Two-and-a-half hours of vigorous exercise every week cut the chance of catching the flu by approximately 10%, research suggests.
Physical activity which leads to sweating or hard breathing reduces flu or flu-like illness, experts at the London School of Hygiene and Tropical Medicine found.
Walking, light jogging and other gentle sports which did not raise heart rate, were found to have little effect.
The Flusurvey also found overall flu levels across the UK appear to be down on last year, with the influenza season apparently curbed by a lack of illness among children and young people.
More top news
Teenagers are being tricked into sending inappropriate photographs through social media, police say.
June and Barry Steenkamp tell Good Morning Britain they accept the judge's decision but still do not believe Pistorius' version of events.
Fifteen British WW1 soldiers will be reinterred at the Commonwealth War Graves Commission cemetery today, 100 years after their deaths.