Regular exercise lowers severe COVID-19 risk, but may raise infection odds

The emergence and rapid spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) lead to a global pandemic known as the coronavirus disease (COVID-19) pandemic. Some factors associated with a high risk of severe COVID-19 are age, physical activity (PA), and sex. Several studies have linked moderate to vigorous PA (MVPA) with a lower risk of severe infection.

Study: Association of Physical Activity With SARS-CoV-2 Infection and Severe Clinical Outcomes Among Patients in South Korea. Image Credit: sun ok / Shutterstock

Background

It is important to understand the association between MVPA and SARS-CoV-2 infection. Some studies have indicated MVPA promotes SARS-CoV-2 transmission via elevated aerosol particle emission. Other studies have indicated the health benefits linked to MVPA, such as increased immunity, which could protect an individual from severe infection. Therefore, it is essential to understand the exact effect and mechanism of physical activity on the manifestation of COVID-19.

About the Study

A recent JAMA Network Open study investigated how MVPA is associated with the risk of severe COVID-19 infection. This study hypothesized that MVPA lowers the risk of severe SARS-CoV-2 infection but elevates the risk of contracting COVID-19.

Cohort data from the Korea Disease Control and Prevention Agency (KDCA) and the Korean National Health Insurance Service (NHIS) were used to assess the change in MVPA between consecutive biennial health screenings with COVID-19 and severe SARS-CoV-2 infection. NHIS covers almost 97% of the Korean population.

The study cohort included adults who were aged 19 years or older and participated in biennial health screenings from 2017-2018 (period 1) to 2019-2020 (period 2). A total of 2,110,268 patients fulfilled all eligibility criteria and were included in this study.

Data on the leisure time PA was collected using self-reported questionnaires during biennial health screenings. Based on the responses, PA intensity was grouped into two categories, i.e., moderate PA and vigorous PA. Moderate PA was associated with exercises that cause mild shortness of breath, such as doubles tennis and fast cycling, whereas vigorous PA was those that cause severe shortness of breath, such as hiking and running. The authors calculated the metabolic equivalent task (MET) score of each participant.

The association between MVPA and COVID-19 outcomes was determined primarily based on positive SARS-CoV-2 infection. The secondary outcomes that were assessed in this study were acute clinical events of COVID-19 after hospitalization, such as the requirement of a high-flow nasal cannula (HFNC), oxygen supply with conventional oxygen therapy (COT), admission to the intensive care unit (ICU), continuous positive airway pressure, extracorporeal membrane oxygenation, and mechanical ventilation.

Study Findings

In the study cohort, a total of 183,350 patients were identified to contract SARS-CoV-2 infection. The average age of these patients was 51.9 years, 51.3% were men, and 48.7% were women. The current study revealed that MVPA was positively associated with contracting COVID-19 and negatively with severe COVID-19 outcomes.

Based on MVPA frequency in period 2, the percentage of individuals who were physically inactive and contracted COVID-19 was 35.8%, and 35.9% of individuals were not affected by the disease. Similar percentages of COVID-19 incidence and non-COVID-19 manifestations were observed among the participants whose MVPA frequencies were 1 to 2 times, 3 to 4 times, and 5 or more times per week.

The effect of MVPA levels remained the same between patients with and without SARS-CoV-2 infection between the two study periods. Nevertheless, COVID-19 vaccination status affected the disease state of the participants.

Unvaccinated persons were found to be more susceptible to infection with increased MVPA frequency at period 2 compared to physically inactive patients. An elevated MVPA also revealed a nonlinear association with COVID-19. At period 1, the infection rate increased with the elevation in MVPA frequencies among physically active/unvaccinated persons. There was no significant association between increased MVPA and patients who were reinfected with COVID-19. Decreased odd ratios (ORs) were found at period 2 with increased MVPA frequency.

A reduction in MVPA frequency revealed a nonlinear association with COVID-19 incidence. At period 2, the odds for COT and HFNC among unvaccinated patients lowered with increased MVPA frequency. In addition, the ICU admission rates were found to be insignificant in highly active participants. The risk of COVID-19 infection decreased with the completion of the primary series of COVID-19 vaccination, irrespective of MVPA frequencies. Although COVID-19 vaccination reversed the risk of HFNV, COT, and mechanical ventilation, it did not decrease ICU admission and extracorporeal membrane oxygenation.

Conclusions

The authors claim this study to be the first to investigate the longitudinal changes in MVPA with COVID-19 outcomes, considering the vaccination status of the participants. This study provided evidence that indicated MVPA increases the risk of COVID-19 but lowers the disease severity. However, the primary outcomes were reversed with COVID-19 immunization.

Written by

Dr. Priyom Bose

Priyom holds a Ph.D. in Plant Biology and Biotechnology from the University of Madras, India. She is an active researcher and an experienced science writer. Priyom has also co-authored several original research articles that have been published in reputed peer-reviewed journals. She is also an avid reader and an amateur photographer.