Exercise during the coronavirus pandemic, two sides of the same coin: the intensity-specific effect of physical training on the innate and acquired immune systems of humans

Document Type : Review


1 Department of Exercise Physiology, Faculty of Sports Sciences, University of Mazandaran, Babolsar, Mazandaran, Iran

2 Assistant Professor of Exercise Physiology, Clinical Biomechanics and Ergonomics Center, Aja University of Medical Sciences, Tehran, Iran

3 Department of Exercise physiology, Ahvaz Branch, Islamic Azad university, Ahvaz, Iran

4 Ph.D. in Sport Management, Islamic Azad University, Tehran North branch, Tehran, Iran


In recent years, the global spread of the novel coronavirus responsible for COVID-19 has posed an unprecedented public health threat. Fortunately, research has shown that regular, moderate-intensity aerobic exercise can have a positive impact on the immune system when it comes to upper respiratory tract infections (URTI). Numerous studies have demonstrated that moderate aerobic exercise at 65–80% VO2max can boost antibody production, lymphocyte proliferation, gamma interferon levels, immunoglobulin M and G levels, natural killer cell counts, and Toll-like receptor activity. This suggests that exercise is beneficial for immune function in both recreational and elite athletes, with a J-shaped curve for recreational athletes and an S-shaped curve for elite athletes. Therefore, it's important for individuals of all ages to engage in regular exercise to enhance their immune response. Some helpful recommendations may include: During this time, it's wise to avoid heavy exercise, as it could potentially increase susceptibility to infection through the open window hypothesis. However, healthy individuals who don't exhibit symptoms can still benefit from moderate exercise while following proper hygiene protocols. This aligns with the J-shaped model, which suggests that moderate exercise can enhance immune system function. If you're experiencing mild upper respiratory symptoms, such as a runny nose or sinus congestion, it's safe to engage in light exercise for no more than 60 minutes with precautions. However, it's important to limit the intensity and duration to no more than 60% VO2max in one hour. If you're exhibiting lower-neck symptoms, such as fever, cough, severe sore throat, myalgia, shortness of breath, or general fatigue, it's best to avoid exercise altogether if you suspect you may have COVID-19.


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