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Lilly Goessling


Lilly Goessling, ACE Certified Personal Trainer, Group Fitness & Cycle Instructor

There are well-known benefits to regular exercise such as improved physical fitness and weight management. Regular exercise can improve mood, focus, and sleep. It can also lower the risk of cardiovascular disease, type 2 diabetes and metabolic syndrome, and some cancers.[1]

With the onset of COVID-19, building a strong immune system to fight off illness has become a high priority for many people. Fortunately, moderate, regular exercise can have a positive effect on the functioning of the immune system by “[improving] the immune capacity of the body and [preventing] infection.”[2]

While additional research is required to completely understand the effects of exercise on the immune system, studies demonstrate that “regular moderate-intensity physical activity improves immunosurveillance against pathogens and reduces morbidity and mortality from viral infection and respiratory illnesses.”[3]

Exercise immunology studies conducted by David Nieman, DrPH, FACSM, found each session of moderate physical activity provided positive immune changes. This research shows physical activity practiced consistently will mean fewer sick days with upper respiratory tract infections.[4] This study aligns itself with the American College of Sports Medicine (ACSM) and the Centers for Disease Control and Prevention’s (CDC) recommendation that all healthy adults 18-65 years of age should participate in moderate-intensity aerobic physical activity for a minimum of 150 minutes per week.

As exercise inflicts physical stress upon the body, the sympathetic nervous system (a branch of the autonomic nervous system responsible for the “flight or fight” response) and hypothalamus-pituitary-adrenal axis (the main physiological system that mediates the body’s stress response) are stimulated to promote energy metabolism. These systems have a significant impact on the immune system’s capacity to release the leukocytes (white blood cells) responsible for fighting infections. During the acute phase that follows moderate-intensity physical activity, the levels of leukocytes can grow, helping support the immune system.[5]

Additional Tips to Improve Your Immune System

In addition to regular exercise, eat a balanced and well-diversified diet, and drink plenty of water. Remember to sleep well, practice good hygiene (e.g., handwashing), and reduce stress to help to ensure optimal immune system function.


  1. Benefits of physical activity. Centers for Disease Control and Prevention. https://www.cdc.gov/physicalactivity/basics/pa-health/index.htm. Published November 1, 2021. Accessed January 26, 2022.
  2. Xu Z, Chen Y, Yu D, et al. The effects of exercise on COVID-19 therapeutics: A protocol for systematic review and meta-analysis. Medicine (Baltimore). 2020;99(38):e22345. doi:10.1097/MD.0000000000022345
  3. Nieman DC. Coronavirus disease-2019: A tocsin to our aging, unfit, corpulent, and immunodeficient society. J Sport Health Sci. 2020;9(4):293-301. doi:10.1016/j.jshs.2020.05.001
  4. Nieman DC. Current perspective on exercise immunology. Curr Sports Med Rep. 2003;2(5):239-242. doi:10.1249/00149619-200310000-00001
  5. Simpson RJ, Kunz H, Agha N, Graff R. Exercise and the Regulation of Immune Functions. Prog Mol Biol Transl Sci. 2015;135:355-380. doi:10.1016/bs.pmbts.2015.08.001