The Myth behind Exercise-Induced Immunosuppression.

Physical exercise has a powerful effect on our bodies. Most of the exercise benefits can be measurable such as body composition modification and physical endurance. However, it is common to hear athletes talk about how exercise influences their immune responses. Indeed, nutrition and exercise immunology go hand in hand to modify immune function. Immunonutrition combines the anti-inflammatory components of orthomolecular medicine to counteract exercise-induced immunosuppression. Combining the provision of an adequate amount of macro and micronutrients and the immunological modulation by oligo-elements, antioxidants, probiotics, fiber, and fatty acids improves the inflammatory response and reflects better athletic performance.

Exercise-induced immunosuppression

Nutritional anti-inflammatory components act in a different way on athletes than those obese or sedentary individuals. Indeed, the exercise component and the body composition difference, exercise exerts other benefits in athletes compared to their sedentary counterparts.

Exercise-induced immunosuppression defines how inappropriate exercise regimens and training programs affect immune function and promote illnesses. The science behind this relies on nutritional bioactive compounds that support and restore immune functions. Also, nutrient-dense dietary programs and supplementation are often used to counteract this exercise-induced immunosuppression.

Anti-inflammatory effects of exercise:

When an athlete trains with the basis of a proper exercise regimen, multiple anti-inflammatory benefits result from this practice. Furthermore, body composition modifications such as a low visceral fat content lead to a reduced release of adipokines. 

On the other hand, muscle enhancement, cortisol, and adrenaline secretion can reflect on elevated levels of “myokines.” Indeed, the release of IL-6 by the muscle cells promotes an anti-inflammatory milieu, improving athletic performance and endurance. Also, at a cellular level, the expression of Toll-like receptors (TLR) is reduced. In turn, this inhibits the downstream of pro-inflammatory cytokines.

Immune cells also change in number and quality within the adipose tissue. Consequently, a reduction of M1- type macrophages translates to lower TNF-a and IL-6, followed by increased numbers of M2- type macrophages that stimulate the production of anti-inflammatory mediators IL-10 and adiponectin.

Immune competency following exercise

The “open window” hypothesis was first reported in the decades of 1980 and 1990. Furthermore, this hypothesis is based on the following three supporting ideas and in the context of acute vigorous aerobic exercise:

• The risk of infection rises after an acute bout of vigorous aerobic activity.
• These intense activity levels can lead to a temporary decrease in salivary IgA, resulting in opportunistic infections.
• Immune suppression after strenuous exercise results in decreased levels of immune cells in peripheral blood, leading to high infection risk.

Investigators Campbell et al. refute this hypothesis by reporting exciting information on their research paper. These authors mention that it is relatively easy to declare “flu-like symptoms” after a marathon due to the high of assistants and if throat and nose swabs were not used as a part of detecting the URTI. Furthermore, they ensure that when diagnostic methods were used instead of self-reported symptomatology, only 30% of the athletes had an infection. In addition, salivary IgA always rose back to normal levels after 24h and was an inconsistent measure. 

Furthermore, they end their discussion by assuring that acute vigorous bouts and regular exercise stimulate immune function. In today’s world where vaccination is needed to counteract the COVOD-19 infection, exercise can play a crucial role in the immune response. Multiple studies show how intense to moderate exercise can improve the responsiveness to any given vaccine.

Exercise is a fundamental part of every treatment. It prevents cardiovascular and metabolic illnesses and improves body composition. However, everything done in constant repetition will have a repercussion. Therefore, preventing and reversing exercise-induced immunosuppression must be made after careful investigation of infection, nutrient depletion, and gastrointestinal assessment. Once again, combining the proper provision of macronutrients and the supplementation of bioactive compounds to protect our barriers is the best way to treat an exacerbated immune response. The truth is that every immune cell counts and infections are easier in a depleted body than in a healthy one.- Ana Paola Rodríguez Arciniega

References:

Bermon, Stephane et al. “Consensus Statement Immunonutrition, and Exercise.” Exercise immunology review vol. 23 (2017): 8-50.

Campbell, J. P., & Turner, J. E. (2018). Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan. Frontiers in immunology, 9, 648. doi.org/10.3389/fimmu.2018.00648

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