One of the most important aspects of distance running is, well, distance. Without doubt, putting those miles in the bank is the best way to build endurance and to be a better runner. But as central as building mileage may be to your performance, it's also central to causing injury if done carelessly. A few tips can help you build miles safely and to best effect.
The "10 percent rule" is often invoked as the upper limit for safely increasing your weekly mileage week-to-week. But you would do better to be even more conservative than that. Following the 10 percent rule effectively doubles your mileage every eight weeks -- way too much for most runners, certainly for recreational runners. Best to consider a 10 percent increase every two weeks as a firm upper limit, with 5 percent every two weeks being closer to the safe ideal. Conservative and consistent training is all important, and the slower you build your mileage base the better.
While in the base-building phase, smart runners learn to stretch consistently while very gradually adding strength work and mileage, but not necessarily intensity. As you reach 30 to 35 miles per week, level off until you become very comfortable with this amount. Make this your solid base before adding more miles. Except for those few runners lucky enough to be born very biomechanically efficient, most begin to see a breakdown around this point unless they pause to establish a strong foundation. Base training is fundamental to staying healthy and building confidence.
The injury rate becomes much higher once an individual begins to run beyond 40 miles a week. Be very careful about how much mileage you add (and how quickly) as you approach that amount. The mileage should include the long run coupled with one speed session during the week (see our overview of speed workouts for more details). This will lead to consistency and improvement.
Build the long run into your routine every other week. Make the distance anywhere up to 150 percent of your regular midweek runs, and trot along at your normal training pace. If a six mile run is de rigueur during the week, for example, then nine miles should be the upper limit of your long run. You have to build miles gradually and give your body a chance to adjust to the pounding of those extra miles.
As long as you are not picking up your speedwork very suddenly at the same time, you should be able to add a mile or two to your long run every two weeks. This may seem like a painfully slow rate of increase, but it's a lot less painful than the injury you might otherwise risk. Take it slow, it's better than being sidelined for several weeks.
In fact, the most important and often underrated component of a good running program is rest. The body adapts and gets stronger only if you give it a chance to recover after vigorous workouts. All too often, the runner's ego might stop you from listening to common sense, but don't feel that you have to train harder than you really need. As you build mileage, keep in mind that rest and recovery are essential.
This means not only that you should take a rest day after your long run (and you certainly should), but also that you should think in terms of an entire week of rest after high-mileage efforts. Every two or three weeks, indulge your legs with a rest week by cutting down your weekly mileage by 10 or even 20 percent. The next week, you can resume your normal mileage again.
The overall lesson to be learned here is to build miles very, very gradually, with plenty of stretching and plenty of rest.