Changes

* There are instances of remarkable performances without running long in training. For instance, [http://en.wikipedia.org/wiki/Grete_Waitz Grete Waitz] never ran more than 12 miles in training before winning the 1979 New York Marathon. However, at the time she was a world class track and cross country athlete who trained at 80-90 miles per week<ref name="GreteWaitz"/>. Her book on marathon training emphasizes the importance of the long run<ref name="WaltzBook"/>.

* Most training plans peak at 20 miles, though JD has 22 mile runs and Jeff Galloway has a 26 mile (2 min/mile slower with walking breaks)

* Some coaches recommend limiting the length of the long run to a percentage of the weekly mileage, often in the range 25-35%. The rationale for this unclear, and this recommendation could encourage high levels of [[Training Monotony]].

* Using time rather than distance for long runs is sometimes suggested, as a 16 mile run at 11 min/mile would take a similar time to 22 miles at 8 min/mile. For instance, Jack Daniels does not recommend novice marathoners to do a long run longer than 2.5 hours<ref name="JDArticle"/>. This approach may be based around the belief that runs longer than 2 or 3 hours provide little or no additional benefit<ref name="OverLongRun"/>. While there are some animal studies that show the benefits of endurance training plateaus, these studies looked at a limited aspect of endurance (cytochrome c)<ref name="Terjung-1976"/><ref name="Dudley-1982"/> and other animal studies do not show this plateau<ref name="Powers-1994"/>.

* It is often noted that ultramarathon runners do not train with proportionately long training runs. So a runner training for a 100 mile race will not run 76 mile long runs, which would be the equivalent to a 20 mile run for a marathon. In fact, the great ultrarunner Ray Krolewicz does not do training runs longer than 22 miles<ref name="RayK"/>. However, ultrarunners often run many long runs close together. For instance, Ray has done more than one 22 miler on each day of the weekend<ref name="RayK"/>, and 'back to back' long runs of 20-30 miles are commonly prescribed<ref name="UltraPlans"/>. Also, ultrarunners typically race frequently enough for the races to contribute to their overall training.

* It seems that many runners who run over 24 miles often do so in organized events, even if they are using the event for training rather racing.

=Recommendations=

Here is my personal interpretation of the scientific and anecdotal evidence.