Hospitalization for treatment of COVID-19 is 34% lower among physically active people, study shows

The online survey was conducted in Brazil and completed by 938 survivors of the disease whose diagnosis was confirmed by RT-PCR or serological test. Those who regularly had at least 150 minutes per week of moderately intense aerobic exercise or 75 minutes of high-intensity training were considered sufficiently active, in accordance with the WHO’s recommendations.

By Karina Toledo  |  Agência FAPESP – Results of an online survey covering 938 Brazilians who contracted COVID-19 show that the prevalence of hospitalization for treatment of the disease was 34.3% lower among volunteers considered “sufficiently active” before the pandemic because they performed at least 150 minutes of moderately intense aerobic exercise or 75 minutes of high-intensity training per week. 

The questionnaire was completed between June and August by individuals of both genders and varying ages who had had infection by SARS-CoV-2 confirmed by molecular test (RT-PCR, which detects the virus’s RNA in the acute stage) or serological test (which detects antibodies to the virus in the blood). Only 91 participants, or 9.7%, needed hospitalization. A full report of the study, which was supported by FAPESP, is published on the medRxiv platform in an article that has not yet been peer-reviewed.

The researchers based their definition of “sufficiently active” on the recommendations of the World Health Organization (WHO) for adults aged 18-64. These are based in turn on the guidelines of the world’s leading medical bodies. 

“We also looked to see if hospitalization prevalence was lower for people who practiced less than the recommended amount of weekly exercise, but in this case the difference was not statistically significant,” Marcelo Rodrigues dos Santos, postdoctoral fellow at the University of São Paulo’s Medical School (FM-USP) and last author of the article, told Agência FAPESP.

The survey asked questions about clinical items (symptoms, medications, length of hospital stay, if any) and other factors that influence the outcome of infection, such as age, gender, body mass index (BMI), pre-existing medical conditions, financial situation, educational attainment, tobacco use, and amount of regular physical exercise.

The completed questionnaires were analyzed by statistical models and, as expected, hospitalization prevalence was higher among men, the elderly (65 and over), the overweight and obese, and the relatively poor and undereducated. However, even after the influence of these risk factors on the results was discounted, hospitalization prevalence was 34.3% lower for the “sufficiently active” group. 

A comparison with respondents who required hospitalization showed that the level of physical activity before the pandemic did not confer protection in terms of length of hospital stay, intensity of symptoms, and the need for oxygen therapy or intubation.

“The study was observational, so we didn’t investigate the mechanisms involved in the protection conferred by physical activity, but there is robust evidence of the benefits of exercise for immunity. A single session can mobilize billions of defense cells, reintroducing them into the bloodstream,” Santos said.

As the authors note in the article, physical activity helps control weight and prevent chronic diseases such as diabetes and high blood pressure, considered risk factors for severe COVID-19.

In parallel

When COVID-19 reached the Americas, Santos had just moved to Boston in the United States, where he was due to start a research internship at Harvard University with FAPESP’s support. 

The aim of the project is to try to reverse the effects of aging and degenerative disease by means of interventions capable of restoring cellular levels of NAD (nicotinamide adenine dinucleotide), a coenzyme that participates in several important biological processes. Research shows that levels of NAD fall with aging and that this decline is associated with the development of metabolic disorders such as obesity.

“The proposal is to test in obese or overweight patients the effect of a novel supplement suspected of boosting the action of NAD, but when the number of COVID-19 cases exploded everything was shut down. The investigation was temporarily interrupted, and we decided to do an online survey in parallel,” Santos explained.

Santos networked with colleagues in physical education in several Brazilian states to help disseminate the link to the questionnaire via hospitals, clinics, newspapers, and social media. Researchers at the Federal University of Minas Gerais (UFMG), Hospital de Clínicas in Porto Alegre (Rio Grande do Sul State), the Federal University of Rio Grande do Sul (UFRGS), Rio de Janeiro State University (UERJ), and the University of São Paulo’s School of Physical Education and Sports took part in the initiative.

“It was a sort of multicentric study carried out online,” Santos said.

The article “Physical activity decreases the prevalence of COVID-19 associated hospitalization: Brazil EXTRA study” can be read at: www.medrxiv.org/content/10.1101/2020.10.14.20212704v1.full.pdf.