Research
Boost Immune System
Regular Exercise May Protect Against Negative Effects
Of Stress On Immune System
11-12-1998
A new University of Colorado at Boulder study suggests that
choosing to exercise regularly in moderation may help guard
against the negative effects of stress on the body's immune
system.
People
who exercise regularly are less likely to get sick after
stressful situations than people who don't exercise, said
Assistant Professor Monika Fleshner of the department of
kinesiology and applied physiology at CU-Boulder. Doctors
know exposure to mental or physical stress can increase
susceptibility to and severity of disease.
Fleshner's
study measured the effect of stress on immune responses
in laboratory rats that could either choose to exercise
or remain sedentary. Rats that began running on a wheel
for four weeks prior to exposure to stress were protected
against the suppressive effect of stress exposure on immune
response.
But
rats that either began running on the day of stress or that
remained sedentary suffered the negative effects of stress
exposure, she said. Fleshner will present her findings on
exercise and the negative effects of stress Nov. 10 at the
annual meeting of the Society for Neurosciences, to be held
in Los Angeles.
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Although
Fleshner's study was done with animals, it could have important implications
for people. "If a person who regularly exercises in moderation
is under stress, that person is less likely to get sick than someone
who has been sedentary and faces the same challenge," she said.
"This
suggests that what we need to do is keep our exercise programs going
and keep moderate, regular and voluntary exercise going," she
said. "Then when we are hit with our deadlines or stress at work,
marital stress or loss of a loved one, we may be able to better buffer
those negative effects of stress on the immune system."
To reap
the benefits of exercise, the exercise program needs to begin before
the stressful situation, she said. A person who begins exercising
on the day the stress begins will not prevent the negative effects
of stress on the immune system.
For the
study on exercise and the negative effects of stress, six groups containing
10 adult male rats each were assigned to one of the following groups:
wheel running before and after stress; wheel-running only after stress;
no wheel running and stress; or one of three no-stress control groups,
Fleshner said.
The animals
were injected with a foreign protein called keyhole limpet hemocyanin,
or KLH, so the status of their immune systems could be assessed. They
were injected immediately before exposure to a 90-minute laboratory
stress that is known to suppress immune response. The injection stimulates
an immune response similar to that produced by a vaccination, she
said.
The level
of the immune response was determined by measuring antibodies in the
blood against KLH. Blood samples were taken once a week for five weeks
after the KLH injection. The results revealed that only the rats that
ran before and after the stress were protected against the suppressive
effect of stress on the antibody response to KLH.
Rats
that were sedentary or began running on the day of stress exposure
had suppressed antibody responses to KLH, Fleshner said.
The study
on exercise and the negative effects of stress was a logical extension
of her previous experiments on rats and stress, which found forced
exercise is stressful and can actually suppress several measures of
immune function. But if individual rats are able to exert control
over the type, intensity and duration of their physical activity,
exercise can benefit the immune system, she said.
The future
goal of her research is to understand the neuro-hormonal adaptations
produced by exercise that protect against the negative effects of
stress, Fleshner said.
This
article on exercise and the negative effects of stress has been adapted
from a news release issued by University Of Colorado At Boulder, www.colorado.edu.
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