WebMD Medical News
Louise Chang, MD
Nov. 30, 2009 (Chicago) -- Weekend warriors, take note: Too much exercise
may place you at risk for arthritis.
A new study shows that middle-aged men and women who engage in high levels
of physical activity -- at home and at work as well as at the gym -- may be
unwittingly damaging their knees and increasing their risk for
The study involved men and women of healthy weight, without pain or other
symptoms. Knee injuries were more common and more severe among those who
engaged in the highest levels of physical activity, says Christoph Stehling,
MD, of the University of California, San Francisco, and the University of
Muenster, in Germany.
The findings were presented at the annual meeting of the Radiological
Society of North America (RSNA).
Doctors aren't sure that painless cartilage and bone damage can lead to
osteoarthritis, but they think they do, says RSNA spokesman Joseph Tashjian,
MD, president of St. Paul Radiology, in Minnesota.
What is known, he tells WebMD, is that high-impact, weight-bearing
activities such as running and jumping are worse for knee health and carry a
greater risk of injury over time.
"Conversely, low-impact activities, such as swimming and cycling, may
protect diseased cartilage and prevent healthy cartilage from developing
disease," Stehling says.
Osteoarthritis, in which the wear and tear of joints over the years leads to
the breakdown of cartilage, affects about 27 million Americans, according to
The study involved 136 women and 100 men, ages 45 to 55, within a healthy
weight range. The participants were separated into low-, middle-, and
high-activity groups based on their level of physical activities, which
included everything from running to yard work and washing the kitchen
"A person whose activity level is classified as high typically might engage
in several hours of walking, sports or other types of exercise per week, as
well as yard work and other household chores," Stehling says.
The researchers took MRI scans of study participants' knees, looking for
signs of bone, joint and cartilage damage.
Results showed that people in the high-activity group had much more damage,
including cartilage and ligament lesions and buildup of fluid in the bone
marrow, than those in the low-activity group.
For example, 93% of people in the high-activity groups suffered cartilage
damage vs. 60% in the low-activity group. And cartilage damage was three
times more severe in the high-activity group.
The participants' age or sex didn't affect their risk of knee injury,
The researchers are continuing to follow the participants to see if those in
the high-activity group actually develop arthritis and if low-impact vs.
high-impact activities affect their risk.
SOURCES95th Annual Meeting of the Radiological Society of North America, Nov.
29-Dec. 4, 2009, ChicagoChristoph Stehling, MD, University of California, San Francisco; University
of Muenster, Germany.Joseph Tashjian, MD, president, St. Paul Radiology, Minnesota.
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