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How Exercise Might Protect You From Severe COVID Illness

A new study out of Kaiser Permanente Southern California looks at the correlation between activity level and COVID hospitalizations and mortality.

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It has been nearly 18 months since the first reported case of COVID-19. Worldwide, over three million people have died. Americans account for over 560,000 of those deaths. But doctors and researchers are desperately working to keep that number from inching up and now have a richer data pool to understand how people can protect themselves further from serious illness and even death. 

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The CDC has cited that older adults, pregnant people, and people with other diagnosed medical conditions (such as cancer, kidney disease, diabetes, obesity, or heart disease) have an increased risk of developing severe COVID illness. But according to a new study, that grouping is missing a significant at-risk cohort, and one that has the ability to modify their risk: Inactive adults.

The study, published in the British Journal of Sports Medicine, looked at how exercise and COVID severity could be related. What the researchers found was that patients who were consistently inactive had a greater chance of being hospitalized, admitted to the ICU, or die from COVID complications than those who met physical activity minimums.  

“Even after we included variables such as obesity and smoking in the analysis, we still saw inactivity was strongly associated with much higher odds of hospitalization, ICU admission, and death compared with moderate physical activity or any activity at all,” says Dr. Robert Sallis, co-author of the study. 

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The team used electronic health records that included self-reported physical activity behaviors from nearly 50,000 patients. Since 2009, Kaiser Permanente Southern California, where the study was conducted, has included Exercise Vital Signs with every patient encounter. This allowed the research team to have access to data on how many days and how many minutes patients engaged in moderate to strenuous activity prior to the pandemic. 

Based on that information, patients were bucketed into three groupings: Consistently meeting guidelines (exercising over 150 minutes per week), some activity (exercising 11-149 minutes per week), or consistently inactive (exercising 0-10 minutes per week).

“We have known for a long time that immune function improves with regular physical activity, and those who are regularly active have a lower incidence, intensity of symptoms, and death from viral infections,” says Dr. Sallis. What was surprising about the results of the study was the strength in correlation between physical activity and response to COVID illness.  

“Regular physical activity is associated with improvements in lung capacity and cardiovascular and muscular functioning that may serve to lessen the negative impacts of COVID-19 if it is contracted,” he says. “Again, maintaining even a basic recommended level of exercise, such as walking or running 30 minutes a day, 5 days a week is enough to help your body to fight off a variety of disease, including COVID-19.” 

While there has been a steady stream of public health messaging about wearing masks, social distancing, washing hands, getting vaccinated (which are all still absolutely vital), Dr. Sallis believes the importance of exercise has been left out of the conversation. We are hopeful that the message that a little exercise can go a long way will be heard and acted upon,” he says. 

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He reiterates that in terms of exercise and COVID, the type—be it running, biking, brisk walking, hiking, weight lifting—is not as important a factor as the amount of time spent doing it. The CDC recommends 150 minutes per week. 

Another extreme benefit of exercise that can’t be overlooked is its ability to improve mental health—another crisis of this pandemic.

“It is no longer news that a lot of people are facing collateral effects of the pandemic. What is astonishing is the scale of this phenomenon,” said Rébecca Robillard, assistant professor in the School of Psychology at University of Ottawa in a recent press conference. “In parallel to the large surge in mental health symptoms, we saw in a sample of over 5,500 Canadians that insomnia symptoms are affecting one person out of two and that sleep difficulties are directly associated with worse mental health outcomes.” 

But exercise—as long as it’s not done too close to bedtime—is a factor that can lower stress and improve your quality of sleep

“This is a strong reminder of the importance of protecting sleep to improve mental health at the population level,” said Robillard.

Quality of sleep can also play a factor in the strength of your immune system. And if exercise is what will improve your quality of sleep, that is just one more reason to make sure you are meeting the physical activity recommendations. 

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High risk factors for developing severe illness from COVID-19 are real and documented. But the risk of physical inactivity is the most modifiable of them all. And according to Dr. Sallis, it’s not too late to reap the benefits of an active lifestyle. In fact, he says, he hopes people get started right away.