Although the most common approach to treating the pain of knee osteoarthritis is with anti-inflammatory drugs, the medications have little effect on disability or the disease process. Health-care practitioners often promote exercise as an alternative method of reducing pain and functional disability. A recent study published in Medicine & Science in Sports & Exercise, the official monthly journal of the American College of Sports Medicine, compared the cost-effectiveness of aerobic exercise with resistance training for people with osteoarthritis of the knees. The results suggest that resistance training for seniors with knee osteoarthritis is more economically efficient than aerobic exercise in improving physical function.

Because it is difficult to assign a dollar value to such intangibles as avoided pain and suffering or quality of additional years of life, a cost-benefit analysis was not performed with this study. Rather, the investigators conducted a cost-effectiveness analysis in which different intervention approaches were compared in terms of their economic efficiency. Basing their analysis from the perspective of a health-care payer, they set out to assess whether aerobic exercise is more or less cost-effective than resistance training, controlling with educational intervention. ” We knew that studies had been done to determine the economic burden of illness, as well as to test different intervention approaches for controlling symptoms of the disease, ” said lead researcher Mary Ann Sevick, Sc.D., who teaches at Wake Forest University School of Medicine. ” But little research has been done comparing the cost-effectiveness of different kinds of physical activity interventions in improving physical function.

We assigned a dollar value to every aspect of each intervention, including the cost of delivering the intervention, the cost of treating and monitoring adverse events and the cost of physician referrals. We also obtained self-reported measurement of physical performance, pain and pain intensity, as well as objective measures of physical performance.”

The study included 439 persons with knee osteoarthritis, recruited from the general population and then randomly assigned to one of three study sections: resistance exercise, aerobic exercise, or an education control group. The researchers gathered data four times: at baseline, and at six, 12, and 18 months. To be eligible for the study, participants needed to be over 60, have x-ray evidence of knee osteoarthritis, pain on most days of the month in one or both knees, and difficulty with one or more of the following: walking, climbing stairs, exiting or entering a car, or with other everyday activities. In order to be part of the study, it was necessary for each person to be minimally functional without the use of a cane or other device.

The aerobic exercise-training program consisted of a three-month facility-based program followed by 15 months of the same exercises at home. Participants were trained in warm-up, stimulus, and cool-down, then were instructed to perform the stimulus (walking) at 50-70% of their heart rate reserve three times a week.

During the home-based period, participants were contacted by telephone and in person biweekly for the first four to six months, then every three weeks by telephone only, then monthly for months 10-18. The resistance program was set up similarly, and included nine exercises (leg extension, leg curl, step up, heel raise, chest fly, upright row, military press, biceps curl, and pelvic tilt) to be performed in two sets of 12 repetitions each on three consecutive days after reaching a weight plateau.

Intervention groups were compared to an education control group, which was intended to control for the possible effects of attention and social interaction. During the first three months, participants received a monthly 90-minute video on general topics related to osteoarthritis. Participants had the opportunity for telephone contact with a nurse to discuss their conditions and medications for the fourth to the 18th month of follow-up. At first this contact was made every two weeks, then monthly until the end of the study.

A variety of functional outcomes were assessed, including: self-reported disability, six-minute walking distance, a timed stair-climb task, a timed lifting and carrying task, time required to get in and out of a car, and measures of pain frequency and pain intensity on moving. These data were combined with estimates of the cost of delivering the interventions to yield cost effectiveness ratios of each intervention group on each outcome variable measured.

Further study to examine the impact of these interventions on long-term cost and utilization of health-care services is warranted; such studies could include utility measures. Clinical conditions in this study did not allow for a condition in which patients received no special instruction about knee osteoarthritis, which would be of zero cost but not efficacious in terms of pain and disability. The clinical significance of this study is not clear, and patients must be informed of the fact that exercise does not cure osteoarthritis, however much it may affect a feeling of well-being, freedom from pain and functional disability. “These outcomes,” says Sevick, “are of more concern to patients than whether or not radiologic evidence shows improvement in their condition.”

Study after study has shown that physical activity mitigates the loss of muscle strength and endurance, indicating that if older adults focus energy on muscular, skeletal, balance and mobility training, they will maintain a functionally superior quality of life well into old age.

Water aerobics, a great alternative.

Manual Resistance Training. A Safe Strength Training Method.

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