Why aerobic exercise affects the brain like this: the reason for evolution

    Over the past decades, numerous studies have shown a positive effect of aerobic training on mental abilities throughout life ( 1 , 2 , 3 , 4 ). Particularly important effects have been noted for an aging brain. The benefits of them are undeniable - both for healthy people and those suffering from neurodegenerative diseases like Alzheimer's disease. But despite the growing interest in running for therapeutic purposes, science still does not quite understand the mechanisms by which cognitive abilities of a person are improved so much. In addition, studies show a large difference in the results in different experiments.

    One of the reasons for the lack of a clear understanding of the mechanisms of the effect of aerobic exercise on cognitive abilities is the lack of a theoretical model of such an effect, say American researchers from the University of Arizona. Therefore, they set the task to create such a model and to understand the reasons for the individual differences in the effect of aerobic exercise. This is important for creating more effective individual training programs.

    To create a new model, scientists used an evolutionary neurological approach. They explain how physical activity acts on the brain in terms of human evolution. Scientists suggest that training is directly related to cognitive abilities, since as a result of evolution, a person about 2 million years ago adapted to the model of gathering, in which motor control, memory, spatial navigation and decision making are combined with a high level of aerobic physical activity. In simple words, our ancestors were all athletes with advanced stamina. They constantly moved, ran and walked, winding many tens of kilometers in a day.

    “We think that our physiology reacted to this increase in physical activity, and these physiological adaptations affected everything from your bones and muscles, apparently, to your brain,” said David Raichlen, associate professor at the School of Anthropology at College of Social and behavioral sciences at the University of Arizona. - It’s rather strange to think that the movement of your body should affect the brain in such a way - that the exercises have some positive effect on the structure of the brain and its functioning - but if you think about it from an evolutionary point of view, you will start to put the puzzle pieces together and understand why the system responds adaptively to the challenges and stresses associated with exercise. ”

    Using the concepts of evolutionary medicine, researchers propose a new Adaptive Capacity Model (ACM) that explains why exercise protects the brain throughout life. The key elements of this concept are indicated in the illustration above and are explained in detail in the diagram below.

    According to scientists, in the case of an inactive lifestyle that is familiar to modern society, the brain adapts and reduces cognitive abilities, obeying the most energy-efficient strategy. With age, this leads to brain atrophy.

    The authors of the scientific work outlined a range of specific areas of mental activity that are associated with active physical search for food and decision-making. They believe that this model can be considered the foundation for modern, more advanced research that can help preserve a person’s mental abilities throughout his life.

    In addition, this model helps explain why previous studies of the effects of aerobic exercise on cognitive performance have shown such different results. The reason is the difference in the cognitive tasks that the subjects posed, as well as the intensity and timing of the physical exercises — these factors are critical and affect the results of the tests.

    “Finding food is incredibly complex cognitive behavior,” says Reichen. - You move around the landscape, you use memory not only to decide where to go, but also to find the way back, you pay attention to the environment. This is a multi-tasking process along the entire path, because you need to make decisions and at the same time monitor the surrounding reality, and at the same time control your physical activity over rough terrain. If you put everything together, you get complex multi-tasking efforts. ”

    The evolutionary history of man shows that we are all athletes. And if you do not maintain activity at the proper level, the body will adapt to the new low-energy regime. In particular, the brain will be adhered, reducing its functional readiness, scientists say. They recommend intense aerobic exercise, constantly moving along new routes. The new environment provides extra warm-up for the brain.

    The scientific work was published in the July issue of Trends in Neurosciences (doi: 10.1016 / j.tins.2017.05.05.001, pdf ).

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