Getting in a couple of hours of exercise every week won't only help to keep you fit, it could also help you to stave of the flu. New research from Flusurvey - run by the London School of Hygiene and tropical Medicine - revealed that undergoing around two and a half hours of vigorous exercise could help to reduce the likelihood of developing flu.

Flusurvey's online questionnaire received answers from around 4,800 people this year and found the levels of flu have been reasonably low throughout the winter. The results also found that those who undertake moderate exercise are not better protected against the illness, whereas  vigorous exercise helps to reduce the effects of flu.

The survey, which has now been running for five years, attempts to track as much information as possible concerning who gets flu and who doesn't. When registering, people are asked how much vigorous exercise they undertake each week, such as cycling, running or participating in competitive sports. People then have to log in each week to record whether they have any flu-like symptoms and to say how they are feeling in general.

The survey found that around 100 flu cases per every 1,000 people might be prevented by undertaking several hours of vigorous activity each week. Researchers also noted that this winter has seen the lowest number of reports of flu and flu-like illnesses in several years.

Throughout this winter, only 4.7 per cent reports via the online survey were positive for a flu-like illness. This is down from the six per cent reported in 2013. Lower levels of flu were also reported in children with flu-like illnesses, falling from 7.9 per cent last year to five per cent during this winter.

Dr Alma Adler, from the London School of Hygiene and Tropical Medicine, said: "We need to treat this result cautiously as these are preliminary findings. However, they are consistent with findings for other conditions and really show the health benefits of exercise.

"Although many people have dodged the flu bullet this winter, flu can occur at any time, so taking advantage of the better weather is a great opportunity to get out and get fit to ward off flu this spring."