Physical activity is recommended for physical health and to prevent certain diseases. But the positive effects of physical activity on well-being, cognitive abilities (e.g. memory or decision-making), emotion regulation and mental health in general are also well documented. For example, exercising reduces symptoms of anxiety, depression, stress and loneliness.
However, many questions remain unanswered: Do the positive effects of physical activity on mental health and cognitive abilities affect all sports, whether intense or moderate, individually or collectively? Can physical activity be unfavorable? Through what biological mechanisms do these effects occur? Are they present in all subjects? The aim of this article is to provide some answers to these questions.
Does the positive effect of exercise on mental health depend on the intensity of the effort?
If we take into account the intensity of physical exertion, we distinguish two sports. The former, like walking or jogging, require endurance. They mobilize between 65% and 80% of the subject’s maximum heart rate (HRmax). These activities are said to occur in aerobic zones because the body uses oxygen to release the energy necessary for exercise.
The second involves more intense efforts, such as sprinting. They mobilize 85 to 90% of the maximum heart rate by producing lactic acid, a compound that is necessary for muscle function but can cause cramps when in excess. These sports are located in an anaerobic zone, i.e. without the use of oxygen to generate energy.
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It has been clearly proven that aerobic activity, which requires endurance and lasts about twenty minutes, is enough to improve cognitive functions in adolescents. However, the beneficial effects are not limited to aerobic (endurance) sports. In fact, strength training, a popular strength training technique used by bodybuilding enthusiasts, results in similar effects on cognition.
Other studies have focused on more specific sports. They show that, for example, karate or taekwondo improve concentration and what we call executive functions (i.e. high-level cognitive processes such as planning, strategy development, mental flexibility), that table tennis plays on the anticipation of action and reaction time, or so dancing promotes well-being. Sport is therefore fundamentally beneficial, but the type of sport practiced can be crucial for the development of certain cognitive dimensions.
Read more: Yoga changes the brain and improves mental health
Can physical activity be unfavorable in certain situations?
However, exercise can also pose health risks for people. Top athletes and fans of high-intensity sports (marathon, triathlon, Iron Man, CrossFit, etc.) train for many hours and push their bodies to the limits of their limits. These practices can also be a risk factor for addictive behavior, with addiction to exercise increasing the risk of developing another addiction, for example to a substance such as alcohol.
Do individual and team sports have the same effect?
Several studies show that participating in a sports team during adolescence reduces stress and improves participants’ mental health and social integration. This effect is not systematically determined for the practice of individual sports; some studies even report negative effects. This work appears to suggest that participating in a team sport has a greater positive impact on mental health than playing individual sports. One of the mechanisms through which team sports promote mental health is, for some authors, linked to the fact that collective action makes it possible to build social and friendly relationships and to promote the sense of belonging to a group, which is crucial for mental health, especially in adolescence .
Read more: Is physical education and physical education just about playing sports?
However, the context in which these activities are carried out and individual factors also play an important role. In fact, certain conditions, for example intense competitive contexts with extreme training, coaching styles that emphasize winning, or immoral means of achieving this, have negative effects on mental health and lead to stress, burnout and addiction.
Through what biological mechanisms does exercise affect well-being and mental health?
Brain imaging studies have found a positive association between exercise and increases in the volume of certain brain areas such as the hippocampus, an important region for memory encoding (the process by which memorization occurs) and coping with stress. In particular, regular tennis training also improves the function of the prefrontal regions, a region that is crucial for executive functions.
When we look at this phenomenon at the cellular level, we find that the positive effects of endurance activity (aerobic activity) are associated with an increase in what experts call adult hippocampal neurogenesis.
In fact, it has been shown that new neurons are generated every day in the hippocampus of an adult subject. These promote memory and stress resistance. When a squirrel wheel is introduced into the mouse breeding cage, they spontaneously begin performing aerobic exercise (endurance exercise). If we compare the brains of mice that performed this type of effort regularly and sustainably with those of sedentary mice, we see a significant increase in neoneurons in the hippocampus.
Several mechanisms have been proposed: Exercise increases cerebral blood flow and brain oxygenation. Neurotrophic factors are also released, i.e. factors that promote the growth and survival of neurons. In addition, mice can be exposed to intense physical exertion interrupted by short periods of rest. Studies initially seemed to indicate an unfavorable effect of anaerobic training. However, recent studies have shown that this type of exertion also has a positive effect on the creation of new neurons by the hippocampus (hippocampal neurogenesis), undoubtedly through the release of neurotrophic factors by the muscles.
Do these effects exist for everyone?
In studies on animals, but also on humans, the positive effects of physical exertion on cognition, well-being and the formation of new neurons by the hippocampus (hippocampal neurogenesis) are not present in all subjects and vary depending on their genetic background. In fact, certain gene variants that encode neurotrophic factors (like BDNF) or growth factors (like NGF) reduce the beneficial effects of exercise.
In summary, we find that all of these studies confirm and illustrate the positive effects of physical activity on mental health and well-being. They emphasize the extent to which the body and cognitive, emotional and social processes are in constant interaction. In addition, physical exercise, often practiced in teams, also promotes social integration and becomes a powerful catalyst for a more inclusive society.
This article is published as part of the Science Festival (held from 6 to 16 October 2023 in mainland France and from 10 to 27 November 2023 overseas and internationally) and of which The Conversation France is a partner. The focus of this new edition is on the topic of “Sport and Science”. Find all the events in your region on the Fetedelascience.fr website.