 The second U.S. masters nationals, July 3–6, 1969, drew 200 athletes and introduced 10-year age groups for all events.Inspired by these first nationals, participants founded their own masters meets across the United States and into Canada.Also helping light a fire under sedentary seniors was retired Air Force Maj. Kenneth H. Cooper, a physician whose 1968 book "Aerobics" created a running craze.