Moderate physical exercise, if performed consistently, is able to regulate the immune system, avoiding both situations of chronic inflammation and excessive inflammation. This emerges from a very recent scientific research that appeared in the American journal of physiology, Cell physiology, published by a Canadian team from York University in Toronto (Murugathasan et al, Am. J. Physiol. Cell Physiol, Jun 2023).
Good inflammation and bad inflammation
Inflammation is our defense mechanism against the attacks of bacteria, viruses, fungi and in general against anything that is recognized as a threat. Here the inflammation flares up like a fire with the aim of regenerating damaged tissues and healing from any infections. But when the threat has passed, the inflammation must also cease. This does not always happen, especially in the presence of an unbalanced diet, sedentary life, stress, obesity, disturbed sleep, intestinal dysbiosis, the intake of some medicines and chronic infections. In these cases, it is possible that the inflammation does not go away but remains chronic and at a low level. In these cases, the symptoms are not visible, at least not immediately. Over time, however, if chronic inflammation persists and is not properly countered, it can increase the risk of certain conditions, such as cardiovascular and neurodegenerative diseases, depression, tumors, sarcopenia, diabetes and fatty liver. Not only that, sometimes the body's response to an infection is so sudden and acute that the inflammation becomes excessive. This too can cause significant damage, just think of COVID 19. In some people, the infection can generate an out-of-control inflammatory response, with a consequent accumulation of fluids in the lungs and an increased risk of blood clots. What has been said shows the importance of being able to modulate inflammation, counteract chronic inflammation and avoid an excessive response in case of infection.
The role of exercise
It is well known that exercise helps regulate the inflammatory response and counteract chronic inflammation. However, until now, studies have focused on the immediate effects, showing a boost in the immune system immediately after exercise. Instead, as emerges from the research we are talking about today, the benefits of physical exercise also seem to act in the long term and show that physical activity not only trains the body but also our immune system to respond in a "healthier" way to threats and avoid a situation of chronic inflammation. But let's try to understand better.
Moderate physical activity educates the immune system, the study
The study took place in the laboratory on a population of mice. Half of the mice did regular moderate physical activity, running on a treadmill for an hour a day, every day for 2 months. The other half, on the other hand, did not do any type of physical exercise. At the end of the experiment, the scientists analyzed the status of macrophages in the mice. Macrophages are white blood cells produced in the bone marrow and that play an essential role in the inflammatory process, both in terms of activation, maintenance and then subsequent shutdown of inflammation. Well, what happened after 2 months is that the mice that had followed an active lifestyle had a reduction in inflammatory markers and different macrophages compared to the mice that had led a sedentary life. In particular, macrophages, following regular and moderate physical activity, had reduced their inflammatory response. This was possible because exercise induced, over several weeks, a change at the cellular level, reducing free radicals in macrophages and changing how cells breathe, feed and access DNA, and consequently also how they behave in the face of threats, present or past. In general, an improvement in the quality of the macrophage mitochondria was observed. Mitochondria are organelles that deal with the production of energy within cells, but they are also involved in processes that control the activation of macrophages and therefore the inflammatory response.
Therefore, physical exercise trains macrophages to respond in a non-exaggerated way and helps to reduce chronic inflammation. However, the beneficial effects are connected to the constant practice of physical exercise. In fact, scientists have tested what happens when mice are put to rest. Well, after two weeks the macrophages returned similar to those of mice that had always led a sedentary life.
So physical exercise is able to educate our immune cells to have a more balanced inflammatory response in case of infection and a reduction of circulating pro-inflammatory substances in the absence of threats. The study is still in its infancy and much work needs to be done. In the first place, the scientists intend to study what happens in humans, even if the authors of the study say they are certain that what they observed in mice is replicable in humans, since the inflammatory process is ancient and therefore similar between the various mammals. More than anything else, the aim will be to test what type of physical exercise and with what intensity it should be practiced in order to improve and regulate the inflammatory response.
Then, the researchers also intend to understand the effects of exercise in the case of very complex infections, such as COVID 19, or autoimmune diseases that can stimulate an excessive inflammatory response.