Regular running slows the effects of aging, according to a new study from Stanford University School of Medicine that has tracked 500 older runners for more than 20 years. Elderly runners have fewer disabilities, a longer span of active life and are half as likely as aging nonrunners to die early deaths, the research found. "The study has a very pro-exercise message," said James Fries, MD, an emeritus professor of medicine at the medical school and the study's senior author.