HEALTH
Scientists focusing on how
exercise raises immunity
Melissa Mitchell,
News Editor
(217) 333-5491; melissa@illinois.edu
7/1/03
CHAMPAIGN, Ill. — An increasing number of doctors and other health experts
have been encouraging older adults to rise from their recliners and go for a
walk, a bike ride, a swim, or engage in just about any other form of physical
activity as a defense against the potentially harmful health consequences of
a sedentary lifestyle.
"Exercise is touted as a panacea for older adults," said Jeffrey Woods,
a kinesiology professor at the University
of Illinois, who noted that fitness programs are routinely recommended for people
with various health problems – from diabetes to heart disease. Health
experts generally recognize that this population benefits from physical fitness,
he said. What they don’t know is why exercise appears to have certain
preventive and restorative health effects. Also unknown is what – if any
– relationship exists between exercise and immune functioning.
"Despite the numerous benefits of exercise – for example, improving
cardiovascular and muscular fitness – we know very little about how exercise
affects the immune systems of older adults," Woods said. "Good, bad
or indifferent, this information could have important public health consequences
for our aging population." For that reason, Woods and colleagues in the
university’s kinesiology department are conducting research that seeks
to establish the link between exercise training and immune function. The field,
he said, is still in its infancy, with Illinois researchers among those who
are defining it.
"Our laboratory is using both animal and human models to address the extent
to which exercise affects immune functioning and susceptibility to infectious
disease in older populations," Woods said. "We have obtained some
exciting preliminary data in mice that suggest that moderate exercise or training
may boost some immune function measures and reduce mortality caused by influenza.
While we don’t have corollary evidence yet in people, we are in the midst
of conducting a large clinical exercise trial in older adults, funded by the
National Institute on Aging, that will provide definitive evidence as to whether
moderate exercise training influences immune function."
In the meantime, results of one study conducted in Woods’ lab, published
in the current online edition of the journal Brain, Behavior and Immunity, indicates
that exercise training increases the ratio of naïve T cells to memory T
cells in the spleens of older mice. The finding is potentially significant,
he said, because, on this measure, "we turn old mice into young mice."
When people and animals age, he explained, the thymus, which produces naïve
T lymphocytes, shrinks, thus producing fewer naïve cells. "This is
one reason that older people/animals have trouble responding to new environmental
pathogens."
And with the recent appearance of so many new environmental pathogens – from West Nile Virus to SARS and monkeypox – Woods said the ability to boost the immune systems of the elderly, who are among the populations most at risk from infection, is a worthy goal.