Journal Archive > 2002 > January

Aching knees

Exercise those osteoarthritic knees

Chances are you or someone you know has knee pain as a result of osteoarthritis (OA). In fact, more than 10 percent of people over age 65 have this condition. Research has shown that osteoarthritic pain can be relieved through the use of non-steroidal anti-inflammatory medications, but drugs do not address the muscle weakness associated with knee OA nor the accompanying pain and loss of function. But what about exercise?

Colorized X-ray of a knee illustrating arthritis © Phototake Scientific

As part of her doctoral work at Tufts, Kristin Baker, N99, designed a study to test the effects of a high-intensity, home-based, strength-training program on the symptoms of knee OA. It has been suggested that muscle weakness, especially in the quadriceps, is a risk factor for the development of the disease. Although previous studies have confirmed strength training reduces osteoarthritic pain, the results have been modest at best, with strength increases minimal in the majority of studies.

Little research has been done on the benefits of strength training where the object is to actually increase strength. Collaborating with Baker on this study was her advisor, Miriam Nelson, associate professor and scientist in the Nutrition, Exercise Physiology and Sarcopenia Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging.

Baker and colleagues took a sample of 46 patients and randomized them to either a strength-training program or a nutrition education program, which served as the control group. Of these 46 patients, 38 completed the study. All patients had to fulfill certain criteria to participate in the study, such as evidence of knee OA on X-ray and symptoms of discomfort. “They had to have pain on most days of the previous month to get into the study,” explains Baker. “If they are not in pain, it is a different question. We were trying to address the symptom question, pain and function.”

Patients in the exercise group were given an instruction booklet of functional and isotonic exercises and 20-pound progressive ankle weights. They performed two sets of each exercise three times a week for a total of four months. By making this a home-based exercise study, the researchers wanted to simulate a real-life setting. As Baker points out, “Most people do not have access to the equipment and trainers that are part of laboratory studies.” Patients were visited at home 12 times during the four-month period.

The results, published in the Journal of Rheumatology in July, are a strong argument for doing strength-training exercises. Patients in the exercise group had on average a 71 percent improvement in knee extension strength in the leg they had deemed most painful as opposed to only a 3 percent improvement rate in the control group. Self-reported pain and physical function improved by 36 percent and 38 percent respectively in the patients who did the exercises; for those in the control group, self-reported pain only improved by 11 percent and physical function by 21 percent.

Baker’s study shows for the first time that patients with knee OA are able to safely follow a strength-training program at home. Along with improvements in muscle strength, function and pain, she and her team also found improvements in quality-of-life surveys. Baker recommends this program to those with pain and limited function due to knee OA, as well as those who are at high risk for the disease—people over age 50 or who are overweight, those with a previous knee injury, muscle weakness or family history and women.

To become familiar with the exercises, Baker suggests that participants might want to work with a certified trainer for a few sessions (contact the National Strength and Conditioning Association for a list of trainers). In addition, two books might be helpful: Miriam Nelson’s, Strong Women Stay Young and Wayne Westcott’s Strength Training Past 50.

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