Strengthening exercises for the legs may
help slow the progression of knee arthritis
over the long haul, a study shows.
Researchers found
that among older adults with knee osteoarthritis,
those who underwent lower-body strength training
showed less narrowing in the knee joint space
over 2.5 years -- evidence that their arthritis
was progressing more slowly.
Osteoarthritis is the common, "wear-and-tear"
form of arthritis that often comes with aging.
The cartilage cushioning the joints breaks
down, allowing bones to rub together. Over
time, the affected joint loses its normal
shape, causing further pain and mobility problems.
Other studies have found that strengthening
exercises can, in the short term, ease knee
arthritis symptoms. The new study was unusual
for an exercise trial because it ran for 30
months, looking for differences in X-ray evidence
of arthritis progression, study co-author
Dr. Steven A. Mazzuca stated.
Mazzuca and his colleagues at Indiana University
School of Medicine in Indianapolis followed
221 older adults. Fifty-seven had a diagnosis
of knee arthritis and 164 were recruited from
the general population.
About half were randomly assigned to strength
training that emphasized the lower body, first
at a fitness center and then to a home-based
regimen. The other patients underwent flexibility
exercises and served as a comparison group.
Sixty-seven patients did not complete the
trial, leaving 154 patients for evaluation.
After 30 months, study participants in the
strength training group showed less narrowing
in the knee joint than their counterparts
who performed flexibility exercises.
Strength training slowed the rate of joint
space narrowing by about one quarter, the
researchers report in the journal Arthritis
& Rheumatism.
The benefit was observed despite the fact
that the workouts did not improve strength
in the quadriceps, the group of muscles at
the front of the thigh. Mazzuca said the strength
training group did, however, show less strength
loss -- which typically comes with aging.
But in another, unexpected finding, study
participants who did not have knee arthritis
at the start of the study tended to show more
narrowing in the knee joint when they underwent
strength training.
The reason for this is not clear, according
to Mazzuca. Weakness in the quadriceps, he
noted, is considered a risk factor for knee
arthritis.
Mazzuca said he would hesitate to conclude
that strength training caused the joint space
changes in these study participants. Those
with joint narrowing didn't exercise harder
or show different strength effects than those
whose joint space remained stable, he noted.
More research is needed to confirm this finding,
the researchers write, noting that it's "difficult
to accept" that the strength exercises used
in this study would harm older adults without
knee arthritis.
SOURCE: Arthritis & Rheumatism, October 15,
2006.
