Is it better to bike or run? Gretchen Reynolds asks that question in an Ask Well column in the New York Times, and she turns for an answer to Hirofumi Tanaka, a professor of kinesiology and director of the Cardiovascular Aging Research Laboratory at the University of Texas at Austin. They’re both good, says Tanaka. Running does burn calories faster, but not that much faster. The American College of Sports Medicine estimates that someone weighing 150 pounds who runs at a brisk seven minutes per mile will use about 1,000 calories per hour, and the same person pedaling at a steady 16 to 19 miles per hour will burn about 850 calories. Walking, on the other hand burns only about 360 per hour at a four-mile-per-hour pace. When risk of injury is thrown in the mix, the decision gets murkier. Tanaka says runners are more likely to get hurt than bikers, although biking can certainly result in sore muscles. So what’s a person to do? Tanaka suggests biking one day and running the next. Or, do whatever you want to do, just do something.