Walk down Main Street, USA, and you will get as many opinions about exercise as there are ice cream flavors at Baskin-Robbins. Whether or not you agree with your neighbor, one truth stands out. A lack of exercise increases the risk of degenerative disease (i.e., heart disease, diabetes, dementia, etc.). Despite the arduous work of health and fitness professionals, most Americans don't embrace this reality! However, interest in exercise is growing due to groundbreaking research. Scientists now understand how exercise strengthens your immune system to lower your risk of infectious diseases (viral, bacterial, etc.).
Last year, the World Health Organization updated its Physical Activity Guidelines.[1] The guidelines represent a significant step forward in public health. However, a member of the expert panel that helped formulate the guidelines identified a gap in the research. According to Dr. Sebastian Chastin, a Professor of Health Behavior Dynamics in the School of Health and Life Sciences at Glasgow Caledonian University, the new guidelines did not address the relationship between exercise and infectious disease. In other words, they only looked at the connection between degenerative diseases and exercise (i.e., cardiovascular disease, stroke, cancer, diabetes, osteoarthritis, osteoporosis, dementia). Dr. Chastin, known for his prolific contributions to exercise research, organized his team and began synthesizing a review of research on the relationship between exercise and infectious diseases.
Earlier this year, Dr. Chastin's team published groundbreaking research demonstrating exercise's power to fight off infections by enhancing the immune system. The study revealed three critical insights about infectious disease transmission. First, exercise strengthens the immune system's outer layer, preventing viruses from entering the body. Most infections begin in the mucosal surfaces, including the mouth, eyes, and nose. Specific antibodies protect these surfaces, which provide a barrier that prevents viruses from entering the body. Exercise increases IgA antibodies (immunoglobulin, type A) in mucosal surfaces, effectively reducing infection rates.[2]
Second, the immune system changes in response to exercise, specifically CD4 T-cells. These surveillance cells that alert the immune system that something may be wrong increase in response to exercise. They also orchestrate the immune response, influencing how our bodies respond to an infectious assault. This enhanced immune system response lowers mortality rates among infected exercisers.[3]
Third, if you are an exerciser, your body will respond more strongly to vaccinations, which makes vaccines more effective. These findings are relevant to the current and future immunization schedules (i.e., influenza, HPV, etc.). The amount of exercise necessary to stimulate these positive changes is consistent with the current World Health Organization Guidelines on Physical Activity (approximately 30 minutes of moderate to vigorous daily exercise). Regular exercise can improve your primary barrier, preventing viruses from entering the body; if a virus does, the cells that orchestrate the immune response increase in number and functional ability, effectively lowering mortality rates. Lastly, vaccinations are more effective in exercisers.[3],[4]
As new viruses develop and existing viruses replicate, there has never been a better time to strengthen your immune system! Fortunately, your immune system can mount a more robust defense against viral and bacterial infections if you exercise. Based on the current World Health Organization Guidelines on Physical Activity, structured exercise (i.e., supervised Strength Training) and unstructured activity (i.e., walking, biking, hiking, etc.) strengthen your immune system. If you are not living the Strength Training Lifestyle, you limit your immune system's ability to protect your body against harmful infections.
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Stay Strong,
Richard J. Wolff, RDN
References
1. World Health Organization 2020 Guidelines on Physical Activity and Sedentary Behavior. https://bjsm.bmj.com/content/54/24/1451
2. Effects of Regular Physical Activity on the Immune System, Vaccination and Risk of Community-Acquired Infectious Disease in the General Population. https://doi.org/10.1007/s40279-021-01466-1
3. Effects of Regular Physical Activity on the Immune System, Vaccination and Risk of Community-Acquired Infectious Disease in the General Population. https://doi.org/10.1007/s40279-021-01466-1
4. Joint association between accelerometry-measured daily in a combination of time spent in physical activity, sedentary behavior, and sleep and all-cause mortality; a pooled analysis on six prospective cohorts using compositional analysis. https://bjsm.bmj.com/content/early/2021/05/09/bjsports-2020-102345.full