Raven Run Nature Sanctuary, located 15 miles south of downtown Lexington, has 734 acres of woodland trails that are terrific for trail running. The 10 miles of marked trails weave through a combination of more open and wooded terrain. The 4-mile ‘Red Trail’ is the signature loop. Combine with the Orange Trail, which winds around a lovely meadow for 1 mile. The terrain in the sanctuary is moderately hilly, and the footing is good.
This link has good information about the area, and a description of the color-coded trail system.