Many people of a certain age avoid high-impact exercise, fearing that the jolts of running and jumping might be hard on aging joints and bones. They may be right, but for those whose bodies can take the hits, high impact exercise may be just what the researchers ordered. Writing in the New York Times, Gretchen Reynolds reports on a recent study that found that “women between 25 and 50 who hopped at least 10 times twice a day, with 30 seconds between each hop, significantly increased their hipbone density after four months.” Reynolds says another group of subjects, who hopped 20 times daily, showed even greater gains. Researchers had already known, according to Reynolds, that high-impact exercise made the bones of adolescents stronger. The dilemma, of course, is determining the risks and rewards of high-impact exercise on aging athletes, whose bones may truly be too brittle to withstand the pounding of running or jumping. The answer, says one expert quoted by Reynolds, is caution. If you’re worried about it, consult a doctor before getting on the basketball court. Read more in the New York Times.