Increasing Mileage Too Quickly Is the Fastest Ticket to Injury Town—Follow These 6 Rules to Add Miles Safely (2024)

If you’re hesitant to increase your mileage running in the summer because of the heat, that’s understandable. But with proper planning, summer running can be a great time to tack on miles to prepare you for fall races.

Plus, the benefits of running higher mileage are clear: Building up your mileage (to a point) forces your body to adapt on its physiological, biochemical, and molecular levels, which in turn makes you a much more efficient and faster runner. Hello, new PR.

The caveat: As anyone who’s suffered an overuse injury knows, there’s a right and wrong way to build mileage. Here, Runner’s World asks run coaches to share a few tips for how to increase mileage safely this summer.

1. Follow the 10- to 15-Percent Rule

Many overuse injuries happen because runners increase mileage too quickly, Stephen Furst, a former All-American runner at North Carolina State University and assistant for the NC State track and cross-country programs tells Runner’s World. New runners who ramp up volume too fast are especially vulnerable to injuries, because their bones, tendons, ligaments, and muscles haven’t yet been conditioned to withstand the impact of running. But even seasoned runners can get hurt from building too quickly.

“I’ve seen runners who used to do 100 miles per week get hurt while they are only at 60 per week, because they built up incorrectly,” Furst says. “Just because you used to do a certain amount of miles doesn’t mean you can pick up right where you left off.”

That said, runners who have run higher mileage in the past can usually increase their mileage more rapidly than those who haven’t, because their bodies have already adapted to high-volume training at one time, Furst explains.

Regardless of your previous experience with mileage, all runners should follow the general 10- to 15-percent rule: Calculate what 10 to 15 percent of your weekly mileage is, then increase your mileage each week by no more than that amount. For example, if you usually run 10 miles per week, increase by no more than 1 to 1.5 miles the following week.

Research backs this up, saying that those who increase mileage too fast have a higher risk of injury compared to those who do so gradually.

2. Build for 3 Weeks, Rest for a Week

Another key to building mileage safely is to give your body a “down week.” In the same way that you shouldn’t run hard every day, you shouldn’t try to up your mileage every week. Furst recommends increasing mileage for three weeks, and then taking the fourth week “down,” by running a lower weekly mileage and more easier runs than the week before. (You’ll see this built into most Runner’s World+ training plans.)

For example, if you aim to run 60-mile weeks, you may run weeks of 40 miles, 46 miles, and 52 miles, and then drop back down to 46 miles in the fourth week. This relative resting period gives your legs time to absorb the mileage and build critical muscle memory before tacking on more miles. Plus, they have time to recovery so you can get back out there for more miles without overdoing it.

“Developing and maintaining consistency in your running is really important,” Furst says. “Any type of change on the body—including mileage—is really stressful, which is why so many injuries happen during buildup phases. Once your body is comfortable in a certain mileage, it is very easy to keep doing that week after week.”

3. Increase Your Long Run Gradually, Too

Because many recreational runners who are training for marathons do the bulk of their weekly mileage in a weekly long run, it can be tempting to increase mileage by simply ramping up long runs. But this method can be especially hazardous, since extending time on your feet while you’re already tired can result in sloppy form and leave you more prone to injuries.

Furst recommends that runners increase long runs by 10- to 15-percent each week, with a down week every fourth week, in the same way that you increase your overall mileage. For the runner who is building to 60-mile weeks with a peak long run of 20 miles, the four-week pattern could look like this:

• 40 miles (10-mile long run)
• 46 miles (12-mile long run)
• 52 miles (14-mile long run)
• 46 miles (12-mile long run)

4. Take It Easy

While you’re building mileage, your focus should be on completing the distance, not hitting a certain pace. A common mistake runners make is increasing both volume and intensity at the same time, which can lead to overuse injuries or burnout, Furst says.

Speed workouts are especially ill-advised while running in the heat, because your body is already working harder to maintain a given pace. Leave intense intervals for later in your training and try to schedule those intense workouts for a cooler day, the early morning, or on a treadmill.

5. Prioritize Fueling and Recovery

Hands down, the best way to successfully build mileage is to recover well. “In my experience, runners usually aren’t overtrained, but under-recovered. A lot of runners blame their failure on being overtrained when really they just had a bad day,” Furst said.

While most runners think of recovery as what immediately happens after a workout—cooling down, stretching, and foam rolling—it involves much more than that. Getting a proper amount of sleep, eating the right foods and enough of them, strength training regularly, practicing mindfulness, and eliminating extra stress are all necessary components of recovery.

Sleep and fueling enormously affect athletes’ training performance, Furst says. Runners often misinterpret signs of sleep deprivation as training fatigue, which can lead to running less when you really just need more sleep.

Fueling properly is important for any training cycle, but it’s especially critical when you’re increasing mileage, because you have to consume more calories to keep up with the extra energy you’re burning each week.

For runners, eating more—especially carbs like grains and produce, as well as healthy proteins and fats—is often better than eating less, because it ensures that your body has plenty of energy and nutrients to rebuild bones and muscles.

6. Look Out for Injury Warning Signs

Even if you do everything right while building mileage, injuries sometimes happen. That’s just the nature of our high-impact sport. While overtraining is unlikely to happen if you increase volume slowly and prioritize recovery, if you feel extremely fatigued while running for seven days in a row, you should probably take a few days off, Furst says.

Continuing to run on exhausted or achy legs can make you more at risk for developing overuse injuries. If you do develop an injury that changes the way you run and alters your gait mechanics, you should have it checked out by a doctor.