Thanks
@Ned. Hope you enjoyed the trip.
I got the "cumulative fatigue" question from a couple of other people recently as well and how to reconcile that with the traditional suggestion of a 4-6 months build-up. So I have had quite awhile to reflect on these issues...
My thoughts are this: If you really emptied out your gas tank during a marathon, it probably does take most people 2-4 weeks to fully recover. Depending on your background and motivation, your recovery period will either require complete rest or permit you some level of activity, (cross-training or anywhere from 0-100% of your normal training mileage) which will determine if you lose/maintain/gain fitness during this recovery period. I had 4 peak marathons in the last 18 months - 2015 Houston, 2016 Houston, 2016 Hamburg, and 2016 Ottawa, and what I have realized is that I am usually able to run about 50-80% of my peak training volume from the prior training cycle within 2 weeks after the marathon (meaning days 8-14 post marathon). Then I can get in 2-4 workouts at 80-90% of what I would do during an more extended cycle - examples being running 3x2mi at lactate threshold or 10-12 miles at marathon pace when I may normally be running 4x2mi or 13-16 at marathon pace, this seems to strike a good balance between recovery and maintaining fitness, or even gaining a little bit of fitness before a quick taper. I am walking a fine line between recovery/maintenance during these short turnarounds, but definitely erring on the side of recovery, as I believe the fitness has been there since at least mid-March and it doesn't seem to take a lot to maintain fitness.
Looking long-term, I don't think it's wise to race a peak marathon every 5-6 weeks, as I think I would only be giving myself at most 7-10 days in the middle of those cycles to make fitness gains before having to taper again, whereas in an extended 12-18 weeks cycle you are giving yourself at least 2-3 months to make fitness gains. The only reason I am doing what I am doing now, other than having a timeline to follow, is that I think I am already in shape to run the time I need to, so I am not looking for fitness gains. Instead, I just need to make sure I am recovered in between these efforts.
The crazy thing is I am actually feeling much more fresh today than I did at the same point after my last few marathons. I am guessing it's because I didn't get to "empty the tank" as much since my legs failed me and prevented me from putting as much effort into the race aerobically. The hamstring issues also seem to be related to hydration, as I took in a LOT of fluids in the last 24-36 hours right after the race and they feel pretty much normal now. In fact, this may be the best I have felt aerobically/physically 48 hours post marathon.
With all that said, after Gold Coast (and hopefully Rio), I don't think I plan on peaking for another marathon until late fall at the earliest, with early 2017 being a much more likely timeline.