Exercise helps beat common cold

There may not be a cure for the common cold, but people who exercise regularly seem to have fewer and milder colds.

On an average, adults can expect to catch a cold two to four times a year, and children can expect to get six to 10 colds annually.

Researchers collected data on 1,002 men and women from ages 18 to 85 years in America. Over 12 weeks in the autumn and winter of 2008, the researchers tracked the number of upper respiratory tract infections the participants suffered. In addition, all the participants reported how much and what kinds of aerobic exercise they did weekly, and rated their fitness levels using a 10-point system. They were also asked about their lifestyle, dietary patterns and stressful events, all of which can affect the immune system.

It was found that the frequency of colds among people who exercised five or more days a week was up to 46 percent less than those who were largely sedentary - that is, who exercised only one day or less of the week. In addition, the number of days people suffered cold symptoms was 41 percent lower among those who were physically active on five or more days of the week, compared to the sedentary group. The group that felt the fittest also experienced 34 percent fewer days of cold symptoms than those the least fit. Moreover, colds also appeared to be less severe for those in better shape. Among those who felt the fittest, the severity of symptoms dropped by 32 percent and by 41 percent among those who exercised most.

One limitation of the study was a lack of adjustment for all variables that might affect the outcome, such as exposure to cold germs at work or from children in the home. The study did account for a variety of factors, including age, body mass index and education. And after taking those factors into account, the researchers found that being older, male, and married reduced the frequency of colds. However, the most significant factors (besides being older) were perceived fitness and the amount of exercise a person got.

One explanation for the finding could be that exercise activates the immune system at a higher rate than normal and causes immune system cells to attack viruses. Exercise gets these cells circulating around the body; they engage the enemy and deal with them. This effect happens each time one exercises, and then the immune system returns to normal until one exercises again.

Although, from the above findings it is clear that exercise plays a major role in immune response, more studies are needed to fully understand the effect of exercise on the immune system.