Most readers are probably not actively seeking a reason to start running backwards, but if they did, there are one or two reasons to be found. Gretchen Reynolds writes in the New York Times magazine about research conducted at the University of Milan that found that running backwards, unsurprisingly, used different muscles than those used running forward, required 30 percent more energy, and was much easier on the knees. Reynolds also cites a more recent study involving young women runners; that research found that women who ran backwards for 15 to 45 minutes three times a week for six weeks lost almost 2.5 percent of their body fat. Other research suggests that it improves balance, particularly for older people. Read more from Gretchen Reynolds.