Research suggests that moderate intensity exercise improves immune function and can play a vital role in reducing the risk (and severity) of respiratory viral infections (Martin et al, 2010). Martin, and colleagues, presented a model whereby moderate exercise-induced increases in stress hormones reduced excessive local inflammation and skewed the immune response, thus improving outcomes following respiratory viral infection
"Regular exercise may reduce the risk of acute respiratory distress syndrome (ARDS), a major cause of death in patients with the COVID-19 virus" (https://news.virginia.edu/content/exercise-may-protect-against-deadly-covid-19-complication-research-suggests)
Researched performed by Dr. Zhen Yan (University of Virginia School of Medicine) has demonstrated findings that “strongly support” the possibility that exercise can prevent or (reduce the severity of) ARDS. Approximately 3% to 17% of COVID-19 patients will develop ARDS. The Centers for Disease Control (CDC) estimates roughly 20% to 42% of patients hospitalized for COVID-19 will develop ARDS. The percentage of COVID-19 patients admitted to intensive care (with ARDS) is estimated to be between 67% and 85%.
An antioxidant known as "extracellular superoxide dismutase", or EcSOD is the primary focal point of this research investigation. Skeletal muscle produces EcSOD, which assists in the destruction of harmful free radicals, and helps to prevent disease. EcSOD production is enhanced in the musculature during cardiovascular exercise. A decrease in EcSOD is evident in lung diseases (such as ARDS).
It is well known that exercise plays an important role in boosting our immune system. Professor Richard Simpson (University of Arizona) states: "Each bout of exercise, particularly whole-body dynamic cardiorespiratory exercise, instantaneously mobilizes literally billions of immune cells, especially those cell types that are capable of carrying out effector functions such as the recognition and killing of virus-infected cells" (https://www.acsm.org/blog-detail/acsm-blog/2020/03/30/exercise-immunity-covid-19-pandemic)
Professor Simpson continues to state: "Exercise also releases various proteins that can help maintain immunity, particularly muscle-derived cytokines such as IL-6, IL-7 and IL-15. The cytokine IL-6 has been shown to ‘direct’ immune cell trafficking toward areas of infection, while IL-7 can promote the production of new T-cells from the thymus and IL-15 helps to maintain the peripheral T-cell and NK-cell compartments, all of which work in concert to increase our resistance to infection. Exercise is especially beneficial for older adults who are more susceptible to infection in general and have also been identified as a particularly vulnerable population during this COVID-19 outbreak."
A host of evidence exists that demonstrates the protective effects of exercise for numerous viral infections including influenza and rhinovirus
Respiratory viral infections represent the most prevalent and pathogenic form of infectious disease (Mathers et al, 2008). research support the hypothesis that moderate exercise is protective against upper respiratory tract infection symptoms and that there may be a differential dose-response effect such that intense, prolonged exercise or overtraining increase disease risk or symptom severity. The researchers found that moderate exercise improved survival and resulted in significantly lower cell infiltration into the lungs and draining lymph nodes (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2803113/).
Based on the aforementioned data, it is my contention that moderate intensity exercise training should be used as an adjunct to other preventative measures against respiratory tract viral infections (including COVID-19).
"Moderate intensity exercise" will vary depending on an individual's age, weight, medical history, medications, disease status etc. If you would like information regarding your personal recommendations for moderate intensity exercise, please contact Dr. Peters directly (firstname.lastname@example.org).