The week after a marathon, often called the recovery week, is very critical perhaps as much if not more than the week before the marathon. After the completion of a marathon several muscles get stiff and sore specially the hamstring. The time taken for recovery of these muslces varies from runner to runner. In general, it is recommended that the week after a full marathon should be a week of resting with some walking/cross-training towards the end of the week. After the Marathon and Hal Higdon's Post-marathon training guide are two sources of information on training in the period immediate after the marathon.
In my case the recovery after thr RFL Kanakpura run was very quick : I was able to do a comfortable 31 munutes 5K within 48 hours of the run ie on Tuesday. I followed this up with a 8K run on Thursday and a slow 12K run in Cubbon park on Saturday. I guess once you have run several marathons recovery is also much faster. This has definitely been my fastest every recovery. (Apart from the fact that I ran a half marathon at KTM last year within 8 days of doing my personal best full marathon finish at Suntrust Richmond marathon).