TORONTO -- A study out of California has determined that physical inactivity is associated with higher risk of severe COVID-19 outcomes.

The study, run out of the Kaiser Permanente Medical Center in California, examined 48,440 adult patients who were diagnosed with COVID-19 from January to October in 2020. Researchers then compared hospitalization rates, intensive care unit (ICU) admissions and mortality rate for patients who were consistently inactive, doing some activity, or consistently meeting physical activity guidelines.

The study cites the U.S. Centers for Disease Control’s (CDC) risk factors for severe COVID-19 outcomes, including advanced age and comorbidities, such as diabetes, obesity and cardiovascular disease – but said there was “no data” regarding the effect of regular physical activity on COVID-19 outcomes - even though a lack of physical activity is a “well-documented” underlying risk factor for multiple chronic diseases, including those associated with severe COVID-19.

The study said it is “reasonable to expect” that regular physical activity may mitigate poor COVID-19 outcomes, citing improved immune function, reduction of systemic inflammation, benefits to cardiovascular health and mental health – but that lockdowns and stay-at-home orders have restricted access to venues where people can be active.

Researchers used an electronic health record (EHR) that captured self-reported physical activity behaviours prior to the pandemic in order to test the theory that consistently meeting activity thresholds prior to diagnosis was associated with less severe COVID-19 outcomes.

Study participants were enrolled at the Kaiser Permanent Center for at least six months before their COVID-19 diagnosis, and were required to have had at least three outpatient visits between March 2018 and March 2020 in which a nurse or assistant would ask about and record their typical exercise habits. This was done to ensure the EHR captured accurate physical activity habits, the study said.

Among all of the COVID-19 patients studied, researchers recorded that 8.6 per cent of them were hospitalized, with 2.4 per cent of those admitted to the ICU and 1.6 per cent died.

Those who were consistently meeting physical activity guidelines were less likely to be hospitalized, admitted to the ICU, or die in relation to COVID-19 compared to those who were consistently inactive or only doing some activity.

Researchers say this is the first study that demonstrates that physical activity is an important and modifiable risk factor for severe COVID-19 outcomes.

Other than advanced age and a history of organ transplant, physical activity was the strongest risk factor for severe COVID-19 outcomes in the patients studied.

“The magnitude of risk for all outcomes associated with being consistently inactive exceeded the odds of smoking and virtually all of the chronic diseases studied in this analysis, indicating physical inactivity may place a crucial role as a risk factor for severe COVID-19 outcomes,” the study states.

Researchers said the potential for regular physical activity to lower COVID-19 illness severity should be promoted by public health agencies and that pandemic control recommendations should include regular physical activity across all population groups.