"I have a question regarding your 10% increase every three weeks. How would this work if I were training for a marathon? Would I have to do a 20 mile run five times a week? I'm sure that can't be good for your legs. Do you have another training schedule that you recommend for marathons? Like your friend in the article I have also had IT band problems, which I believe was due to increasing my mileage too fast when training for my second marathon. Thanks for any help you can offer."
In my humble opinion, it takes right on the verge of four years of consistent, (preferably) injury-free training to go from couch-to-marathon. When it comes to the "marathon puzzle," every athlete is an experiment of one.
So, to get from the 20-minute-a-day level to the minimal volume for five-kilometer racing, following a ten-percent progression in time every three weeks it takes about eight months, or 34 weeks. By that time the runner would be running a 60-minute long run and two speed workouts of 55 minutes. The non-speed (track), non-long runs would start at 20 minutes and increase up to 45 minutes.
Should the runner manage to get past the first 52 weeks of running without an overuse injury, often the result of too much (mileage/intensity), too soon (increase), or too wrong (shoe, terrain, surface) they can begin the segue from five-kilometer to ten-kilometer racing. A comfortable and conservative transition can take up to another 52 weeks - a little more here, a little less there. Remember this is just a "run" of the numbers and some of my preferences. The long run for the 10K runner could range from 60-to-70 minutes, with two track workouts of 60 minutes each week. The other runs vary from 55-to-60 minutes.
However, this is where the first "wrinkle" to the plan occurs, a tip of the hat to longer-distance training plans. The volume of every fourth training week is cut back to 65% across the board.
The progression to half-marathon would take another year...up to the third year of injury-free training. The long run during the first six months or so ranges from 60-to-80 minutes, increases to a little over 90 minutes on average for eight weeks, and up to two hours over another 12-week period. Again the volume of every fourth training week is 65 percent of the previous three-week period. Volume, two weeks out from a race, also drops by one-third each week.
The first ten weeks of the fourth year, transitioning from half-marathon to marathon, spends 60-to-90 minutes on the weekly long run during the first ten weeks. The long run ranges from 90-to-120 minutes for 9 weeks, then jumps to 120-to-160min for the 30 week period preparing for a target marathon. There's still two 90-minute speed workouts and 60-to-90 minute "non-speed, non-long" days during the weeks. Once again the volume drops to 65 percent every fourth week, and a two-week, 33-percent pre-event taper.
When it comes to marathon training, and less frequently so when talking about half marathons, the question is not really "How much distance?" but "How much time on the feet?" Naturally, not all training runs, even the ones where the effort is supposed to be at a certain level, are at the same intensity for every run. Many exercise specialists and coaches have all come to the conclusion there is a point of diminishing returns when it comes to the longest distance run, that being 2.5 hours. Many runners feel this compulsion to rehearse the entire marathon distance in training, it is possible to prepare the body for the (additional!) stressors which come beyond 2.5 hours. This is done by running several long runs which approach the 2.5 hour mark (the plan I used as an example had three runs at 2.5 hours).
Why 2.5 hours? Outside of the physiological "tipping-point" after 2.5 hours, marathon training is best described as an exercise in selfishness. Once again, if we look at the assumption of a long run at 20-25% of the weekly training volume, 2.5 hours of running is the 20% point of a training week which encompasses 12 hours, or a 25% point of a 10-hour week. Most family members - especially if they are not runners - might be able to tolerate a couple of months worth of early Sunday mornings (2-to-2.5 hours' worth) without the training marathoner. Some plans would fill the Sundays with anywhere from 2.5 hours to 4.5 hours(!) of training. Looking at some of those plans (published in Noakes' book, "Lore of Running"), I personally would rather be a happy half-marathoner than a miserable marathoner.
So, the best marathon plan is the one which aligns best with the individual athlete's unique physical capabilities (strength, recovery), their lifestyle (time to train) and support structure (family).