One generalization I am comfortable making is that most people never reach or even approach whatever their personal upper volume limit might prove to be, and this includes people willing to give it a fair shake.

Increases in mileage almost invariably entail increases in run-to-run fatigue as well as a cutting back on racing, a decline in racing performance, or both. What many do not accept is that these effects are transient, and that with patience and prudence, most runners discover that they truly do adapt and reach a new fitness level eventually.

Depending on the magnitude and speed of the buildup, this can take anywhere from weeks to months. Most people simply don’t have the patience for this.

As an infrequent racer by inclination, I was never cowed by going several months in the winter or the summer (the former being mostly off-limits to racing in New England anyway, the latter being a period I generally can’t stand running hard), so it was during these times I experimented with previously unattained volume totals.

The Build-Up

What’s the best way to build up? Many have heard of the 10 percent rule, but I won’t even get into that because it’s interpreted in so many conflicting ways. Instead, I’ll say that if a runner seeks to level out at a given plateau, it is wise to try brief “excursions” into that territory rather than confine yourself to a methodical buildup.

For example, if you’re hoping to get up to averaging an hour a day and are currently at around 30-40 minutes, pick one week in which you hit or closely approach that average, then retreat to the safe familiarity of your usual workload for a couple of weeks. Then repeat the excursion. If this works, begin a more stepwise build-up, always cutting back to pre-build-up baseline one every three weeks, every four at most. In fact, be prepared to implement such cut-back weeks into your training as a matter of course, and to mix up your mileage totals in general (as Pete Pfitzinger touches on in Road Racing for Serious Runners, “training monotony,” while simplifying things marvelously for people, has proven the bane of many a distance runner).

The advantage in doing things this way is psychological: it eliminates the fear and uncertainty of the goal mileage total right off the bat. Someone who’s running a steady 30 miles a week and has settled on 50 miles a week as a goal six months out can certainly build gradually toward that load, reaching it for the first time in 180 or so days, but logging a lone 50-mile week early in the build-up can be a supreme confidence booster.

I should hasten to point out that mileage totals should never be “goals” in and of themselves; the idea is to bolster one’s training in order to ultimately race faster. But people need guidelines to follow, and most would rather work toward some pre-defined workload rather than completely wing it. Again, you can follow a published plan, plumb the wisdom of experienced running friends, or enlist a coach to help you along during the build-up process.

Volume & Intensity Control

What about two-a-days? Some believe that running once a day until it is no longer prudent is the way to go. This threshold generally lies at around 70 or 80 miles a week. I, however, believe that if someone is eventually going to be running the sort of mileage that requires some two-a-days, it is better to experiment with these before they become necessary.

So even if you’re comfortable running 50 or 60 miles a week using singles and are planning to reach 90, you would be well advised to try running twice a day a couple of times a week even at more modest totals. There’s also an argument for splitting longer days into two sessions frequently because many injuries seem to occur after runners have been on their feet for a long time, rendering day after day of longer single runs risky. I have no data to support this, but I tend to believe it.

What about intensity? During a mileage build-up, something usually has to give, so you should eschew most speedwork and take care to keep the pace modest on most days. Harder running is not strictly verboten, but recognize that your recoverability will take a temporary hit as your increase your workload, since easy days are no longer as easy as they were previously.

Run Smarter

Finally, a word of caution. Beware of the insidious tendency to run mileage for mileage’s own sake. If you’re a durable runner with ample time on your hands, you run the risk of falling into a “volume trap.”

Dedication and hardiness combine to form a double-edged sword: The same qualities that will allow you to train and race at very close to your maximum potential can also lead to romancing the training log, with an attendant reluctance to take cut-back weeks and balance off the mileage with the workouts necessary for quality racing.

Experience is really the only thing that allows runners to distinguish between the transient tiredness that accompanies any mileage buildup and the chronic staleness of an overtraining-type syndrome. And if there’s one word that applies more than any other to this chapter, it is “experience.” Pithy as it sounds, only you can ultimately determine your ideal workload range at any time. The trick—and it doesn’t come easy to driven athletic types—is being honest with yourself.

Of course, workload is only one aspect of training. Performance, not training itself, is the target, and it’s easy to forget that as you plunge deep into the territory of exploring your personal limits. Don’t let yourself become one of the forgetters.