(RxWiki News) Diet and exercise are two things that heavier adults are told to consider when seeking relief from pain in the knees. With osteoarthritis, exercise by itself might not be enough to reduce the stress placed on those joints.
New research showed that losing at least 10 percent of body weight either through dieting alone or dieting with exercise was more effective at reducing pain and pressure on the knees among older patients with osteoarthritis than exercise alone.
The two strategies combined could help patients safely achieve long-term weight loss to improve osteoarthritis symptoms better than using either strategy on its own, according to researchers of this study. Intensive weight loss could improve knee function and inflammation.
"Talk to your doctor about a safe exercise program."
Stephen P. Messier, PhD, from the Department of Health and Exercise Science at Wake Forest University in North Carolina, led this study that aimed to see whether patients with osteoarthritis in the knees could move better and have less pain by reducing their body weight by at least 10 percent.
The study included about 450 patients over age 55 who were overweight and obese, as determined by having a body mass index (BMI) between 27 and 41. BMI is a measure of height and weight that shows whether a person is of normal weight or overweight.
The patients were randomly assigned to one of three weight-loss strategies to follow from July 2006 to April 2011. The weight loss strategies consisted of diet with exercise, diet alone and exercise alone.
To test how well patients could move, the researchers measured how far they could walk in six minutes and the level of compressive force on the knee joint.
They also measured levels of a protein called plasma interleukin-6, or IL-6, as a marker of inflammation in the body.
The participants also reported their level of pain on a scale of 0 to 20 and function on a scale of 0 to 68. Mobility and health-related quality of life were also measured using a scale of 0 to 100.
The weight loss programs were performed at Wake Forest University. The exercise groups were able to take their exercise programs home after the first six months, or continue to work out at the facility.
By the end of the 18-month weight loss program, 88 percent, or 399 participants, completed the study.
Participants in the diet with exercise group and in the diet-alone group had more weight loss and greater reductions in IL-6 levels compared to the exercise-alone group, the researchers found.
On average, the diet-alone group lost 9.5 percent of their body weight and the diet with exercise group lost 11.4 percent of their weight at the end of the 18-month period. In comparison, the exercise group lost 2 percent of their body weight.
The diet with exercise group also had less knee pain, a faster walking speed and improved function compared to the exercise-alone group.
Specifically, 38 percent of the diet with exercise group reported little or no pain after 18 months. At the same time, 20 percent of the diet group and 22 percent of the exercise group reported little to no pain.
Participants in the diet with exercise group walked 21.3 meters, or about 70 feet, farther than the exercise group when timed for six minutes. The diet with exercise group also walked 41.5 meters, or about 136 feet, farther than the diet group.
Reductions in knee compressive force were greater among those in the diet group compared to the exercise group after 18 months.
The exercise and diet groups reduced the load on the knee joints by 5 percent and 10 percent, respectively. The diet with exercise group reduced load by 9 percent.
Physical health-related quality of life was also better among participants in the diet with exercise group compared to the exercise-alone group.
And both the diet with exercise and diet-alone groups had greater reductions in IL-6 levels.
"The findings … suggest that intensive weight loss may have both anti-inflammatory and biomechanical benefits; when combining weight loss with exercise, patients can safely achieve a mean long-term weight loss of more than 10 percent, with an associated improvement in symptoms greater than with either intervention alone," the researchers wrote in their report.
The authors noted a couple of limitations with their study. One limitation was that all the participants had about the same level of osteoarthritis pain, so it is unclear whether the weight loss programs would work to the same extent among patients with greater levels of pain.
A second limitation of the study was that the technique used to measure compressive force on the knee didn't take all knee ligaments and smaller muscle units into account. However, the researchers said they successfully used the method in previous investigations.
Several of the authors received grants, payments and royalties for lectures, testimonies and services on various councils and institutions that were not affiliated with the study.
The National Institutes of Health, the National Institute of Arthritis and Musculoskeletal and Skin Diseases, the National Institute on Aging, the National Center for Research Resources and General Nutrition Centers funded the study.
The study was published online September 25 in the journal JAMA.