You’ll find countless approaches to increasing your run mileage and building endurance for long-distance races. And there’s no one-size-fits-all way to go about it, but one strategy that seems to be as old as the modern running movement itself is the “10 percent rule.”
It’s exactly what it sounds like: “The rule states that to stay injury-free in training, you should never increase your mileage by more than 10 percent in any given week,” Jeff Gaudette, owner and head coach at RunnersConnect tells Runner’s World. “The thought behind it is that this incremental increase is gradual enough to allow the body to adapt to the workload safely.”
Because it’s so simple and easy to follow, the 10 percent rule has been a go-to for scores of runners over decades. But is this rule past its prime—and should it really be considered a “rule” at all? Here is the history of 10 percent rule, its benefits and drawbacks, and strategies to use instead to increase your weekly mileage and improve your run performance.
Should you follow the 10 percent rule?
One of the first proponents of the 10 percent rule was Joan Ullyot, a physician and early advocate of women running long distances, who wrote Women’s Running in 1976. Taking note of how frequently runners got injured when they increased their training load too quickly, Ullyot, along with Joe Henderson—the original editor of Runner’s World—spread the 10 percent gospel in the 1980s.
“I suspect it became so popular for a few reasons,” says Gaudette. “It’s an easy thing to follow; it gives a specific number and makes it easy to universally apply; and on the surface, increasing mileage by no more than 10 percent seems gradual enough.”
Despite its popularity, the rule has been a mixed bag when put to the test—and it actually hasn’t been put to that much scientific testing in the first place. For example, in a 2008 study, Dutch researchers looked at runners who were training for a four-mile race, and found that 20.8 percent of runners who increased their mileage by 10 percent weekly over 13 weeks experienced an injury. Meanwhile, 20.3 percent of runners who increased their mileage by 50 percent for eight weeks got injured. In other words, about one in five runners got injured regardless of how quickly they added mileage.
More recently, runners who exceeded the 10 percent rule while training for the New York City Marathon did not experience more injuries than those who stuck to the rule, according to a 2022 study published in the British Journal of Sports Medicine.
However, runners who increased their mileage too quickly—measured by another standard—did have higher rates of injury. Using a metric called “acute-to-chronic workload ratio” (ACWR), the researchers found that if ACWR was greater than 1.5, they were at a higher risk of injury. ACWR compares how much training (workload) a person does in a short amount of time (acute) to their training over a longer period (chronic).
That said, over the decades, many runners have made the 10 percent rule work for them. Here’s what to know about the benefits you can gain from following the rule, and the drawbacks of doing so.
What are the benefits of the 10 percent rule?
The 10 percent rule of running is easy to follow and doesn’t require a complicated plan or complicated math. “While I think there are better approaches, it’s a really simple way to guide someone on how they can increase mileage fairly safely,” says Gaudette. “This can be very helpful when you’re working with someone who doesn’t want to get into the weeds of training and just wants a simple plan to follow.”
The rule hasn’t been shown to be ineffective or dangerous, so if you need an easy way to increase mileage, it’s not a bad way to go. And because increasing volume too quickly has been link to common running injuries, including IT band syndrome and shin splints, it’s still important to maintain a gradual build.
Are there reasons not to follow the 10 percent rule?
If you’re a novice runner prepping for your first marathon, building up your mileage could feel like it takes forever. “For beginners starting at 10 to 15 miles per week, it will take quite a few months to get to 25 or 30 miles per week,” notes Gaudette. On the flip side, if you’re quite experienced and regularly clock 70 or 80 miles per week, tacking on another 7 or 8 miles weekly can be a too-aggressive jump. For these reasons, the 10 percent rule may not be right for you.
Another drawback of the rule is that it only cares about mileage—not the types of sessions you’re running. “If you’re thinking of following the rule, ask yourself if you’ll also be taking into consideration any increases in intensity, races, or harder workouts,” Dave Berdan, two-time winner of the Baltimore Marathon, former collegiate coach, and current coach with Run Doyen tells Runner’s World. “Everything needs to be monitored, not just overall volume. Volume at all of the different training intensities matters more than random overall volume.”
What to Keep in Mind When You Increase Mileage
If you set the goal to run more miles, you can always follow a training plan to reach a certain distance, such as a half or full marathon. Most of those plans incorporate gradual increases in distance, with other workouts, to help you go longer. But if you’re going to sidestep the 10 percent rule, here are some guidelines to keep in mind.
Have Regular Cutback Weeks
Gaudette prefers to follow a three-weeks-up, one-week-down training plan: Increase your mileage slowly over three weeks (making sure to keep a rest day or two mixed in each week), then a step back during the fourth week and cut your mileage total back to the same number as week one. The cutback week gives your body a cushion to rest and recover.
Enlist a Coach
There are a variety of ways, some more inexpensive than others, to ask a coach to help you figure out how many miles you can safely add to your schedule based on your experience and goals. Berdan connects with his clients to assess how their body is handling both the volume and intensity after each week. “It’s through regular communication about how they are responding to workouts that I plan increases or decreases in volume,” he says.
Dial Down Your Intensity
Permission to take it a little easier with speed work when you bump up your weekly miles. For instance, if you’ve been doing two speed days per week, cut back to one. If you’ve been doing one, decrease the volume by 25 to 50 percent, suggests Gaudette. “Reducing the intensity has been shown in some studies to really help with adaptation to increasing mileage,” he says. You can swap these speed sessions for easier, zone 2 runs.
Check In With Yourself
Throughout training, keep tabs on your mileage, intensity, and how you feel, suggests Berdan. Keep in mind other stressors in your life that might affect how much volume you can handle. “Everyone has good runs and bad runs, and it’s normal to be sore sometimes when pushing limits on volume and intensity—but if you’re chronically sore or have several bad days per week, that’s a good sign you’re doing too much,” he says. “To find your training volume sweet spot, the most important thing is listening to your body.”
Laurel Leicht
Laurel Leicht is a writer and editor in Brooklyn. She's covered health, fitness, and travel for outlets including Well+Good, Glamour, and O, The Oprah Magazine.
