Taking off weight takes pressure off knees, feet
Moderate weight loss can make big difference
People who find they are experiencing knee, ankle, and foot pain might find better relief in a low-fat diet than in pain relievers.
As bad as those extra pounds might look in the mirror, they feel even worse to the knees, according to Stephen Messier, PhD, a professor of health and exercise science at Wake Forest University who has done extensive research on the knee pain, osteoarthritis, and the relationship of weight loss and moderate exercise to both complaints.
Messier, professor of health and exercise science at Wake Forest, was principal investigator for two studies that sought to identify the effect of weight and exercise on osteoarthritis and the correlation of weight loss to the amount of stress placed on the knees.
What Messier and his colleagues found is that in overweight and obese older adults, every pound lost netted a four-pound reduction in pressure exerted on the knees.
To emphasize the difference it could make for people who spend much of their day on their feet, Messier points out that the benefits to losing 10 pounds can be dramatic.
"For people losing 10 pounds, each knee would be subjected to 48,000 pounds less in comprehensive load per mile walked," he says. His findings were reported in a recent article in Arthritis & Rheumatism, the journal of the American College of Rheumatology.1
Messier’s study reports on 142 overweight and obese older adults with osteoarthritis of the knee. The participants followed an 18-month weight loss program, resulting in an average body weight loss of 2%.
Messier says there are no studies showing that weight loss slows the progression of osteoarthritis of the knee, but that the discovery of the 4-pound pressure reduction for every pound lost warrants research into that area and holds promise for treating and perhaps preventing the disease.
Moderate exercise helps knees
The study by the Wake Forest team was prompted by findings from an earlier study by the university that was published in 2004. Messier reported in that paper on the findings of the Arthri-tis, Diet, and Activity Promotion Trial (ADAPT)2 that moderate weight loss achieved by a combination of diet and moderate exercise was an effective treatment for osteoarthritis of the knee. That study was named by the Arthritis Foundation as one of the top 10 arthritis advances of 2004.
The ADAPT study found that participants in an 18-month program of exercise and calorie-restricted diet had a 24% improvement in physical function, and a 30% decrease in knee pain.
ADAPT measured improvement in physical function, pain, and mobility in 252 people, all of whom were age 60 or older, who were overweight, sedentary, and had knee pain or knee osteoarthritis. The participants were divided into one of four groups: exercise only, dietary weight loss only, dietary weight loss plus exercise, and a control
group that participated in neither diet nor exercise.
Messier explains that the exercise group did aerobic and resistance activities for one hour, three times a week; the diet group attended regular meetings on changing their eating habits and reducing calories in their diets; and the combination group, where the most improvement was measured, participated in both programs.
"Considering that side effects often limit the use of drug therapy, and surgical intervention is often ineffective for mild or moderate knee osteoarthritis, our results give strong support to the combination of exercise and weight loss as a cornerstone for the treatment of overweight osteoarthritis patients," Messier says.
Osteoarthritis is the most common form of arthritis, and is the leading cause of disability in the United States. It destroys the cartilage that acts like a shock absorber in the knees, and the resulting pain and stiffness eventually lead to loss of mobility.
Foot pain tied to weight, too
Overweight also can lead to foot problems, according to findings from a survey of more than 6,000 people conducted by the American Orthopaedic Foot and Ankle Society (AOFAS).
AOFAS reports that foot and ankle problems can be linked to an individual’s weight and body mass index (BMI). The CDC calculates BMI by dividing a person’s weight in pounds by their height in inches squared, and multiplying the product by 703.
The survey found that people with foot and ankle pain who had undergone prior foot surgery or had seen a physician about foot and ankle pain tended to have higher BMIs than those who reported they did not have foot and ankle pain.
Tellingly, nearly 41% of those who said they have foot and ankle pain also said they had gained weight prior to the onset of pain.
"It’s important for the public to know that obesity isn’t just an aesthetic issue, but a contributing cause of musculoskeletal health problems, specifically with the feet and ankles," explains Stuart D. Miller, MD, a Baltimore physician and member of the AOFAS Public Education Committee.
While problems vary from patient to patient, foot and ankle pain often occurs in weight-bearing areas as well as in the tendons and ligaments. Common foot problems include posterior tibial tendonitis, pain in the tendon that runs along the inside of the ankle and the foot; plantar fasciitis, an inflammation in the thick ligamentous connective tissue that runs from the heel to the ball of the foot; and hindfoot arthritis, an inflammation in the back part of the foot.
"In general, people carry approximately four to six times their body weight across the ankle joint when climbing up stairs or walking steep inclines," according to Miller. "Obesity may significantly increase the impact."
References
1. Messier SP, Gutekunst DJ, Davis C, et al. Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis. Arthritis Rheum 2005; 52:2,026-2,032.
2. Messier SP, Loeser RF, Miller GD, et al. Exercise and dietary weight loss in overweight and obese older adults with knee osteoarthritis: The Arthritis, Diet, and Activity Promotion Trial. Arthritis Rheum 2004; 50:1,501-1,510.
[For more information, contact:
- Stephen Messier, PhD, Professor of Health and Exercise Science, Wake Forest University, Winston-Salem, NC. E-mail: [email protected].
- Stuart D. Miller, MD, Orthopedic Surgeon, Greater Chesapeake Orthopaedic Associates, Baltimore. Phone: (410) 554-2270.]
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