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Heart-Healthy Exercise May
Also Be Knee-Healthy Exercise
edited by Joint-Pain-Forum.com
The world's most common joint disease, osteoarthritis (OA) is a major cause of
disability among adults over the age of 50. Whether physical activity is
beneficial or detrimental to weight-bearing joints, knees in particular, has
been open to debate. Some studies implicate physical activity in provoking knee
OA, while others suggest that physical activity may actually protect the knee
joint from the disease. Confounding the matter is the fact that knee injury is a
known risk factor for knee OA. Then, there's the unclear role of osteophytes in
knee OA progression, compounded by the limitations of radiographs for monitoring
small yet significant changes in joint structure.
For a clearer picture
of the impact of physical activity on the knee joint, a team of researchers in
Australia turned to magnetic resonance imaging (MRI). This highly accurate
high-tech tool makes it possible to directly visualize joint structures, detect
early and pre-disease states of OA, and assess the influence of potential risk
factors. Taking advantage of this novel methodology, the researchers studied the
effect of physical activity, in various degrees of intensity, frequency, and
duration, on knee structures in a total of 257 healthy adults between the ages
of 50 and 79, with no history of knee injury or OA. Their findings, presented in
the October 2007 issue of Arthritis Care & Research , suggest that exercise
that is good for the heart is also good for the knee.
Recruited from an
established community-based research population, the Melbourne Collaborative
Cohort Study, subjects all underwent MRI exams on the tibia bone and
tibiofemoral joint of their dominant knee -- the one on the leg they first step
forward when walking. MRI was used to assess cartilage defects and bone marrow
lesions, as well as measure cartilage volume, an indicator of cartilage health
and strength. Loss of knee cartilage is linked to worsening knee symptoms in OA
sufferers. Subjects also answered specific questions regarding their exercise
and walking habits, as well as routine activity at home and at work, to
determine their level of physical activity in both the 6 months and 7 days prior
to the study. To create a baseline for each subject, past information on weight,
height, body mass index, and physical activity, from questionnaires completed
between 1990 and 1994, was obtained. Then, the team performed a series of
analyses and comparisons.
Among the notable findings, both baseline and
current vigorous physical activity -- exercise that gets the heart pumping and
the body sweating -- were associated with an increase in tibial cartilage
volume, free from cartilage defects. What's more, tibial cartilage volume
increased with frequency and duration of vigorous activity. Recent
weight-bearing exercise was also linked to increased tibial cartilage volume and
reduced cartilage defects. Finally, moderate physical activity, including
regular walking, was associated with a lower incidence of bone marrow lesions.
"This is the first study to demonstrate a potentially beneficial effect
of walking on the reduction in the risk of bone marrow lesions in the knee,"
notes the study's leading author, Dr. Flavia M. Cicuttini. "Bone marrow lesions
have been associated with pain and radiograph-defined progression of
osteoarthritis, type II collagen degradation, and loss of cartilage volume."
Demonstrating a protective effect of past and current vigorous physical
activity on knee cartilage in healthy adults, this study strongly supports the
benefits of exercise for older individuals at risk for OA. Though both the
intensity and duration of physical activity had a significant positive impact on
cartilage, the ideal amount of physical activity for joint health remains
unclear. "Our data suggest that at least 20 minutes once per week of activity
sufficient to result in sweating or some shortness of breath might be adequate.
This is similar to, if not somewhat less than, the recommendations for
cardiovascular health," Dr. Cicuttini observes.
www.Joint-Pain-Forum.com from original press release.
Article: "Effect of Physical Activity on Articular Knee Joint Structures in
Community-Based Adults," Tina L. Racunica, Andrew J. Teichtahl, Yuanyuan Wang,
Anita E. Wluka, Dallas R. English, Graham G. Giles, Richard O'Sullivan, and
Flavia M. Cicuttini, Arthritis Care & Research, October 2007; (DOI:
Source: Amy Molnar
John Wiley & Sons,
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