There are many reasons to stay physically active. Most people exercise to improve their body composition, lose weight, and reduce their risk of health problems such as cardiovascular disease. But there’s another benefit of regular staying physically active. A new study finds exercise may lower the risk of developing severe COVID-19.
There isn’t a surefire way of knowing who will develop severe COVID-19 symptoms, however, age and certain medical problems increase the risk. Research also shows that obesity raises the risk of COVID complications, possibly by boosting inflammation. One way to lower the risk of obesity is to exercise, but does physical activity lower the odds of severe COVID-19 independent of body weight?
COVID-19, Exercise, and Inflammation
It makes sense that moderate physical activity might reduce the risk of complications related to the virus since studies show exercise has an anti-inflammatory response. The complications of COVID mainly come from the body’s reaction to the COVID virus and the ensuring inflammatory response. So, anything that subdues the inflammatory response would likely be of benefit for preventing severe COVID-19.
What about exercise? In a study that ran from January to October 2020, researchers followed the health outcomes of 48,400 adults of various ethnicities who tested positive for COVID-19. The average age of the subjects was 47 and two-thirds were female. At least half of the people had no health problems that placed them at higher risk, although many were obese.
After questioning the participants about their physical activity on three occasions spanning several years, they divided the subjects into groups based on how active they were. Only 7% of the participants met the mandated guidelines for physical activity. (150 minutes of moderate-intensity exercise per week.) Around one of six were not physically active, while the others got varying degrees of exercise ranging from minimal physical activity to almost meeting the guidelines.
What were their outcomes? Almost 9% of the subjects were ill enough to require hospitalization. Three percent of the participants needed ICU care and 2% died. When the researchers compared the exercise habits of the participants with their outcomes, they found those who exercised enough to meet the mandated guidelines were less likely to be admitted to the hospital. In fact, sedentary subjects were over twice as likely to be hospitalized and had a death rate 2.5 times higher than those who met physical activity guidelines.
If you’re physically active, these results are encouraging. However, this is an associational study and doesn’t necessarily show that exercise itself reduces hospitalization rates and death. It could be some other habit that people who exercise do or some other characteristics that exercisers have in common that explain the lower hospitalization and death. The strength of the study is its large size and the fact it looked at a variety of ethnic groups.
Still, the conclusions of the study are fascinating. According to the researchers, being inactive was a more powerful risk factor for severe COVID-19 than other risk factors, including health problems like hypertension, diabetes, cancer, and cardiovascular disease. Only two risk factors were stronger than inactivity—being older and a history of an organ transplant.
You might not hear doctors recommending exercise to patients during the COVID pandemic as much as they should but maybe they should be. Exercise helps optimize immune function and may lower the risk of other viral infections too.
Balance Exercise with Adequate Rest and Recovery
No need to overdo those workouts though. According to a study presented to the Society for General Microbiology, couch potatoes catch more upper respiratory infections, or colds, than people who do moderate amounts of exercise. Research shows physical activity can lower the risk of upper respiratory infections by close to a third. However, there is a point of diminishing returns and even evidence of harm beyond a certain threshold of exercise. Doing strenuous workouts without giving your body time to rest and recover can increase the odds of developing a viral respiratory infection.
Why might this be? Intense and frequent exercise boosts the stress hormone cortisol, and this can weaken immune function and give viruses a chance to gain a foothold and cause illness. Sleep matters too. A good night’s sleep is the ultimate recovery for your body. Doing back-to-back high-intensity workouts and not compensating by getting at least 7 hours of sleep can lower your immune system.
One way exercise affects the immune system is by boosting the activity of natural killer (NK) cells. NK cells are powerful players in the fight against viruses. Moderate exercise increases their activity, so they’re more capable of fighting viral infections, while prolonged, especially intense, activity has the opposite effect. It cripples their activity, giving viruses a better chance of gaining a foothold.
The Bottom Line
A healthy lifestyle that includes exercise is one way to optimize the health of your immune system and that may lower your risk of viral infections in general. But with a serious infection like COVID-19, don’t count on exercise alone for protection.
References:
- Robert Sallis, Deborah Rohm Young, Sara Y Tartof, James F Sallis, Jeevan Sall, Qiaowu Li, Gary N Smith, Deborah A Cohen. Physical inactivity is associated with a higher risk for severe COVID-19 outcomes: a study in 48 440 adult patients. British Journal of Sports Medicine, 2021; bjsports-2021-104080 DOI: 10.1136/bjsports-2021-104080.
- Society for General Microbiology. “Couch potato or elite athlete? A happy medium keeps colds at bay.” ScienceDaily. ScienceDaily, 5 January 2012. www.sciencedaily.com/releases/2012/01/120105112158.htm
- “COVID-19 and the role of chronic inflammation in patients ….” https://pubmed.ncbi.nlm.nih.gov/32409680/.
- “New insights on inflammation in COVID-19.” 21 Apr. 2021, https://medicalxpress.com/news/2021-04-insights-inflammation-covid-.html.
- “NIH study uncovers blood vessel damage and inflammation in ….” 30 Dec. 2020, https://www.nih.gov/news-events/news-releases/nih-study-uncovers-blood-vessel-damage-inflammation-covid-19-patients-brains-no-infection.
- “Sleep and immune function – PubMed.” https://pubmed.ncbi.nlm.nih.gov/22071480/.
- “Sleep & Immunity: Can a Lack of Sleep Make You Sick ….” 19 Nov. 2020, https://www.sleepfoundation.org/physical-health/how-sleep-affects-immunity.
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