisms discussed to be involved in mediating the effects of exercise on mental health include, among others, endorphins,⁶³ myokines,⁶⁴ inflammation⁶⁵ and stress modulated by the hypothalamic-pituitary-adrenal axis. The impact of stressful life events on mental health in general and major depressive episodes, in particular, has been firmly established.^66,67 An increase in the prevalence of stress, anxiety and depression in the general population has been observed during the COVID-19 pandemic.^68,69 Exercise interventions may improve the ability to deal with psychological stressors during and after the pandemic, since increased physical activity and fitness levels appear to be associated with an attenuated response to psychosocial stress.⁷⁰ Exercise may therefore exert its beneficial effects on mental health through stress-buffering mechanisms.⁷¹ Furthermore, physical activity seems to be capable of modulating stress-induced changes in DNA methylation and gene expression, with positive epigenetic influences of exercise counteracting the negative influences of stress.⁷²

Changing an inactive lifestyle and increasing physical activity is a challenge for many people. The outcomes of introducing a physical exercise regimen may be improved when various strategies are combined.^73,74 Such strategies include starting with short periods of physical activity,⁷⁵ improving self-regulation,^76,77 strengthening non-conscious processes,⁷⁸ improving accessibility to environments and facilities^77,79 and using internet and smartphone apps.⁸⁰ Maintaining a physical exercise regimen presents a further problem, since adherence to short-term prescribed exercise has been found to drop to 50% within six months.^81,82 Failure of practitioners to provide specific exercise recommendations is common.⁸³ Rates of adherence to exercise regimens can be enhanced when written prescriptions provide a detailed exercise plan, and suggestions for overcoming anticipated potential barriers are given.⁸⁴ The effects of exercise counseling may be facilitated through pre-intervention educational programs, continued motivational support and improving the convenience of exercise facilities and opportunities.^85,86 Furthermore, increased drop-out rates have been found in groups undertaking high-intensity training compared to low-intensity programs.⁸⁷ Given the higher efficacy of high-intensity programs, exercise regimens need to be individually tailored in order to maximize the beneficial effects of exercise while minimizing the drop-out rate.

Exercise has long been underestimated as a variable contributing to mental health, and lessons from the current pandemic regarding mental health care include the value of physical exercise and sport in the management of common mental disorders. The findings of numerous studies support the antidepressant and anxiolytic efficacy of physical exercise and sport, indicating their promise as additional or alternative options for managing anxiety and depressive disorders. Physical exercise as a therapeutic option is relatively free from side effects and produces additional benefits for physical health, such as a decrease in blood pressure and weight loss. The potential improvement in mental health resulting from lifestyle changes incorporating increased physical activity should therefore be considered in the therapy regimens of individuals and in population-wide public health programs. Further interventional study of sustainable exercise effects in individuals with depression and anxiety is required to identify the specific types and optimum frequency, intensity and duration of physical activity. The financing of high-quality studies investigating the effects of exercise on mental health will pose challenges, since immediate pecuniary returns from such investigations cannot be expected. However, long-term gains include amelioration of the burden of mental illness and additional physical health benefits in respect of cardiovascular and metabolic diseases. Political interventions, public funding and support through non-profit organizations will be needed to help counter the challenges faced in the fostering and maintenance of public health. In addition to specialist care, task-shifting may be capable of providing cost-effective and sustainable mental health care worldwide, especially where health services are overwhelmed by the pandemic.⁸⁸

In conclusion, the effectiveness of exercise and sport participation in sustainable mental health care as well as the causal relationship between exercise, psychosocial health and common mental disorders merit further investigation. Physical activity and sport, with their global accessibility, significant and clinically meaningful efficacy as well as the virtual absence of adverse effects, offer a promising, evidence-based option for the prevention and treatment of common mental disorders. Any increase in physical activity should therefore be encouraged by health practitioners in order to improve mental health. Physical exercise and sports are likely to become valuable public mental health resources in the future.

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The work described has not been published previously, is not under consideration for publication elsewhere, its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and, if accepted, it will not be published elsewhere including electronically in the same form, in English or in any other language, without the written consent of the copyright-holder.

Authors' contributions

KWL contributed substantially to the conception of the work, drafted the work, provided approval for publication of the content and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. YN contributed substantially to the conception of the work, revised it critically for important intellectual content, provided approval for publication of the content and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. AR contributed substantially to the conception of the work, revised it critically for important intellectual content, provided approval for publication of the content and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.