A regular long run is necessary if you want to run a marathon, but how far should you go?
Here is an article by Matt Fitzgerald on how to make it easier. Read the original at: http://running.competitor.com/2013/10/training/a-short-cut-to-the-long-run_32317
You can run a good marathon without logging 20-mile training runs.
Most running experts agree that it’s impossible to run a successful marathon without completing some long training runs first. But how long is long? American runners typically aim for 20 miles. Runners on the metric system, however, often peak at 30 kilometers, which is only 18.6 miles. And Keith and Kevin Hanson, coaches of the Hansons-Brooks Distance Project, design marathon training plans for most of the sub-elite runners they coach that regularly culminate in a mere 16-miler—and by all reports they work quite well.
In short, there is no definitive minimum distance that every runner must cover in training before running a marathon. While few runners have the talent to get away with never running more than 13 miles (the longest distance Grete Waitz ran prior to winning the 1978 New York City Marathon) in their marathon preparation, your longest run might not need to be quite as long as you think.
Why? Because, according to some experts, you can largely duplicate the benefits of doing a handful of long runs (think 16-20 miles) by doing a greater number of moderately long runs (think 10-14 miles), some of them at higher intensities. Your best results, however, might come from doing a mix of conventional long runs and long-run alternatives such as the three described below.
“During a marathon build-up, all runners, regardless of ability level, should assure themselves of being able to comfortably run at least 16 miles,” says Kevin Beck, a Boulder-based running coach and editor of Run Strong (Human Kinetics). “That said, there are a number of ways in which shorter long runs may be particularly beneficial.”
The Glycogen Factor
One benefit of substituting some long runs with moderately long runs is that it enables you to increase your total training mileage without risking injury or over training. According to Beck, total weekly mileage is more important than the distance of the long run in marathon training. For example, a program that maxes out with a 70-mile week and a 17-mile long run is likely to render you fitter than a program that does so with a 50-mile week and a 22-mile long run.
The reason has to do with muscle glycogen, the precious fuel whose conservation is vital to marathon success. “The sheer amount of glycogen turnover inherent in high-mileage programs stimulates some of the same physiological adaptations as do long runs,” says Beck. That’s because most of the endurance-boosting benefits of a long run come toward the end, when your muscle glycogen stores are running low. But when you frequently run moderate to moderately long distances, you often start workouts with a half-empty tank.
Another way to get the benefits of 16- to 20-mile runs from 10- to 14-mile runs is to crank up the intensity of those shorter workouts. You can burn as much glycogen in a 90-minute fast run as you can in a two-plus-hour slow run, so you get a similar benefit. Beck recommends running 30 to 50 percent of the mileage in your moderately long runs at your goal marathon pace. You can also increase the intensity of these runs by running on hills instead of speeding up.
Up and Down
Run 10 to 14 miles on the hilliest route in your area. Try to keep your average pace close to your goal marathon pace despite the topography. This workout will not only use as much glycogen as a longer run on flat terrain, but thanks to the downhill portions it will also subject your legs to as much pounding as a longer run, toughening them up for race day.
Warm up with 5 to 10 minutes of easy jogging and then run for 90 minutes at 95 percent effort. So if the farthest you could run in 90 minutes is 10 miles, run about 9.5 miles in your 90-Minute Blast. You will burn as much glycogen as you would in a two-plus-hour run at a moderate pace.
Divided Long Run
Instead of doing a long run on Saturday and taking Sunday off (or vice versa), do moderately long runs on both days. For example, instead of running 20 miles on Saturday and zero on Sunday, run 12 miles on Saturday and 12 again the next morning. The combined benefit of your Divided Long Run will be at least as great as that of the single longer run.
Get There Faster
The best way to combine moderately long runs with traditional long runs in your marathon training depends on many factors, including your experience and fitness levels, your time constraints and your goals. Following is a pair of 10-week schedules of moderately long runs (MLR) and long runs (LR). The schedule on the left is a good fit for runners whose goal is to finish a marathon. The schedule on the right is best for runners who have completed at least one marathon previously and want to improve their time in the next.
Build your long run distance up to 10 miles before starting either schedule. In weeks that contain an MLR and an LR, separate them by at least two days.
Just Finish Plan PR Plan
1 LR: 11 miles MLR: Divided long run 10 miles/10 miles
2 LR: 12 miles MLR: Up and down, 10 miles LR: 14 miles
3 MLR: Up and down, 10 miles MLR: 90-minute blast LR: 15 miles
4 LR: 13 miles MLR: Divided long run 11 miles/11 miles
5 MLR: 90-minute blast MLR: Up and down, 11 miles LR: 16 miles
6 LR: 14 miles MLR: 90-minute blast LR: 17 miles
7 MLR: Divided long run MLR: Divided long run 12 miles/12 miles
10 miles/10 miles
8 LR: 15 miles MLR: Up and down, 12 miles LR: 18 miles
9 MLR: Up and down, 12 miles MLR: 90-minute blast LR: 18 miles
10 LR: 17 miles MLR: Divided long run 13 miles/13 miles