No effect of exercise on knee arthritis

Exercising may not reduce the risk of knee arthritis, but it doesn't increase the risk either in middle-aged and older adults. 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. Researchers from the Boston University School of Medicine 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. It was found that, participants who regularly walked, jogged or otherwise worked up a sweat were at neither greater nor lower risk of developing knee OA. This was true regardless of body weight and type of exercise. Even though exercise didn't ward off knee arthritis, the findings can be seen as good news. 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, 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. 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. Moderate activities like walking and jogging are not risk factors.