“Four weeks out is when I do my longest run,” says 2:13 marathoner Keith Dowling. “I’ll run up to 26 miles, with this twist: I do my usual easy long-run pace for most of it, but with eight miles left, I’ll work down to six-minute pace and drop the pace every two miles to finish at five-minute pace.”
Translated into mortal terms: With eight miles to go, begin running one minute per mile slower than your marathon goal pace. Then speed up every two miles to run the last couple of miles at goal pace or slightly faster. This run will teach you how to up your effort as you become tired. Combine this with the half-marathon mentioned above, doing one with four weeks to go, and the other with three weeks to go. Your local race calendar will probably dictate the order in which you’ll run them. But if you have a choice, do the long run four weeks out (for more recovery time) and the half-marathon three weeks before your race.