Physical Activity for Cognitive and Mental Health in Youth

World Health Organisation (WHO) recommended levels of physical activity for children aged 5 - 17 years should accumulate at least 60 minutes of moderate- to vigorous-intensity physical activity daily. This is beneficial for both mental and physical health.
For children and young people, physical activity includes play, games, sports, transportation, chores, recreation, physical education, or planned exercise.
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Physical activity can improve cognitive and mental health, but the underlying mechanisms have not been established.

Lubans et al conducted a Systematic review with the objective to present a conceptual model explaining the mechanisms for the effect of physical activity on cognitive and mental health in young people and to conduct a systematic review of the evidence.

The conceptual model includes 3 broad potential mechanisms

• Neurobiological
• Psychosocial
• Behavioural

Neurobiological Mechanisms

The neurobiological mechanism hypothesis proposes that participation in physical activity enhances cognition and mental health via changes in the structural and functional composition of the brain.

In a review 3 broad categories of neurobiological mechanisms responsible for cognitive functioning, involving changes in the central nervous system:

(1) cells, molecules, and circuits that, with current scientific techniques, are only detectable in animal studies (eg, neurogenesis);

(2) biomarkers (eg, grey matter volume, cerebral blood volume, flow); 

(3) peripheral biomarkers (eg, circulating growth factors, inflammatory markers) that can be observed in humans.

Participation in physical activity is believed to lead to the release of endorphins, which can ease pain and produce a feeling of euphoria. However, there is little empirical evidence to support this assertion. It is unknown if the short-term pleasure that individuals experience during physical activity is due to endorphins and to what extent this action contributes to improved mental health in young people over time.

The “feel good” effect of activity may be due to changes in 1 or more brain monoamines, with the strongest evidence available for dopamine, noradrenaline, and serotonin.

Psychosocial Mechanisms

• Physical activity has the potential to improve well-being via a range of psychosocial mechanisms. Several theoretical frameworks propose that well-being is achieved by satisfying basic psychological needs for social connectedness, autonomy, self-acceptance, environmental mastery, and purpose in life
• Participation in physical activity may lead to improved task self-efficacy (i.e., one’s confidence in their ability to perform specific activities), which generalizes first to broader physical self-concept and then to global self-esteem.

However, physical activity may also have a negative impact on mental health outcomes among children and adolescents in certain contexts and circumstances. For example, poorly designed and delivered physical education lessons may thwart students’ needs satisfaction and lead to decreases in perceived competence and global self-esteem. Similarly, participation in physical activity may also influence physical self-perceptions within the appearance subdomain (eg, perceived attractiveness, body image).
 
Short-term experimental studies have shown

• Promising effects on self-reported well-being immediately after exercise in natural environments, which are not seen after the same exercise indoors.
• These findings are grounded in the theory that humans are biologically predisposed to be attracted to nature and have spent the majority of their evolutionary history in natural environments.
•  Among adults, connectedness to nature has been found to be positively associated with mental health outcomes.  In addition, the restorative properties of natural environments may explain why participation in physical activity in natural environments has mental health benefits.

 
Behavioural Mechanisms

The behavioural mechanism hypothesis proposes that changes in mental health outcomes resulting from physical activity are mediated by changes in relevant and associated behaviours.

Participation in physical activity may improve sleep duration, sleep efficiency, sleep onset latency and reduce sleepiness.
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In addition, participation in physical activity programs may also influence self-regulation and coping skills that have subsequent implications for mental health.
 
Conclusions

Systematic reviews and meta-analyses have shown that physical activity interventions can improve cognitive and mental health in young people, but the review identified a lack of available evidence for the specific mechanisms responsible for these effects. The review did establish that participation in physical activity can improve physical self-perceptions and enhance self-esteem in young people.

The findings highlight several important gaps in the research literature and emphasise the need for more high-quality experimental research to examine the specific paths of influence between physical activity participation and improved mental health.

Future studies should conduct statistical mediation analyses, using the conceptual model provided herein as a framework. Improving our understanding of how physical activity improves mental health in child and adolescent populations may assist in the design of interventions to optimise their possible impact on these critically important outcomes.

Finally, elucidating the mechanisms underpinning the effect of physical activity on cognition, well-being, and ill-being may provide the necessary impetus for schools, governments, and policy makers to prioritise physical activity promotion.

References
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• ​Lubans et al (2016). Physical Activity for Cognitive and Mental Health in Youth: A Systematic Review of Mechanisms. Pediatrics.
• Rodriguez-Ayllon M, et al (2019). Role of Physical Activity & Sedentary Behaviour in The Mental Health of Preschoolers, Children & Adolescents. A Systematic Review & Meta-Analysis. Sports.PMID: 

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