[Austin Both is the Associate Performance Director of Athletic Lab]

immune systemExercise, or physical activity in general, has quite a profound effect on the immune system that is often unrecognized or under-appreciated. Oftentimes, when we feel mildly ill or under the weather, we often choose to decrease our activity level as a result of diminished energy. Ironically, maintaining physical activity during a time of minor illness could be the key to getting back to fighting shape as quickly as possible.

The immune system is a complex beast that consists of two major components under the lymphatic system: nonspecific resistance, and specific immunity. For the sake of this article, we will be diving into nonspecific resistance. Exactly as it sounds, nonspecific resistance is the piece of the puzzle that protects from and attacks and foreign pathogens, regardless of pre-existing antibodies or previous exposures (Saladin, p. 829).

Exercise has multiple interactions with nonspecific resistance of the immune system, mostly due to the close interaction of the circulatory system and the lymphatic system. The first component, and likely the simplest aspect, is that increased blood flow during exercise simply increases the probability that circulating immune cells, such as phagocytes will come into contact with any foreign pathogens (MedlinePlus). In tandem with this, researchers were able to link rigorous training with an improvement in non-specific phagocyte related immunity (Boyum et al., 1996). This essentially means that consistent and rigorous exercise improves our bodies ability to destroy any harmful invaders. In addition to this very base mechanism, increased blood flow also stimulates lymph return via a pumping action. As a result of increased lymph return, any pathogens will come into contact with more lymphatic cells that can destroy harmful bacteria, viruses, etc. (Saladin, p. 820).

While there is a lot of evidence to show that exercise does wonders for the immune system, it is not a cure all. In her book, Christie Achwanden notes that exercise can result in an increased risk for infection (p. 202). She also notes that exercise immunologists have acknowledged that intense exercise while suffering from a more intense viral infection may increase its duration (Aschwanden, p.202). These claims likely come from the result of a temporary decrease in white blood cell count immediately after exercise. On the bright side, there is evidence that a proper active cool down after exercise can help to curb the negative acute effect (INSEP, Hausswirth, Mujika, 2013).

There is certainly value in listening to your body. If your body is telling you to rest and recover, it is likely a good idea to heed that advice. But in a vast majority, my advice would be stay fit, stay active, and stay healthy!

References

  • Aschwanden, C. (2019). Good to go. New York, New York: W.W. Norton & Company
  • Boyum, A., Wiik, P., Gustavsson, E., Beiby, O. P., Reseland, J., Hauge, A. H., & Opstad, P. K. (1996). The effect of strenuous exercise, calorie deficiency, and sleep deprivation on white blood cells, plasma immunoglobulins and cytokines. Scandinavian Journal of Immunology, 43(2), 228-235.
  • Exercise and Immunity. (n.d.) MedlinePlus. Retrieved on Apr 17, 2020 from https://medlineplus.gov/ency/article/007165.htm
  • Institut National du Sport, de l Expertise et de la Performance (INSEP), Hausswirth, C., Mujika, I. (2013). Recovery for performance in sport. Champaign, IL: Human Kinetics.
  • Saladin, K. (2010). Anatomy & Physiology: The unity of form and function. McGraw-Hill: New York, NY.