Escape the cold: how sport affects immunity

It is known that a healthy lifestyle has an impact not only on the body as a whole, but also on the state of immunity. It is logical that the healthier and stronger a person is physically, the less susceptible he is to diseases and colds. However, what role does sport play in this? And is it possible to strengthen immunity with the help of training? Let’s find out together with scientists.

How does physical activity affect immunity?

Employees of the University of Iowa, USA in 2009 conducted an experiment to find out how exercise affects the immune system. Three groups of mice were selected for the study. The first group was not given any additional loads, the second group was moderately “exercised” for 14 weeks, and the third group made a 45-minute “jog” before the experiment. After that, all the mice were infected with the influenza virus.

As the scientists expected, the mice with good physical fitness showed higher resistance to the disease, and they showed fewer symptoms. The results of the third group were better than the first, but the effect of irregular exercise was also short-lived. That is, physical activity had a positive effect on the state of immunity.

Similar conclusions were reached at the University of North Carolina. In the study, 1002 adults from 18 to 85 years old reported on their well-being for 12 weeks – at the height of the flu season. In addition, the subjects also noted their activity levels. As a result, those who exercised five times a week or more were 43% less likely to experience flu symptoms than those who exercised one or fewer times.

What kind of exercise should you choose?

However, whatever the positive effect of exercise, it should be moderate. This is confirmed by a series of experiments conducted at the University of Illinois in 2005. Scientists divided experimental mice into three groups. Individuals from the first led a sedentary lifestyle, from the second – “exercised” 25-30 minutes a day, and from the third – daily “trained” for 2.5 hours.

After infection with influenza virus, the least number of survivors (30%) was in the last group, which was subjected to intensive exercise. Of those mice that practically did not move, recovered 43%, but in the second group to overcome the disease managed 83%.

Similar results are reported in Alex Hutchinson’s book “Cardio or Strength”. During the preparation for the marathon in Los Angeles, researchers observed 2300 runners. It turned out that those who ran more than 95 kilometers a week in training had an increased risk of catching a cold.

Why can intense exercise be harmful?

It is not known for sure why high exertion, on the other hand, is bad for the immune system. Perhaps while moderate exercise helps delay inflammation, intense exercise temporarily weakens the body, slowing the immune response.

In 2016, a team of scientists from Brazil and the United States found that intense exercise two days in a row leads to lower immunity. After crossfit, subjects were noted to have lower levels of cytokines – anti-inflammatory cells.

Physical activity can indeed strengthen the immune system and help reduce the risk of infection during flu season. However, for exercise to be beneficial and not harmful, it must be regular and moderate, and the importance of recovery should not be overlooked.