Exercise may neither help nor harm older kneesNEW YORK (Reuters Health) — Middle-aged and older adults who exercise may not be reducing their risk of knee arthritis, but they aren’t increasing the risk either, research published Wednesday suggests.The question of whether exercise helps or harms older knees has lacked a straightforward answer. Some studies have suggested, for instance, that exercise might help prevent knee osteoarthritis (OA) by increasing the thickness of the cartilage cushioning the joint.

On the other hand, some studies have found that older adults who exercise have a higher rate of knee OA. In particular, there’s some concern that overweight adults, who already have extra stress on the knee joints, might further raise their odds of arthritis through exercise.

In the new study, researchers followed the rate of knee arthritis development among nearly 1,300 men and women for about nine years; the average subject age at the beginning of the study was 53 years. Overall, participants who regularly walked, jogged or otherwise worked up a sweat were at neither greater nor lower risk of developing knee OA, Dr. David T. Felson, of the Boston University School of Medicine, and associates report.

This was true regardless of body weight and type of exercise, according to the report in the journal Arthritis & Rheumatism.

Even though exercise didn’t ward off knee arthritis, the findings can be seen as good news, Felson, the study’s lead author, told Reuters Health. Moderate, recreational exercise does at least appear safe for older knees.

A separate study published in the same journal issue suggests that, similarly, exercise may not affect the progression of knee OA after it’s diagnosed.

In a review of 36 previous studies, researchers in the Netherlands found that, taken together, the research showed no consistent evidence that exercise altered the progression of knee OA. The review also found that a host of other factors were similarly unrelated to OA progression — including the severity of knee pain, the severity of the joint damage on X-rays, thigh muscle strength and history of knee injury.

Regarding the factors that do boost the risk of developing knee OA, Felson said that being overweight or obese “clearly increases” middle-age and older adults’ risk. Recent research also suggests that a number of more subtle differences among people influence the odds of knee OA, according to Dr. Marian A. Minor, a professor of physical therapy at the University of Missouri in Columbia. Among these are leg alignment — being “bow-legged” or “knock-kneed”; the knee joint’s ability to sense position and speed of motion; and job activities like squatting and heavy lifting, explained Minor, who wrote an accompanying editorial.

For now, she told Reuters Health, it seems that moderate activities like walking and jogging are not risk factors. “It’s fairly safe to say now that moderate daily physical activity does not increase risk.”Binge-eating is major US health problemBOSTON (Reuters) — Out-of-control binge eating is the biggest eating disorder in the United States, more common than anorexia and bulimia combined and contributing to a rise in obesity, researchers said on Thursday.Binge eating afflicts 3.5 percent of US women and 2 percent of men at some point in their lives, according to a study by psychiatric researchers at Harvard University Medical School and its affiliate, McLean Psychiatric Hospital.

“I suspect that the connection that we have drawn in this study is just the tip of the iceberg of the problem of out-of-control eating and its relationship to obesity,” Dr. James Hudson, the study’s lead author, told Reuters.

He said binge eating — where people cannot stop from eating well beyond the point of being full at least twice a week — is a chronic and persistent condition in the United States that is under-reported and under-diagnosed. “The most striking finding of the study is the emergence of binge eating as a major public-health problem,” Hudson said. The researchers surveyed more than 9,000 people from 2001 to 2003 in the first national survey of eating disorders.

It said about 0.9 percent of women and 0.3 percent of men reported suffering at some point from anorexia nervosa — a disorder characterised by refusing to eat and an obsessive desire to be thin. It said 1.5 percent of women and 0.5 percent of men reported the condition of bulimia, in which binge eating is followed by attempts to compensate by methods such as self-induced vomiting or excessive use of laxatives or exercise.

It also found a “surprisingly high” proportion of men with anorexia and bulimia <\m> at one-fourth of the reported cases for each of those disorders.

“We believe that the estimates for binge-eating disorder are really under-estimates. That people are often very ashamed of this behaviour, and for everyone who is willing to talk about it in a face-to-face interview there are others who don’t bring it up or don’t elaborate,” Hudson said.