“But I need to emphasize that we are treating Covid no differently to other bugs like the flu.”Anna Meares, Chef de Mission, Australian Olympic team
“My grandmother started walking five miles a day when she was sixty. She's ninety-seven now, and we don't know where the heck she is.”
Ellen DeGeneres, American comedian, actress, and writer
Two days before the 2024 Summer Olympics’ Opening Ceremony, five players on Australia’s water polo team tested positive for COVID-19 causing CNN to report, “An unwelcome attendee has joined the Paris Olympic Games: Covid-19.” This announcement prompted a flashback to the 2020 Tokyo Olympics that were postponed for a year because of the rampaging COVID-19 pandemic.
We learned many lessons about how to safely organize mass gatherings during a pandemic due to the postponement of the Tokyo 2020 Summer Olympics—lessons applied subsequently to the Beijing 2022 Winter Olympics. (See, “The Tokyo and Beijing 2022 Olympic Games held during the COVID-19 pandemic: planning, outcomes, and lessons learnt,” Lancet, February 3, 2024). Moreover, in anticipation of this summer’s games, the World Health Organization’s “mass gathering expert group” developed and deployed guidelines to mitigate the public health risks at the 2024 Olympics.
COVID-19 did not stop this year’s games; we have all been able to witness the prowess of this summer’s Olympians. As I watched in awe as these athletes competed, my mind drifted to subjects my wife often accuses me of dwelling on—infectious diseases and the immune system. Since I last reviewed the topic of the impact of physical exertion on immunity in 2020, (See, “Exercise, Sunshine, and the Immune System,” Germ Gems, July 8, 2020), new research has added to our understanding of this topic. So, once again, the interplay between exercise, immunity, and infectious diseases is the subject of a Germ Gems post.
Relationship between physical exercise and COVID-19. By the time the 2020 Tokyo Olympics were postponed in July 2020, more than 17 million cases and almost 700,000 COVID-19-related deaths were reported globally. As of July 2024, these numbers mushroomed to over 774 million cases and more than 7 million SARS-CoV-2-related deaths. Historically, COVID-19 is the fifth most lethal pandemic, ranking right behind the Black Death (Bubonic Plague)—the subject of last week’s Germ Gems post.
Given the enormous impact of the COVID-19 pandemic on human health as well as on many facets of society, from the start of the pandemic in early 2020, the search was on for beneficial measures (treatments), both behavioral and pharmacological. For example, by 2021 physical inactivity was recognized as a risk factor for severe COVID-19 in adults, and the beneficial effects of physical exercise on SARS-CoV-2 infection were being investigated. (See “Relationship between physical exertion and COVID-19 [SARS-CoV-2]: systematic review,” Sports Sciences for Health, 2023).
Studies demonstrating that physical exercise can be a component for the treatment of COVID-19 supported the hypothesis that the mechanism for this beneficial effect is related to favorable effects on the immune system. (See “Physical exercise as a tool to help the immune system against COVID-19: an integrative review of the current literature,” Clinical and Experimental Medicine, 2021.) The postulated positive link between physical exertion and the immune system is also supported by research in mouse models carried out at Harvard Medical School.
In the April 13, 2024 Technology Network Immunology & Microbiology article “Exercise and the Immune System: What’s the latest Research?,” senior science writer Blake Forman points out that although exercise immunology is considered a relatively new area of study, its beginnings can be traced back to 1902. He also reports that recent studies suggest that the long-term benefits of exercise are relevant not only to defense against pathogens, like SARS-CoV-2 (the cause of COVID-19), but also to improving the prognosis of cancer patients.
Exercise good judgment. In the July 23, 2024 New Scientist article “What is the optimal amount of exercise and how much is too much?,” science writer Michael Marshall suggests, “The benefits of exercise are so great that if it were a drug, it would be a miracle cure.”
Marshall’s enthusiastic view may overestimate the benefits of exercise on health. Too much of a good thing, even exercise, can be detrimental to your health—a point Dr. Chayil Champion discusses in his November 17, 2023 UCLA Health article, “No pain, no gain? Training too hard can have serious health consequences.”
Marshall is quick to point out, however, that the evidence suggests you don’t have to be an elite athlete to accrue the benefits. The results of a new study support the aim for moderation in the amount of exercise. The researchers found that just 15 minutes of exercise can boost the production of natural killer (NK) cells, a type of white blood cell that fights both infectious agents and cancerous cells in the body.
Finally, it’s important to remember that the body’s immune system is connected to the nervous system (i.e., the brain), and it’s possible the health benefits of physical activity are in part related to the bidirectional interaction between the mind and the body. On this note, I confess that my heart was exercised by Celine Dion’s comeback performance of “Hymne a l’amour” at the opening ceremony of the Paris Olympics. Take a few minutes to listen to her on this YouTube link it’s guaranteed to lift your spirits and, who knows, perhaps even your immune system.
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