How Long Runs Can Help You Get Faster

What if we told you the secret to getting speedy wasn’t solely about adding short track workouts to your schedule and becoming a pro at tempo runs?

No, what runners often miss when they feel it’s time to up their pace is that faster times often come from dedication to 1) logging longer long runs and 2) upping your weekly mileage. Indeed, if you’re setting a more aggressive time goal—whether you want to run your fastest mile ever or want to break two hours in the half marathon with the help of a quicker average pace that you can hold—you need more mileage.

One easy way to do that: up that weekly long run.

But how does running longer translate to running faster? There are quite a few physical perks of running longer. Let’s take a deep dive into the benefits.

1. Enhanced Oxygen Delivery to Your Muscles

Long runs build denser capillary networks throughout your body over time, says Jason Fitzgerald, USATF-certified run coach and founder of Strength Running. Capillaries are responsible for exchanging oxygen, nutrients, and waste products between your blood and muscle tissue. The increased blood flow you get from a regular extended run (not just your typical short easy day) signals to the body to form new blood vessels.

“This means oxygen can move faster and more efficiently throughout your body—especially to the extremities like your legs—which are rich in blood capillaries,” says physical therapist and running coach Emmi Aguillard, D.P.T. “This allows the exercising muscles to receive the oxygen they need and improve the body’s ability to quickly return blood back to the heart to get reoxygenated.”

Oxygen is used to power our cells, muscles, tissues, and brain, all of which are necessary for not only daily functioning, but running your best, too. So when it comes time to run faster and hold a higher pace, that stronger oxygen-delivering system allows you to keep going without fatiguing as quickly.

2. Optimal Fuel Utilization

Long runs and more training volume make your body’s mitochondria—often called the “powerhouse of the cells,” they help you create the energy your body needs while doing aerobic running—more efficient by increasing their size and density, says Aguillard.

Similar to having a robust capillary system, stronger mitochondria means we can produce energy more efficiently. Aguillard explains. “We can also get more efficient at burning fat for energy—a.k.a. fuel—which allows us to spare our glycogen storages for speedwork,” she says.

The more efficient your body becomes via long runs on using fat as fuel instead of your glycogen/carb stores, the longer you can run with less fatigue during harder workouts.

3. Stronger Foundation

Consistently doing long runs builds stronger leg muscles, connective tissues, bones, and crucial respiratory muscles like the diaphragm and core, according to both Fitzgerald and Aguillard.

“Stronger tendons and bones allow your body to handle both the higher volume and higher intensity of training with decreased risk of injury,” Aguillard says. “If you can train harder and faster, you’ll get faster and improve performance.”

Keep in mind if you’re newer to logging 60-90 minutes of running in one go, you’ll be like most runners where your form and stride fatigues toward the end. That’s natural. “Running more often, for longer, helps your body find its most efficient form,” Fitzgerald says. Over time your running mechanics and stride efficiency will improve through repetition.

Another thing that will improve is your overall running economy, which is the amount of oxygen you utilize to run at a certain pace. (Learn more about the nuances of running economy with this detailed guide.)

The most important advantage you gain from your long run is aerobic endurance. Your body is learning to use your lungs and heart more efficiently for any run on the schedule. And all these gains come without putting a huge stress on your body (outside of some extra time on feet).

“With long runs you’re still reaping the cellular-level benefits—capillary refill, mitochondrial adaptations—without putting stress on the system that can impede recovery, which is when the body is healing from the last tough workout and reaping the performance gains,” Aguillard says.

One thing to make this the most useful is reminding yourself that most long runs should be done at a zone 2, or conversational pace. You don’t want to go too hard on these workouts every week.

Why? You’re not truly obtaining any recovery impacts from a long run if you do those runs at a slightly lower effort than the days you have a speed workout on the schedule. A few hours after a typical long run, you should feel like there is a lot left in the gas tank to accomplish other runs throughout your week that further help with speed development—intervals, hill repeats, and other runs above zone 2. You want the ability to hit the paces you need to see improvement in speed.

Slower pacing on long runs also teaches you how to hone in on mental fortitude—not giving up when the going gets tough.

Science backs this up: According to a 2024 review in EXCLI Journal, “mental toughness is considered one of the most important psychological components of athletic success, as it helps athletes boost self-confidence.” And, a small 2023 study in Perceptual and Motor Skills suggests being strong mentally is positively correlated with better performance outcomes in trail runners.

Just how long should your long run be? Some say to double the length of your “normal run,” while others suggest striving for 20 to 25 percent of your total weekly mileage. This means if you typically run 30 miles per week, 7 and a half of those miles should be completed during your long run.

But remember: When thinking about setting weekly mileage goals, it really isn’t about your one weekly long run, but more the cumulative mileage you’re running, Aguillard explains.

“More frequent running, and therefore more cumulative mileage, would allow for more metabolic adaptations for the runner, which would lead to increased running economy,” Aguillard says.

It’s worth mentioning, there is a point of diminishing returns with mileage, Fitzgerald says, “though most recreational runners will never reach that point since most never try to run as much as they can physically tolerate.” Elite runners, who find their personal limit typically around 90 to 120 miles per week, are most likely to reach this point, Fitzgerald explains.

But most runners will find that their personal mileage limit is when they keep getting running injuries. To eliminate the potential for getting hurt, you’ll want to gradually increase your weekly mileage over time. “Mileage can increase by about 10 to 20 percent from peak mileage to peak mileage season to season,” Fitzgerald says.

Most experts suggest gradually increasing your long run to reach the following peak distances for each goal race:

• 5K: 5 to 6 miles for beginners; 10 to 12 miles for intermediate/advanced
• 8K/10K: 6 to 10 miles for beginners; 12 to 14 for intermediate/advanced
• Half marathon: 12 to 13 for beginners; 16 to 18 for intermediate/advanced
• Marathon: 18 to 22 for beginners; 18 to 30 for intermediate/advanced

Danielle Zickl

Freelance Writer

Danielle Zickl is a freelance writer who has 10 years of experience covering fitness, health, and nutrition. She's a graduate of Ithaca College. You can find her work here on Women's Health, and in many other publications including PS, SELF, Well+Good, Runner’s World, Outside RUN, Peloton, Men’s Fitness, and more.