In its Morbidity and Mortality Weekly Report for Oct. 8, the CDC estimates that nearly 50 million Americans have arthritis, and the joint disease is especially common among people who are obese.

The statistic comes from national telephone polling of tens of thousands of adults in 2007 through 2009.

The report also suggests there were about 42 percent adults with arthritis who said their joint pain or other arthritis symptoms limited their usual activities.

That means more than 21 million adults have trouble climbing stairs, dressing, gardening or doing other things, the CDC said.

The percentage of people who were hobbled was more than twice as high in obese people as those who were normal weight or underweight, the researchers found.

Obesity particularly plays a role in the onset of knee osteoarthritis, the most common form of the disorder.

The total cost of medical and impaired activity to the U.S. economy is about 128 billion U.S. dollars annually, the agency added. 

On Xinhua Web site: http://news.xinhuanet.com/english2010/health/2010-10/08/c_13546720.htm

The study, published in the June 28 issue of Archives of Internal Medicine, followed more than 18,000 women between the ages of 25 and 42 for 16 years.

The study found the women who increased physical activities like brisk walking and bicycling by 30 minutes a day during the 16-year period maintained their weight and even lost a few pounds, but those whose exercise was slow walking did not lose any weight.

According to the study, women who started biking for just five minutes a day gained about 1.5 fewer pounds over the course of the study than similar women who didn’t take up biking.

“This is not suggesting that if you bicycle for five minutes you will immediately go back to the weight you were when you were 18,” said Anne C. Lusk, a research fellow at the Harvard School of Public Health and an author of the paper.

But Lusk pointed out biking and walking are easier than many other forms of exercise to incorporate into everyday life.

“It’s highly suggestive that bicycling is highly beneficial in women,” Lusk added. 

On Xinhua Web site: http://news.xinhuanet.com/english2010/health/2010-06/30/c_13376845.htm