(HealthScoutNews) -- Welcome to cold season. Time to make sure you've stocked up on tissues and chicken soup to help you get through the inevitable bout with a runny nose, watery eyes and sore throat.

What if there was a way to ward off the misery?

Exercise might just do the trick.

A recent study found that people who are physically active had fewer colds than couch potatoes.

Researchers analyzed a year's worth of health and exercise data on 547 healthy adult men and women. The study found people who were the most active had 25 percent fewer colds than people who were the least active.

Those who were moderately active also had fewer colds than people who were the least active, but the difference wasn't as striking, says Charles E. Matthews, author of the study and a research assistant professor of epidemiology at the University of South Carolina.

The researchers looked at physical activity done in the home, at work and during leisure time. They considered only moderate to vigorous exercise, including activities such as brisk walking, scrubbing floors or heavy gardening -- mowing the lawn, for instance. Vacuuming or dusting wouldn't qualify, Matthews says.

After controlling for major diseases, age, diet, having young children in the household and psychological factors such as anxiety and hostility, they found that people who were the most active had the fewest colds.

The average number of colds for the year among people in the study was 1.2.

"The most likely explanation for the finding is that higher levels of activity for the average person derive some benefits to their immune defenses against a cold," Matthews says.

Some researchers believe that both too little exercise and too much exercise can adversely affect the immune system. For example, previous research has shown that training for a marathon can have a negative impact on the body's ability to fend off colds and other viruses.

Matthews says his study shows people at the very low end of the exercise scale also were at higher risk of falling victim to a cold.

How does exercise improve your chances of beating the cold virus?

Physical activity may cause an increase the production of immunoglobulins, a component of the immune system that fights off infections. Immunoglobulins are found in the nasal tract, the first place that the cold virus attacks the body, Matthews says.

His study appeared in a recent issue of the journal Medicine and Science in Sports and Exercise.

However, some doctors remain skeptical of the new research.

Dr. Jack Gwaltney, a professor of internal medicine at the University of Virginia School of Medicine, has spent 40 years researching colds. He says he has yet to see solid evidence that exercise has anything to do with warding off colds.

It's exceedingly difficult to create a placebo-controlled, double-blind study -- the standard of medical research -- for such a study for one simple reason: People who exercise know they're exercising, while people who are told not to exercise know they're not, Gwaltney says.

This opens the possibility of biased results.

"I don't know of any convincing evidence that exercise prevents colds or helps you get over colds," Gwaltney adds.

More than 200 viruses are known to cause the symptoms of a common cold. Adults average from two to four colds a year, according to the National Institute of Allergy and Infectious Diseases (news - web sites).

Symptoms of a cold usually begin 12 hours after infection and include nasal discharge, swelling of the sinus membranes, sneezing, sore throat, cough and headache, Gwaltney says. Cold symptoms can last from two to 14 days, but two-thirds of sufferers recover within a week.

How about the wisdom of exercising if you already have a cold?

You don't have to take it lying down. Research shows moderate exercise had little effect on the duration or severity of a cold.

Tom Weidner, director of the athletic training research and education laboratories at Ball State University in Indiana, divided 45 men and women into two groups and inoculated them with a cold virus.

Half were put on an exercise program. Half took it easy.

The study found no difference in how long their cold lasted or its severity, he says.

"If a person is comfortable during exercise, then they can go ahead and exercise," Weidner says. "If they're feeling uncomfortable, then they should rest."

But the same doesn't hold true for the flu.

Symptoms of the common cold are generally from the neck up. The flu, on the other hand, is a more serious illness that can cause lung congestion, aches, fever and intense fatigue.

The flu can interfere with blood oxygen levels, while head colds do not, Gwaltney says. "Thus, exercising during the flu might lead to more serious medical problems."

What To Do

The National Institute of Allergy and Infectious Diseases and the U.S. Centers for Disease Control and Prevention have more information about the common cold.

Reference Source 101

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