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Clinical Context

Regular physical activity has many health benefits, including protection against respiratory infection severity and reducing risk factors for adverse COVID-19 outcomes, such as obesity, cardiovascular disease, and type 2 diabetes.

During the COVID-19 pandemic, physical activity appears to enhance immune defense and mitigate harmful effects of stress on immunity. The link between regular physical activity and COVID-19 outcomes is poorly understood but likely involves both metabolic and environmental factors. New research suggests that regular physical activity can help lower the risk for COVID-19 and its severity.

Study Synopsis and Perspective

According to a new study, a weekly tally of 150 minutes of moderate or 75 minutes of vigorous physical activity may afford the best protection against adverse COVID-19 outcomes.

"Our findings highlight the protective effects of engaging in sufficient physical activity as a public health strategy, with potential benefits to reduce the risk of severe COVID-19," said Antonio García-Hermoso, PhD, Public University of Navarra, Pamplona, Spain, and colleagues.

"Regular physical activity seemed to be related to a lower risk of COVID-19 infection, García-Hermosa told Medscape Medical News. "There is evidence that regular physical activity might contribute to a more effective immune response, providing enhanced protective immunity to infections, which could explain the relationship between exercise consistency with COVID-19 infection."

Regular exercise may also help to boost the body's anti-inflammatory responses, as well as cardiorespiratory and muscular fitness, all of which may explain its beneficial effects on COVID-19 severity, the researchers said.

The study was published August 22 in the British Journal of Sports Medicine.

A growing body of evidence suggests that increased physical activity may modulate the course of COVID-19 and reduce the risk for poor outcomes. The new analysis is the first to systematically evaluate and pool data on the effect of regular physical activity on COVID-19 outcomes.

The findings are based on data from 16 studies with more than 1.8 million adults (53% women; mean age 53 years).

Individuals who included regular physical activity in their weekly routine had an 11% lower risk for infection with SARS-CoV-2 (HR 0.89 [95% CI: 0.84, 0.95]) compared with inactive peers.

The physically active adults also had a 36% (HR 0.64 [95% CI: 0.54, 0.76]) lower risk of being hospitalized, a 44% (HR 0.66 [95% CI: 0.58, 0.77]) lower risk for severe COVID-19 illness, and a 43% (HR 0.57 [95% CI: 0.46, 0.71]) lower risk of dying from COVID-19 than their inactive peers.

The greatest protective effect occurs with achieving at least 500 metabolic equivalent of task (MET) minutes per week of physical activity -- equivalent to 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity physical activity per week with no added benefit beyond this level.

The researchers cautioned that the analysis included observational studies, differing study designs, subjective assessments of physical activity levels, and concerned only the Beta and Delta variants of SARS-CoV-2, not Omicron.

Despite these limitations, the researchers said their findings "may help guide physicians and healthcare policymakers in making recommendations and developing guidelines with respect to the degree of physical activity that can help reduce the risk of infectivity, hospitalization, severity, and mortality of COVID-19 at both the individual and the population level, especially in high-risk patients."

Reached for comment, Sean Heffron, MD, a preventive cardiologist and assistant professor of medicine at New York University (NYU) Langone Health in New York, New York, said the study "supports the well-established nonlinear association of increasing physical activity with adverse outcomes from a diverse array of diseases, including infectious diseases, such as COVID-19."

The observation is not particularly surprising, he told Medscape Medical News. 

"It is as I would suspect. They compiled data from a large number of studies published over the past several years that all had consistent findings," Heffron said.

"The take-away from a public health standpoint is that being physically active improves health in myriad ways. That being said, it is not a panacea, so additional measures (masking, vaccinations, etc.) are important for everyone," he said.

Also weighing in, Joseph Herrera, DO, chair of the department of rehabilitation for Mount Sinai Health System in New York, New York, said, "If you are physically fit, your body is more resilient and better prepared to handle the stressors of COVID or any other disease process."

For now, however, the question of whether physical fitness is actually protective against COVID-19 remains unclear.

"I'm just not sure right now," Herrera told Medscape Medical News.

He said he has treated athletes in professional sports, including the National Football League and Major League Baseball, and some of them have had long COVID-19 and have not returned to play.

"These are athletes at the peak of fitness and their career," he added.

Nonetheless, Herrera said a good public health message in general is to stay fit or get fit.

"That's something I preach all the time," he told Medscape Medical News.

García-Hermosa agreed: "In contrast to the vast majority of drugs, exercise is free of adverse effects. It's time to consider exercise as medicine. It's never too late to start being physically active."

The study had no specific funding. García-Hermoso, Heffron, and Herrera have reported no relevant financial relationships.

Br J Sports Med. Published online August 22, 2022.^[1]

Clinical Implications

• Regular physical activity seemed to be related to lower likelihood for adverse COVID-19 outcomes.
• The findings may inform guidelines regarding the extent of physical activity that can help lower risk for adverse COVID-19 outcomes.
• Implications for the Healthcare Team: While potentially helpful, sufficient exercise alone does not protect against COVID-19. The healthcare team should continue to educate patients on the need for additional preventive measures, such as masking and vaccinations.

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