During the pandemic, the U.S. has been rolling out massive campaigns to reduce the transmission of COVID-19. Americans have seen countless public service announcements about wearing masks and staying socially distanced. Now that vaccines are available, there is a galvanization of research institutions, advertising agencies, and even former Presidents creating campaigns with the hope of persuading Americans to get vaccinated.
However, one critical piece of Covid-19 prevention information has not been publically heralded. Education about the benefits of exercise and advice to maintain or increase physical activity during the pandemic has been largely absent. A study published in the British Journal of Sports Medicine
exposes this lack of critical knowledge and how reduced physical activity is now considered a significant risk factor for severe COVID-19. In this article, we reveal the price of physical inactivity during the pandemic and how exercise can clinically combat the virus.
The Price of Physical Inactivity & COVID-19
The new study found that physical inactivity is not only linked to more severe COVID-19 infection but a heightened risk of dying from the virus. The research revealed that patients with the virus who were consistently inactive during the two years preceding the pandemic were more likely to go to the hospital, require intensive care, and die than patients who had regularly met physical activity guidelines. As a risk factor for severe disease, physical inactivity was surpassed only by advanced age and a history of organ transplant.
Several risk factors for severe COVID-19 infection have been identified, including advanced age, male sex, and certain underlying medical conditions, such as cardiovascular disease. However, physical inactivity is not one of them. To explore its potential impact on the severity of COVID-19 infection, the researchers compared these outcomes in over 48,000 adults with confirmed COVID-19 infection between January and October 2020.
- The participants studied had the following factors:
- The average age of patients was 47, mostly women.
- Their average weight/BMI was 31, classified as obese.
- Around half of the patients had no underlying conditions, nearly 18 percent had only one, and almost a third had two or more.
- All participants reported their level of regular physical activity at least three times between March 2018 and March 2020 at outpatient clinics. The activity was categorized as consistently inactive, some activity, or consistently meeting physical activity guidelines (150+ mins/week).
- Seven percent consistently met physical activity guidelines, 15 percent were consistently inactive, and the remainder reported some activity.
The results found that around 9 percent of the total participants were admitted to the hospital, around 3 percent required intensive care, and 2 percent died. Consistently meeting physical activity guidelines was strongly associated with a reduced risk of severe COVID-19 outcomes. Patients with the virus who were physically inactive were more than twice as likely to be admitted to the hospital as those who engaged in 150+ minutes of physical activity every week. The study also found that these same patients were:
- Twenty percent more likely to be admitted to the hospital.
- Seventy-three percent more likely to go to the ICU and more than two times more likely to die of the infection.
- Ten percent more likely to require intensive care.
- Thirty-two percent more likely to die of their infection than patients who regularly did some form of physical activity.
Now that we know physical inactivity is a risk factor in COVID-19 outcomes – the next question becomes, “How does exercise combat this deadly virus?” It begins with a small enzyme – the ACE2 receptor.
The ACE2 Factor
ACE2 (angiotensin-converting enzyme-2)
is present in many tissues, including the kidneys, blood vessels, and lungs. This enzyme is a vital factor in a network called the renin-angiotensin-aldosterone system (RAAS). RAAS plays a role in orchestrating two major pathways:
- Widening blood vessels, lowering blood pressure, anti-inflammation, and protective actions in the lung, kidney, and heart tissues.
- Narrowing blood vessels, increasing blood pressure, and tissue inflammation.
ACE2 converts Ang-II to Ang-(1-7)
, which acts on the Mas receptor. This action controls blood pressure and tissue inflammation. These actions directly oppose those induced by ACE-Ang-II signaling, where ACE converts Ang-I into Ang-II, acting at the AT1 receptor. This action increases blood pressure, promoting inflammation. This dysregulation can result in issues such as high blood pressure and heart disease. Unfortunately, ACE2 is also a receptor for the SARS-CoV-2 (virus that causes COVID) spike protein, where the virus gains entry to host cells. The binding of the virus to the ACE2 site downregulates the receptor axis. With less ACE2 available to convert Ang-II to Ang-(1-7), Ang-II signaling speeds up. Without the ability for ACE2 to put the brakes on Ang-II, injury and inflammation to tissues occur in Covid-19 patients. After SARS-CoV-2 binds to the ACE2 receptor, the virus subverts the immune system and multiplies.
Out of the many proteins created by SARS-CoV-2, the nucleocapsid protein, or N-protein, is one of the virus’s secret weapons. The N-protein blocks interferon (IFN) production, which is critical to preventing cell replication. This feature allows the virus to suppress the host’s initial innate immune response – enabling it to reproduce without being noticed by the body. During this action, the virus activates the cytokine storm – causing massive inflammation throughout the body. Now that we know the journey COVID-19 takes, it is time to understand how physical activity clinically helps battle the virus.
How Exercise Combats COVID-19
A review article in Frontiers in Physiology reports that exercise increases ACE2, and we know that ACE2 via Ang-(1-7) has anti-inflammatory effects. This action inhibits Ang-II, reducing cytokine release and hindering the signaling of tissue fibrosis pathways. The report states that by increasing ACE2, exercise may help reduce scarring to the lungs and prevent respiratory issues like Acute Respiratory Distress Syndrome (ARDS). We also know that SARS-CoV-2 produces proteins that block interferon production. This action suppresses the host’s immune response – allowing it to replicate undetected. However, research shows that physical activity may have a targeted impact on interferon and cytokine responses in the bloodstream. One study revealed that post-exercise cell cultures showed a significant increase of interferon and IL-12 compared to their pre-exercise samples.
Regular exercise may also help reduce the severity of ARDS for those with COVID-19 with help from Extracellular Superoxide Dismutase (EcSOD), a potent antioxidant released during physical activity. A review by Zhen Yan revealed that aerobic and strength training improves muscle action, causing a rise in EcSOD. This antioxidant protects the lung and kidney tissue and reduces inflammation. The review suggests that even a single session of exercise boosts the production of the antioxidant.
Research also shows that fighting senescent cells can help strengthen the immune system and decrease inflammation. Senescent cells secrete a mix of signals that spur chronic inflammation, destroy tissues, and encourage nearby cells to become senescent. Exercise, especially muscle strengthening, can help clear out these cells, making way for healthy new ones. It does this by supporting immune balance through bone marrow homing and increasing the death of senescent T-cells. This action stimulates the production and release of new cells.
The researchers of the latest British Journal of Sports Medicine study conclude, “We recommend that public health authorities inform all populations that short of vaccination and following public health safety guidelines such as social distancing and mask use, engaging in regular physical activity may be the single most important action individuals can take to prevent severe COVID-19 and its complications, including death.”
