Last long run before marathon?

When do people do their last bruising run before the marathon? I've always stuck to 2 weeks before but was considering dropping it back to 4 weeks before and knocking out another half marathon to up the fitness. Just an idea, wondered what others do.

I usually do mine 3 weeks before.

  Not sure if running a very hard race just before a marathon is advisable.

Just to add a couple of points.....but I guess that it really depends on the sort of schedule you've being doing.

I ran the GNR two weeks before Leicester Marathon. I was following a 12 week, 70 mpw schdule which had me down for a 17 mile run 2 weeks before the marathon but I ran the GNR instead. I used the GNR as a 12 mile tempo run (slow 1st mile) and then raced the last 12, running the last mile just over 6 minutes. Finished in 1.32.28.

Ran Leicester Marathon 2 weeks later in 3.09.20 (PB by over 10 minutes). I did feel rather lethargic and sluggsih during the 2 runs but may have been due to the taper anyway.

Normal rule of thumb is to decrease the milage but retain the general intensity of your current sessions. Also, they say that you need a days recovery for every mile raced, so you may get away with racing a half 2 weeks before a full. The choice is yours!

Good luck.