We now know that nutrition plays an important role in keeping ourselves healthy, but what about exercise? And how much exercise should we be doing? These questions have a lot of controversy around them and much more research is needed to draw complete conclusions, but for now this is what we know. The relationship between exercise and a healthy immune system can be considered a bell curve; too little exercise and your immune system suffers, but too much exercise and your immune system also suffers. The ideal amount is right in the middle. Most research supports this middle ground as being regular sessions of short, around 45 minutes, moderate intensity exercise. (1) Too little exercise, or sedentary behavior, promotes many negative states in your body, including energy imbalances (more calories in then burned), higher blood sugar, higher blood pressure and a pro-inflammatory status. While all these things have consequences on your overall health, a pro-inflammatory status is the major concern with your immune system. This means that if you did come into contact with a pathogen your body is going to promote inflammation for longer, leading to a longer and high fever.2 Whereas when there is a more anti-inflammatory status your immune cells will kill the pathogen and decrease the fever quicker. (2) Too much exercise can be considered the amount that an elite high-performance athlete completes, like a D1 athlete or a professional in any sport. These athletes complete exercise at a high intensity for long periods of time and this can lead to an altered immune response. Research has shown that cellular markers of immunity are altered for several hours to day post strenuous exercise, and during this time the athlete is at a higher risk for developing an illness if a pathogen is present. (1) Moderate exercise bouts are the best of both worlds between these two states. During exercise there is an exchange of immune cells between the blood and the tissues. With too little exercise this exchange rarely happens, and with too much exercise this exchange happens too often. But with moderate exercise this exchange occurs at the correct ratio to enhance the function of immune cells allowing them to find and kill pathogens more efficiently. (1) This leads to an overall lower risk of illness. There is still more research that needs to be done on this topic, but one thing that all researchers agree on is that exercise is necessary to keep your body in a positive state to help prevent against illness. While there are other things to consider in regard to immunity, like stress, sleep, nutrition, infection history, and vaccination, exercise, when used correctly, can greatly impact how your body responds to a pathogen to keep you as healthy as can be.
1. Simpson RJ, Campbell JP, Gleeson M, et al. Can exercise affect immune function to increase susceptibility to infection? Exerc Immunol Rev. 2020;26(8):8-22. https://www.ncbi.nlm.nih.gov/pubmed/32139352
2. Fernandez DM, Clemente JC, Giannarelli C. Physical Activity, Immune System, and the Microbiome in Cardiovascular Disease. Front Physiol. 2018;9. doi:10.3389/fphys.2018.00763