PMCID: PMC134175
Community-based exercise program reduces risk factors for falls in 65- to 75-year-old women with osteoporosis: randomized controlled trial - Carter et al
Abstract
Background
Exercise
programs improve balance, strength and agility in elderly people and
thus may prevent falls. However, specific exercise programs that might
be widely used in the community and that might be “prescribed” by
physicians, especially for patients with osteoporosis, have not been
evaluated. We conducted a randomized controlled trial of such a program
designed specifically for women with osteoporosis.
Methods
We
identified women 65 to 75 years of age in whom osteoporosis had been
diagnosed by dual-energy X-ray absorptiometry in our hospital between
1996 and 2000 and who were not engaged in regular weekly programs of
moderate or hard exercise. Women who agreed to participate were randomly
assigned to participate in a twice-weekly exercise class or to not
participate in the class. We measured baseline data and, 20 weeks later,
changes in static balance (by dynamic posturography), dynamic balance
(by a timed figure-eight run) and knee extension strength (by
dynamometry).
Results
Of
93 women who began the trial, 80 completed it. Before adjustment for
covariates, the intervention group tended to have greater, although
nonsignificant, improvements in static balance (mean difference 4.8%,
95% confidence interval [CI] –1.3% to 11.0%), dynamic balance (mean
difference 3.3%, 95% CI –1.7% to 8.4%) and knee extension strength (mean
difference 7.8%, 95% CI –5.4% to 21.0%). Mean crude changes in the
static balance score were –0.85 (95% CI –2.91 to 1.21) for the control
group and 1.40 (95% CI –0.66 to 3.46) for the intervention group. Mean
crude changes in figure-eight velocity (dynamic balance) were 0.08 (95%
CI 0.02 to 0.14) m/s for the control group and 0.14 (95% CI 0.08 to
0.20) m/s for the intervention group. For knee extension strength, mean
changes were –0.58 (95% CI –3.02 to 1.81) kg/m for the control group and
1.03 (95% CI –1.31 to 3.34) kg/m for the intervention group. After
adjustment for age, physical activity and years of estrogen use, the
improvement in dynamic balance was 4.9% greater for the intervention
group than for the control group (p = 0.044). After adjustment
for physical activity, cognitive status and number of fractures ever,
the improvement in knee extension strength was 12.8% greater for the
intervention group than for the control group (p = 0.047). The
intervention group also had a 6.3% greater improvement in static balance
after adjustment for rheumatoid arthritis and osteoarthritis, but this
difference was not significant (p = 0.06).
Interpretation
Relative
to controls, participants in the exercise program experienced
improvements in dynamic balance and strength, both important
determinants of risk for falls, particularly in older women with
osteoporosis.
In
people with osteoporosis, exercise may reduce the risk of fracture by
its effect on maintenance of bone mass and, probably more important, by
improving postural stability and thus decreasing rates of falling.1
Numerous studies have examined the effect of exercise on bone mineral
density in women with normal bone mass. Meta-analyses have revealed that
either aerobic or resistance training can confer a 1% to 2% advantage
relative to control participants, largely by slowing the loss of bone
mineral.2,3,4,5,6 Few exercise interventions have been undertaken in women with osteoporosis,7
but even the limited data available make it clear that antiresorptive
therapy augments bone mineral more effectively than does exercise alone.8,9
There
is, however, increasing evidence that specific exercise interventions
can reduce risk factors for falls and actual falls in older people.10,11,12
Further investigation in women with osteoporosis is therefore
warranted, as these subjects are at particular risk of fracture if they
fall. The response to exercise programs could very well be similar for
women with osteoporosis and those with normal bone health, but this
assumption needs to be tested. There may be disease-related,
physiological, or biomechanical and posture-related differences between
women with osteoporosis and the women in whom exercise and risk factors
for falls have been studied previously.
In a randomized
controlled trial of 10 weeks of physiotherapy in 53 women with vertebral
osteoporosis and back pain, Malmros and colleagues13
showed that static balance (measured by computerized posturography)
improved significantly in the treatment group. In another randomized
clinical trial, physiotherapy-directed exercise in 30 patients with
osteoporosis (not defined) significantly improved static balance
measured by functional reach and quadriceps strength determined with an
isokinetic dynamometer.14
Although both studies showed that exercise programs could improve known
risk factor profiles for falls, they were limited by the small number
of subjects and their short duration (maximum 12 weeks). Neither study
measured both static and dynamic balance, both of which are predictors
of falls.10,11,12,13,15
Lastly, both studies employed hospital-based physiotherapists as
instructors and thus could not be widely used for patients living in the
community.
A large number of tools are available to measure risk factors for falls, such as static and dynamic balance and strength.10
A sophisticated tool for measuring static balance, the Equitest
computerized posturography platform (Neurocom International, Clackamas,
Ore.), is considered by many the gold standard for measuring sway.16
It is reliable and is designed to distinguish the contributions of the
visual, proprioceptive and vestibular systems in maintaining balance,17
but the device measures sway only in the anteroposterior plane, even
though most falls occur to the side. In contrast, a measure of dynamic
balance, the figure-eight run,18 which has previously been used in older people19,20
is simple to perform and does not require special equipment or
training. Quadriceps strength is another independent predictor of both
falls21 and fracture risk,10,22 and it can be measured reliably, simply and cheaply with a strain gauge dynamometer.21
The
Osteoporosis Program at the BC Women's Hospital and Health Centre
developed Osteofit, a community-centre-based exercise program suitable
for people with osteoporosis.23
The program aims to improve participants' static and dynamic balance,
strengthen key muscle groups and ameliorate quality of life. Since its
inception in 1998, over 500 women have participated in the program in
over 50 community centres. Similar programs exist in the United States,
Australia and Europe, but to our knowledge there have been no reports of
the efficacy of any readily accessible community-based exercise
programs on risk factors for falls in women with osteoporosis.
We
tested the primary hypothesis that a 20-week Osteofit exercise program,
provided in a community centre setting with classes of 12 participants
per certified instructor, would improve measures of balance and knee
extension strength in community-dwelling women aged 65 to 75 years in
whom osteoporosis had been diagnosed by dual-energy X-ray
absorptiometry. Our secondary hypothesis was that the intervention would
also improve quality of life24,25 as measured by an osteoporosis-specific quality-of-life index.26 A planned interim report of the trends observed after 10 weeks of intervention has been published elsewhere.27
Quelle und Full Text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC134175/
Full Text / pdf: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC134175/pdf/20021029s00016p997.pdf
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