First, the bad news. An academic review of 23 seemingly authoritative studies of back pain relief found that most of them, which involved education or orthotics, did almost nothing to reduce the likelihood of another bout of pain. But as Gretchen Reynolds reports in the New York Times, exercise did do some good. In fact, it did quite a bit of good. Reynolds reports that the researchers found that exercise combined with education reduced the risk of another episode of back pain within the next year by 45 percent. Surprisingly, the type of exercise didn’t make much difference. Reynolds reports that some exercises were designed to strengthen core muscles and others combined aerobic conditioning with strength and balance training. And now back to the bad news: the protective effects of exercise appeared to evaporate after one year, perhaps, the researchers say, because people stopped exercising.