What is immune fitness?

What is the immune system?
How does the immune system protect the body?
How is the immune system affected?
What is an adaptive immune system?
How can you increase immune fitness?
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An immune system that can adapt to a wide range of situations by creating, maintaining, and controlling an appropriate immune response is called immune fitness. This article will explore ways to increase immune fitness.

What is the immune system?

The immune system is made up of a complex network of organs, cells, and proteins that work together to keep the body healthy, fight disease, and speed the healing process after injury.

Innate and adaptive immunity are the two basic components of the immune system. When protective barriers such as the skin and mucous membranes are compromised, innate or “non-specific” immunity is the first line of defense against germs or pathogens.

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How does the immune system protect the body?

To defend against external threats like bacteria and viruses, as well as internal threats like cancer, the immune system uses a variety of strategies, known as innate and acquired.

White blood cells, including B and T cells, are also known as memory cells, as they keep a record of all the germs the immune system has ever fought off. This means that if the germ does re-enter the body, it can be quickly identified and eliminated before it has a chance to grow and make a person sick.

The body’s enzymes and immune cells called phagocytes (eg, neutrophils and macrophages) work together to clear invading infections due to innate immunity.

Antibodies and phagocytic cells are better able to identify and kill pathogens and damaged cells thanks to plasma proteins. Antimicrobial proteins in the mucous membranes of the oral and nasal cavities kill microorganisms before they have a chance to enter the respiratory tract and cause illness.

There are so many different viruses or strains of the same virus that can cause the flu and the common cold that they must be dealt with repeatedly. Having a cold or the flu does not make someone immune to other viruses.

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How is the immune system affected?

Immune function can be affected by both physiological and psychological stressors. The innate and acquired immune systems are influenced by physical activity.

Advancing age results in the steady decline of the immune system. As a result, the body’s immune system is less able to fight infections and form a long-term memory of them. Asthma, chronic obstructive pulmonary disease (COPD), diffuse interstitial disease, and respiratory infections in the elderly are related to a lack of oxygen in the bloodstream.

Viral envelopes and virus-infected cells can be destroyed by cytokines (interleukin [IL]) such as interferon. Natural killer (NK) cells are a type of lymphocyte that can quickly identify and destroy a malignant or diseased cell.

They do this by piercing the membrane of the target cell and injecting cytolytic granules into it, causing the cell to die. A few hours after exposure to a pathogen, the innate immune response can eradicate it from the body.

This response is advantageous because it can detect and react to a broad spectrum of bacteria. Because it lacks “memory” and cannot initiate a “targeted” immune response that leads to long-term protection, it is not ideal for long-term protection.

Related: How Does Stress Affect Your Immune System?

What is an adaptive immune system?

The adaptive immune system, sometimes called the acquired immune system, clears infections by limiting their spread.

Many infections evade the innate immune system, activating the adaptive immune system. This reaction “targets” the bacteria causing the infection and includes T and B lymphocytes. Although slower than the innate response, the adaptive response is more precise and successful in resolving infections.

The adaptive response causes many once-in-a-lifetime diseases. Because T and B cells “remember” infections, they can survive forever. They can also induce a more rapid and particular immune response, in case of recurrence of the infection.

Vaccination prevents disease by “educating” the adaptive immune system so that it can respond quickly if exposed to the infectious agent in the future. Both the innate and adaptive immune systems can operate synergistically in the total immune response.

Adaptive immune cells produce cytokines and other chemical messengers that govern the activity of innate immune cells. Both arms of the immune system are involved in inflammation.

How can you increase immune fitness?

Exercise changes both the innate and acquired immune systems. The neuroimmune-endocrine system mediates changes in the number and function of circulating leukocytes. Acute exercise can increase stress hormones, inflammatory cytokines, oxidative stress, and T cells, NK cells, neutrophils, and macrophages.

Regular exercise reduces inflammatory cytokines and oxidative stress and increases the resting function of immune cells. Strenuous exercise increases muscle inflammation and leads to delayed-onset muscle injury.

Exercise-induced mechanical stress promotes the release of immunoregulatory proteins, including myokines. Skeletal muscle cells release myokines without causing inflammation. Exercise-induced fat loss reduces inflammatory adipokines. Changes in cytokine release from metabolic organs alter circulating leukocytes and immunologic activity in other organs.

Immune function varies in response to acute and chronic exercise and affects physiological and pathological states such as fatigue, exercise performance, and risk of infection. Diet affects these elements of the immune response. In addition to key nutrients, phytochemicals can reduce immune suppression and inflammation after intense exercise.

Exercise has a dramatic influence on the immune system and helps the elderly, those with cancer, obesity, inflammatory diseases, diabetes, and persistent viral infections (eg, HIV).

Healthy adults with appropriate BP levels maintain optimal immune function and avoid immune decline with age and obesity. Avoiding sedentary behavior and meeting PA standards through regular exercise can help preserve immune health in most people.

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  • Aoi, W. and Naito, Y. (2018) ‘Immune function, nutrition and exercise’, Nutrition and improved sports performance: muscle development, endurance and strength, p. 83–95. doi.org/10.1016/B978-0-12-813922-6.00007-2.
  • Baker, FL and Simpson, RJ (2021) ‘Exercise to support optimal immune function’, ACSM Health and Fitness Magazine, 25(1), pp. 5–8. doi.org/10.1249/FIT.0000000000000628.
  • Lindberg, S. (2022) Does exercise boost immunity?, health line. Available at: https://www.healthline.com/nutrition/does-exercise-boost-immune-system (Accessed: July 4, 2022).

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