Exercise shown to reduce COVID infection, severity and mortality

Exercise as medicine: the countless benefits of regular physical activity include brain health, heart health, mental health, bone health, immune system strength, as well as it being a key lifestyle factor for preventing chronic disease.
 
But since the COVID-19 pandemic began, emerging evidence has led to those benefits being expanded further still, with exercise now recognised as playing a role in reducing the risk of infection and disease severity, including hospital admission and death.
 
The latest findings, published in the British Journal of Sports Medicine (BJSM), stem from an analysis of three major research databases of the most up-to-date evidence on relevant studies.
 
From the research, 16 studies were used involving a total of more than 1.8 million adults across several countries, of which 54% were women, with an average age of 53 years for all participants.
 
Those who engaged in regular physical activity were found to have a lower risk of infection (11%), hospitalisation (36%), severe COVID-19 illness (44%) and COVID-related death (43%) compared with the inactive cohorts.
 
An average weekly tally of 150 minutes of ‘moderate intensity’, or 75 minutes of ‘vigorous intensity’ physical activity offers optimum protection, according to the authors.
 
‘Regular physical activity seems to be related to a lower likelihood of adverse COVID-19 outcomes,’ the authors write.
 
‘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.
 
‘Regular physical activity is associated with a multitude of beneficial health effects, including the reduction of the incidence of risk factors for adverse COVID-19 outcomes, ie obesity [and] type 2 diabetes.’
 
Noting the role of vaccination and antiviral treatments in reducing severity and mortality of COVID-19, the authors state their results also support findings of several other studies linking physical activity with infectious diseases.
 
A systematic review and meta-analysis published in 2021 tracked the effects of regular physical activity on the immune system, vaccination effect and risk of community-acquired infectious diseases. It showed that regularly engaging in moderate-to-vigorous exercise is associated with 31% lower prospective risk of infectious disease and 37% lower risk of infectious disease-related mortality. 
 
Further studies suggest physically active people have less severe symptoms of COVID-19, shorter recovery times and may be less likely to infect others they come into contact with.
 
Alongside their findings, the BJSM authors also cite previous studies demonstrating the link between physical activity and ‘improved immune markers in several diseases’ related to COVID-19, including obesity, cardiovascular disease and diabetes, which they state are ‘known predictors’ of severe COVID-illness and mortality.
 
While the authors acknowledge that the link between regular physical activity and COVID-19 severity involves metabolic and environmental factors, they say more research is needed ‘to quantify the threshold of physical activity that might be needed to lessen the risks of infection and associated hospital admission and death’.
 
They also note several limitations of the studies mean that the findings ‘may be weakened’ and should be ‘interpreted with caution’.
 
Limitations include the pooled analyses had differing study designs, subjective assessments of physical activity levels, and the fact that the majority of participants included in the 16 studies were mainly exposed to the Beta and Delta variants of SARS-CoV-2, before the Omicron variant became globally dominant.
 
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