In 2001, now I don't remember, one Italian athlete, Giorgio Calcaterra, ran 13 marathons during 14 following weeks, all in times between 2:13 and 2:20. In some day, when I'm back Italy from China, I can give the details of all his marathons.
He was a taxi driver, and, during that period, his weekly plan was as follows :
Monday : Rest
Tuesday : 40' easy
Wednesday : 1 hr easy
Thursday : 20' easy + 40' with short variations of speed (fartlek)
Friday : Rest
Saturady : 30' easy
SUNDAY : MARATHON
At that time, we had problems to select the Italian Team for the Marathon World Cup. So, I asked him to look for preparing, once in his life, ONE Marathon in proper way.
He answered me : "How much do you think I can run preparing in the best way only one Marathon ? 2:12, 2:11, because of sure I can't run faster than this. If I run 2:11, what can change in my life ? In any case, not enough for earning money, and not enough for having great satisfacions.
I like running, and this is my motivation. I am lucky that my body never got injured, and running in this way, I don't face any mental pressure. Why have I to change ?".
In the last 3-4 years, Giorgio Calcaterra became 2 times World Champion of 100 km, and never lost one race on the longest distance.
The problem to recover after a Marathon is 90% mental.
When an athlete is able running a Marathon very fast, his body is not hurted, because the question is : WHY WAS HE ABLE RUNNING SO FAST ? and the answer is : BECAUSE THE CONDITIONS WERE PERFECT.
When there are perfect conditions (temperature between 8° and 15° C, dry weather, no wind, flat course, even pace) an athlete doesn't lose too many mineral salts, and is able to preserve a good hydrosaline balance. He doesn't hurt his body, simply becomes empty at the end of the race, but doesn't provoke any damage his muscle fibers.
So, his only problem after the race is to REFUEL, and this is possible in 3 days with proper assumption of carbohydrates.
This can happen also at the highest levels. Moses Mosop, one week after running in Boston 2:03:06, was already in full training, 30 days later ran the best track session of his life, at 2400m of altitude, on a very dirty track in Kamarin (Iten), with 18 times 1000m (recovery 1'20"), the first in 2'45", 16 times in 2'42" andthe last in 2'36", and 13 days later destroyed the WR of 30000m in Eugene running 1:26:47.
Instead, when the winning time in a great Marathon is very slow (for example, WCh in Osaka 2007, or Boston last year, when Geoffrey Mutai dropped out), is because there is some reason which not allow runners to run fast, mainly high temperature (higher than 30° C) and high humidity.
In these conditions, after 20 km the athletes already lose more salts and more water than after the full Marathon in perfect conditions, and, for finishing the race, they need to find resources consuming the fatty acis in their cells membranes, provoking damageous to their muscle fibers which require very long time for returning at the previous level. I remember, in 1993, one my athlete finishing a Marathon with CK at 18,000 : she couldn't start running again for longer than 3 months.
In this case, the problem is not they finish the fuel, but they need to rebuild a part of their structure. In this case, aminoacids can have a great role in accelerating the solution, being like bricks for building a house.
Of course, when you finish a Marathon in that terrible conditions, you are affected mentally, too.
But, when everything is ok, it's possible to recover in very short time from a very fast Marathon.
If top african athletes don't use to run a REAL marathon at 97% of the max value, 4-5 weeks before the targetted Marathon, is not because this could not be a good technical option, but because there are problems of management : when you sign a contract for 100,000 - 300,000 USD for starting (appearance), you sign that you can't run any Marathon during the period included between two months BEFORE and two months AFTER the Marathon (that pays you, in any case, 50% of the appearance also if you drop out).
That's a reason because nobody, among the top runners, goes to run Dubai, also if is the fastest course, and is also the reason because, OF SURE, Kenenisa Bekele DOESN'T DEBUT IN DUBAI (there is no appearance).