MONDAY, Nov. 1 (HealthDay News) -- There may not be a cure for
the common cold, but people who exercise regularly seem to have
fewer and milder colds, a new study suggests.
In the United States, adults can expect to catch a cold two to
four times a year, and children can expect to get six to 10 colds
annually. All these colds sap about $40 billion from the U.S.
economy in direct and indirect costs, the study authors
But exercise may be an inexpensive way to put a dent in those
statistics, the study says.
"The physically active always brag that they're sick less than sedentary people," said lead researcher David C. Nieman, director of the Human Performance Laboratory at the Appalachian State University, North Carolina Research Campus, in Kannapolis, N.C.
"Indeed, this boast of active people that they are sick less often is really true," he asserted.
The report is published in the Nov. 1 online edition of the
British Journal of Sports Medicine.
For the study, the researchers collected data on 1,002 men and
women from ages 18 to 85. 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 quizzed about their
lifestyle, dietary patterns and stressful events, all of which can
affect the immune system.
The researchers 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 largely sedentary group.
The group that felt the fittest also experienced 34 percent fewer
days of cold symptoms than those were felt 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, the researchers note.
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 researchers
But 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, Nieman's group found.
Nieman said one explanation for the finding could be that
exercise activates the immune system at a higher rate than normal
and causes immune cells to attack viruses. "Exercise gets these
cell circulating around the body; they engage the enemy and deal
with them," he said.
This effect happens each time you exercise, and then the immune
system returns to normal until you exercise again, Nieman said,
adding, "Any aerobic exercise should give you these immune
Infectious disease expert Dr. Marc Siegel, an associate
professor of medicine at New York University, agreed that "exercise
plays a major role in immune response."
However, Siegel added that people who are physically fit may
report fewer sick days because they are "more macho." Perceived
wellness may counter feelings of feeling ill, he noted.
But the effect is not purely psychological, Siegel added. "It's
a combination of psychological and physical factors," he said.
Siegel noted that a lot more work needs to be done to fully
understand the effect of exercise on the immune system. "But the
idea that the immune system is revved up when you are exercising
and better able to defend you I believe is true."
For more on the common cold, visit the
U.S. National Library of Medicine.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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