Don't let arthritis keep you down.That's the big message coming out of research conducted at Northwestern University, were scientists followed 5,715 men and women with arthritis, ages 65 and older, over a two-year period. The Tufts Health & Nutrition Letter reports that almost two-thirds of the subjects did not get “vigorous†exercise at least three days a week. Those who did exercise had only half the risk of functional decline as their more sedentary peers. Overall, about 14 percent of the subjects who had no serious physical limitations when the study began experienced a decline in function over the two-year span.