Exercise and Immunity – How to Exercise to Get Sick Less Often?

Immunity is “in our blood”

Our resistance to infections is closely linked to the work of the circulatory system, because its efficiency determines the body’s ability to respond to pathogens. Physical activity not only increases the efficiency of our cardiovascular system, but also contributes to a more effective functioning of the body’s natural lines of defense – the cells responsible for fighting pathogens are present in greater numbers and get to the right place faster. In addition, studies show that:

• physical activity increases the number and activity of macrophages, the cells that form the first line of defense, which in active people more effectively engulf bacteria and viruses,
• in physically active people, higher activity of specialised white blood cells – Th lymphocytes, which support and modulate the body’s immune response, was observed,
• increased leukocyte activity translates into an increase in blood concentrations of IgG and IgM antibodies and other chemicals that support the body’s defense responses.

This is in line with studies that confirm that moderate but regular physical activity can reduce the risk of infection by up to 43%. So, to get sick less often, you need to exercise more. Since immunity originates in the circulatory system, the most effective way to support it is through aerobic exercise.

What else supports our immunity?

Other insights into the relationship between physical activity and resistance to infections are based on fairly simple, though not always obvious, conditions surrounding exercise. The increase in body temperature during exercise means that the growth of harmful bacteria is inhibited. In addition, outdoor workouts provide our bodies with temperature stimuli that directly affect blood circulation, and also support the natural synthesis of vitamin D, the production of which requires UV radiation, or sunlight.

What is more, when you exercise outdoors, your immunity is boosted by health-friendly chemicals present in the soil, which are produced by plants and animals. Training outdoors supports our exposure to substances that have been with us “since time immemorial” and have been vital to the survival of our species.

It is also worth mentioning the basic elements related not only to physical activity, but to a broader lifestyle. A balanced diet rich in vitamins (A, C, E, D) and minerals (zinc, selenium, iron), which are responsible for the proper functioning of the immune system, is key. Adequate quantity and quality of rest is also very important – excess hormones accompanying exercise and stress (adrenaline, cortisol) inhibit the activity of white blood cells.

Finally, it is worth mentioning hygiene. While it seems obvious that attention to adequate hygiene reduces the presence of harmful microorganisms (which in turn reduces the likelihood of infection), an overly strict approach to body cleanliness can disrupt the proper functioning of the natural bacterial flora. Paradoxically, this can increase the body’s susceptibility to diseases.

Being active helps – but not always!

We stressed earlier that even moderately intense but regular physical activity reduces the risk of disease. So can more intense, prolonged training take our immunity to an even higher level? Quite the contrary! Athletes who train longer and more intensively were found to have a higher risk of infection than moderately active people. Particularly vulnerable are long-distance runners, whose risk of upper respiratory tract infections is many times higher.

High-intensity exertion is associated with disruption of the natural respiratory rhythm and greater exposure to pathogenic microorganisms present in the air. Adrenaline and cortisol “block” our defense system, reducing the activity of white blood cells. After such an effort, the body focuses on restoring homeostasis compromised by training stimuli. All of this results in post-workout weakness, which can persist for several to even dozens of hours in cases of extreme stress. Therefore, with intense exercise, proper recovery is extremely important.

How to train to get sick less often?

If physical activity is to improve the body’s immunity, it must be properly matched to our individual physical and environmental conditions. For many people, moderate-intensity aerobic exercise performed for 45 minutes 3-4 times a week will be a good option. However, in order to arrange an optimal training plan, it is best to take advantage of individual consultations with a trainer.

We also caution against exercising during an infection. For mild, unproblematic symptoms (runny nose, sore throat), moderate-intensity exercise can be helpful because of the increase in body temperature and faster blood circulation. However, when you suffer from muscle and joint pains, fever or problems breathing freely, exertion can worsen your condition. Also, remember to refrain from participating in group activities during an infection!

_References:

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6. _{Nieman D. C., Henson D. A., Austin M. D., Sha W., Upper respiratory tract infection is reduced in physically fit and active adults, British Journal of Sports Medicine, 2011.}
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9. _{https://www.bbc.com/future/article/20220929-how-outdoor-play-boosts-kids-immune-systems, dostęp: 26.09.2024.}
10. _{https://www.health.harvard.edu/staying-healthy/5-surprising-benefits-of-walking, dostęp 23.09.2024.}