To read the full review go to Exercise versus no exercise for the occurrence, severity, and duration of acute respiratory infections

Plain language summary

Review question

Does exercise change the occurrence, severity, or duration of acute respiratory infections such as the common cold, influenza, cough, and sore throat?

Background

Exercise has been shown to improve health generally. We reviewed the evidence to find out whether exercise is also effective at changing the occurrence, severity, or duration of acute respiratory infections (colds and coughs) that last less than a month.

Search date

We searched for studies up to 5 March 2020.

Study characteristics

We added evidence from three trials (473 participants) for this update, for a total of 14 trials involving 1377 participants, aged 18 to 85 years. Exercise was supervised and prescribed at least three times a week, with 30 to 45 minutes of moderate-intensity activities in most trials.

Study funding sources

Seven studies were funded by public agencies; five studies did not report funding; and two studies were funded by private companies.

Key results

It is unclear whether exercise changed the number of acute respiratory infections a person experiences each year; the number of people who experienced at least one acute respiratory infection during the study period; or the number of days with symptoms during each episode of illness. Exercise reduced symptom severity and the number of days symptoms lasted whilst participants were enrolled in the trial. We are uncertain whether exercise has an important effect on other outcomes, such as effects measured by laboratory tests (blood and salivary samples), quality of life, cost-effectiveness, or injuries related to exercise.

Certainty of evidence

Overall, the certainty of the evidence was low, which means that further research is likely to impact our conclusions. There is a need for better designed studies to allow a clearer understanding as to whether exercise reduces the occurrence, severity, or duration of acute respiratory infections.