Sarah Chapman looks at Cochrane evidenceCochrane Reviews are systematic reviews. In systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. on whether exercise affects our susceptibility to acuteA health condition (or episodes of a health condition) that comes on quickly and is short-lived. respiratory infections.
Page originally published: 07 April 2020. Republished: 06 January 2022 with changes to the discussion of the topic’s context.
Among the rapid changes that swept in with the coronavirus (COVID-19) pandemic was a new enthusiasm for exercise. During the first lockdown, my husband, who spent much of his career working on strategies to get the nation exercising, looked on in astonishment at each person striding past our window, kitted out for a walk, and at family units yomping the footpaths through the nearby fields. Many of us supplemented our daily allowance of outdoor exercise with indoor sessions stretching and jumping in front of YouTube, ‘doing Joe Wicks’ added to our lockdown schedules and vocabulary.
But might embracing regular exercise (at last!) offer us some protection from acute respiratory infections? This is an important question, and especially in this era of COVID. Of all acute illnesses, these are the most common. They range from the common cold to illnesses such as pneumonia and now coronavirus.
Regular exercise offers health benefits that include better maximal oxygen uptake (VO₂ max), muscular strength, flexibility, and body composition. In theory, it could affect our susceptibility to acute respiratory infections by improving our immune function and stress resistance.
Evidence on exercise and acute respiratory infections
A Cochrane Review Exercise versus no exercise for the occurrence, severity, and duration of acute respiratory infections (April 2020) brought together the best available evidence on whether exercise has an effect on the number of acute respiratory infections people get over the course of a year, on how severe the symptoms are and on how long the illness lasts.
The review authors looked for studies up to 5 March 2020. They were able to include 14 studies involving 1377 healthy people aged 18 to 85, who were randomly put into groups to do regular exercise or no exercise. Exercise was mostly supervised and took place at least three times a week, typically sessions of 30 to 45 minutes of moderate-intensity exercise such as walking, cycling, treadmill, or a combination. We don’t know what kind of acute respiratory infections people in the studies got.
Here’s what they found
When healthy people did regular exercise, compared with not exercising, this may have reduced the severity of symptoms when they got an acute respiratory infection and the number of days symptoms lasted whilst people were enrolled in the studyAn investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies..
However, exercise may have made little or no difference to the number of acute respiratory infections healthy people got in a year, or the proportion of people getting at least one, or the number of days symptoms lasted during each period of illness.
How certain can we be about these results?
Problems with the design of studies and the way they were done mean that the evidence was assessed as being ‘low certainty’, so we can’t be confident that these results are accurate. They may change when more and (hopefully) better studies are available to add to the review.
What about harms?
With any interventionA treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include a drug, surgery, exercise or counselling. (regular exercise in this case) it’s important to consider potential harms such as injuries. However, only one study here did this, so there is uncertainty about that too.
Where does this leave us?
Despite remaining uncertainties about possible effects of regular exercise on our susceptibility to acute respiratory infections, there are many established benefits to doing it. In extraordinary times, many of us have discovered a range of benefits for ourselves. Let’s hope that more and better research will provide clearer answers to the question of whether it can reduce our susceptibility to respiratory infections.
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Grande AJ, Keogh J, Silva V, Scott AM. Exercise versus no exercise for the occurrence, severity, and duration of acute respiratory infections. Cochrane Database of Systematic ReviewsIn systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. 2020, Issue 4. Art. No.: CD010596. DOI: 10.1002/14651858.CD010596.pub3.
Sarah Chapman has nothing to disclose.