Exercising regularly does not affect severe COVID-19 prognosis or outcomes

Study involving more than 200 hospitalized patients in São Paulo shows physically active individuals are not fully protected against the disease.

By Maria Fernanda Ziegler  |  Agência FAPESP – Recent research suggests hospitalization for treatment of COVID-19 may be significantly lower among people who exercise regularly (read more at: agencia.fapesp.br/34841/). This appears not to apply to patients with the severe form of the disease, however.

Exercising regularly did not affect the length of hospital stay or the need for mechanical ventilation and intensive care in a study conducted in the city of São Paulo, Brazil, involving 209 severe COVID-19 patients admitted to Hospital das Clínicas (HC), the hospital complex run by the University of São Paulo’s Medical School (FM-USP), and the field hospital set up at the Ibirapuera Sport Center. The results showed that exercising regularly before hospitalization was not a decisive factor in combating the disease for these patients.

“The study serves as a warning to people who think they’re fully protected because they exercise regularly. We found no difference in prognosis or clinical outcome between more and less active patients with severe COVID-19. The benefits of physical activity exist, but apparently don’t mitigate the severe form of the disease,” Bruno Gualano, a professor at FM-USP and one of the authors of the study, told Agência FAPESP.

An article describing the findings of the study, which was supported by FAPESP, is published on the preprint platform medRxiv. The article has not yet been peer-reviewed. The study was conducted in partnership with FM-USP’s Bone Metabolism Laboratory, which is headed by Rosa Maria Rodrigues Pereira, Director of HC’s Rheumatology Service.

COVID-19 is an infectious viral disease that can progress to more severe inflammatory cases. Given that so far no drugs have been developed specifically to combat SARS-CoV-2, hospital treatment consists of addressing the various symptoms of the disease and providing respiratory support where necessary.

Physical exercise is known to protect against chronic disease, Gualano explained. It also strengthens the immune system, partially preventing some infectious respiratory diseases. “Exercise has a systemic effect. It improves the individual’s immune response and metabolic and cardiovascular conditions. These factors can protect us from various kinds of chronic diseases as well as some infectious diseases. However, when the patient’s condition becomes severe, other predictors may be more decisive for clinical outcomes,” he said.

The researchers assessed the patients’ clinical status, work- or leisure-related exercise habits, and sports activity on hospital admission via a validated questionnaire. COVID-19 was diagnosed by PCR for SARS-CoV-2 from nasopharyngeal swabs or CT scan. Other eligibility criteria included having a respiratory rate of 24 breaths per minute or higher with oxygen saturation of less than 93% on room air, and risk factors for complications such as heart disease, diabetes, systemic arterial hypertension, neoplasms, immunosuppression, pulmonary tuberculosis, and obesity.

The study showed that for severe COVID-19 the presence of risk factors such as obesity, diabetes, cardiovascular disease, and old age influenced the prognosis more than exercising regularly before falling ill. No correlation was found between physical activity scores and key primary or secondary clinical outcomes such as length of hospital stay, mechanical ventilation, intensive care, and death.

Complementary studies

According to Gualano, the study complements previous research involving patients with mild and moderate as well as severe COVID-19. In a recently published study based on an online survey of 938 Brazilians who contracted COVID-19, the prevalence of hospitalization for treatment of the disease was 34.3% lower among volunteers considered “sufficiently active” before the pandemic because they had at least 150 minutes of moderately intense aerobic exercise or 75 minutes of high-intensity training per week.  

“This latest study of ours complements previous research,” he said. “The studies done before ours focus on more moderate cases of the disease, with only a small proportion of the patients requiring hospitalization.”

As well as being complementary, he added, the two studies contribute to a better understanding of the disease and of the protective effect of exercise. “It’s all very new, and few studies have so far correlated COVID-19 with physical activity and the immune system. Looking back at what we’ve published on the subject, I can say that exercise is a good predictor up to a certain stage of the disease and can help predict complications, but that isn’t true of the most critical cases. It’s important not to rely too much on the patient’s history of physical activity as an absolute protection against COVID-19,” Gualano said.

The study was funded by FAPESP via several projects (15/26937-4, 19/18039-7, 19/24782-4, 20/11102-2, 16/00006-7, 20/05752-4 and 17/13552-2). 

Risk factors for professional athletes

The FM-USP researchers are participating in a study on immune response and COVID-19 prognosis in professional athletes, conducted by Esporte-COVID-19, a consortium of researchers at HC, Hospital Israelita Albert Einstein (HIAE), the Federal University of São Paulo (UNIFESP), the Dante Pazzanese Institute of Cardiology and the São Paulo Center for High Performance in Sport (NARSP) with the support of the São Paulo State Soccer Federation (FPF).

“We want to understand the possible complications of COVID-19 in professional athletes,” Gualano said. “These can include heart damage or signs of inflammation in the heart, according to a US study of 26 college athletes. The data is new and we don’t know exactly what it means for a high-performance competitor.”

Soccer tournaments have been held during the pandemic in Brazil. Many players have been infected and have been quarantined for 10 days or two weeks, resuming participation after this period of isolation. Most have had mild or no symptoms.

“There’s no question that these high-performance athletes tend not to progress to the severe form of the disease because of their physiological conditions, but we want to find out whether they all recover fully from COVID-19 without complications,” Gualano said.

In the study, the researchers will assess 75 soccer players. Some have never caught the virus, and only some of those who did contract the disease had symptoms. “They’ll be submitted to a rigorous battery of cardiovascular tests, including an echocardiogram, an exercise stress test, an endothelial function assessment, and a cardiac MRI scan, to investigate the possibility of persistent damage,” he explained. “It’s a new disease, and we don’t yet know too much about the long-term complications, such as whether there’s an augmented risk of cardiac arrest, for example. This investigation can help us design a science-based protocol for a ‘post-COVID’ resumption of sporting activity.”

Another important aspect of the project is the possibility that it will also discover mechanisms of the disease in the general population. “These athletes are young and healthy. They have a carefully balanced diet and are very fit. They could serve as an ideal control group for any kind of comparative research. Understanding how they respond to COVID-19 could offer important physiological clues to the best ways to prevent severe cases of the disease and how lifestyles influence both its symptoms and its complications,” Gualano said.

The article “No associations between physical activity and clinical outcomes among hospitalized patients with severe COVID-19” can be read at: www.medrxiv.org/content/10.1101/2020.11.25.20237925v1.