Another Reason To Strengthen Your Quads

Here's another reason to add cycling, squats or lunges to your exercise routine. A new study by researchers at the University of Iowa Hospitals and Clinics found that women with the strongest quads appear to be more protected against the symptoms of osteoarthritis (OA) of the knee than women with weaker quadriceps, or knee extensor muscles. However, men with stronger quadriceps were only slightly more protected from developing symptomatic OA than those with weaker muscles.

Interestingly, quad strength wasn't found to predict the occurrence of OA of the knee as shown in x-rays in men or women, but it did predict the incidence of pain or stiffness in the knee--in women. The findings of the study were published in a recent issue of the journal, Arthritis Care & Research.

The knee is the most common weight-bearing joint affected by osteoarthritis or degenerative joint disease, a major cause of disability in the U.S. The Centers for Disease Control and Prevention (CDC) estimate that 26.9 million U.S. adults are affected by OA. A Medical Expenditure Panel Survey estimates that total out-of-pocket expenditures for treatment of arthritis was $32 billion in 2005.

Neil Segal, M.D., M.S., and colleagues followed 3,026 men and women ages 50 to 79 over a 30-month period in to assess whether knee extensor strength would predict the detection of OA on an X-ray, or symptomatic knee OA. Of those enrolled, a total of 2,519 knees were included in the study of radiographic knee OA and 3,392 knees were evaluated for the combination of radiographic OA and symptoms of OA that include pain, aching or stiffness on most days of the month. the Multicenter Knee Osteoarthritis Study (MOST)

Participants were evaluated for thigh muscle strength and the H:Q ration, the balance of muscle strength between quadriceps (front thigh) and hamstrings (back thigh). X-rays of the knees were taken at the beginning of the study and the conclusion to determine the presence of OA. Telephone screenings at the beginning and end of the study were conducted to establish if frequent pain, aching or stiffness was present in the knee.By the conclusion of the study 48 of 680 men and 93 of 937 women developed OA detected by x-ray. At the end of the 30-month period 10.1 percent of women and 7.8 percent of men displayed signs of symptomatic knee OA. "Our results showed thigh muscle strength was not a significant predictor of radiographic knee OA," concluded the authors. Women in the top third of peak knee extensor strength had a lower incidence of symptomatic knee OA, while men with strong thigh muscles had only slightly better odds of developing OA symptoms compared to men with weaker knee extensor strength.Researchers acknowledge there to be some limitation to the study by not including assessments of hip abductor strength. "Study of hip abductor strength, which is important for control of the knee joint, may be useful in a more comprehensive study of risk for OA of the knee," said Dr. Segal. "These findings suggest that targeted interventions to reduce risk for symptomatic knee OA could be directed toward increasing knee extensor strength," he added.
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