Regular exercise wards off common cold

The research found the severity of common cold symptoms fell by 41 percent in those who were the fittest and by 31 percent among those who were the most active, the British Journal of Sports Medicine says.

People who were physically active five or more days a week suffered symptoms for almost half the time of those who exercised on only one day of the week or less often, the Daily Mail reported.

Researchers from North Carolina in the US said bouts of exercise spark a temporary rise in immune system cells circulating in the body. Although these levels reduce again within a few hours, each bout of exercise is likely to enhance the body's surveillance of harmful viruses and bacteria that reduce the number and severity of infections, such as the common cold, they said.

The team studied 1,000 adults up to the age of 85 whose health was tracked for 12 weeks during the autumn and winter of 2008. The researchers examined how much aerobic exercise each participant did and rated their fitness levels.

They were also asked about other aspects that can affect the immune system such as lifestyle, diet and recent stressful events.