I consider total mileage to be an element of quality in a marathon program.  As a general rule of thumb, I think that marathoners should strive to reach peak weeks of at least 50+ miles/week in order to run good, hard marathons.  Of course, a program should start at a lower level and build to a few peak weeks.

 

Some runners, including some experienced and capable marathoners, can't reach that level without breaking down and suffering injuries.  Novices are probably well advised to start conservatively with peak weeks in the 35-45 mile range, which is the level that I consider a minimum for marathoning, until they learn how much they can handle.  Of course, they should also stay a little on the conservative side in the race itself on that mileage and run a bit slower than that predicted by shorter race distances, since their endurance base is minimal.  As they gain marathon experience, they can step up the training mileage....and increase the race intensity.

 

More important than peak weekly mileage is total mileage in a training program.  For instance, running a peak week of 60 miles is meaningless if all other weeks are less than 50 miles.  A 16-week program that totals 800 miles, which might start at 35-40 miles/week and peak at 60-70 miles, will prepare you better than one of 500 miles, which might start at 20-25 miles/week and not go above 40 miles.  As when training for any endurance sport, however, novices should start on the conservative side and build their training workload over several training cycles.

 

I started with peak weeks at the 45 mile level in preparing for my first 3 marathons.....but I didn't stay on the conservative side in the races, so I suffered cramps.  I increased that to 50-55 miles/week for the next few marathons, then reached 60-70 miles/week for all the rest of my 21 marathons.  As my mileage increased, I was stronger going into the marathon and ran more controlled races, especially in the last 6-10 miles.

 

Jim2