You probably already know that running is a stellar form of exercise. It provides a host of health-boosting benefits, including improved heart function, boosted mood, and reduced risk of a bunch of chronic diseases.
But if you’re looking to maximize these gains, what’s the better pick: fast running or slow running?
On the one hand, fast running may seem like a smart way to bolster the efficiency of your sessions, allowing you to burn more energy and log more miles in less time. That said, slow running aligns with the zone 2 cardio trend, which promises ample cardiovascular benefit, plus minimized injury risk. So it is a toss-up? Or does one reign supreme?
To settle the debate, we tapped two running coaches. Read on to learn what distinguishes fast running from slow running, the unique benefits of each, and the ideal breakdown within a training program, depending on your goals.
What do we mean by “fast running” and “slow running”?
“Fast” and “slow” are subjective terms. What may be considered fast for a beginner runner–for example, a 10-minute per mile pace–would likely qualify as super slow for an Olympian, whose fast may be, say, a five-minute per mile pace.
So instead of assigning universal paces, a better way to think about the distinction is how easily you can hold a conversation as you stride. With slow running, your effort level should be low enough that you can talk no problem, Matt Campbell, a certified personal trainer and run coach at PRO Club / Bay Club in Washington state, tells SELF. “You’re not out of breath,” he explains.
For beginner runners, this often means taking regular walk breaks to ensure you maintain that ability to chat, Campbell says. Another way to think about it: At the end of a slow run, you should feel like you could have kept going, exercise physiologist and running coach Janet Hamilton, founder of Running Strong in Georgia, tells SELF. Slow running, she adds, should feel comfortable and easy.
If you’re someone who tracks heart rate during exercise, slow running typically falls into zone 2, which means your heart is beating at about 60% to 70% of its maximum rate, Campbell says.
On the flip side, fast running is pretty much the opposite of slow running. With fast running, talking is…not really an option, Campbell says. The run itself should feel hard and uncomfortable, and your heart rate will likely be 75% to 90% (or possibly more) of your maximum, Campbell says. This translates to zones 3, 4, and 5. No matter your fitness level, fast running will likely leave you feeling gassed.
The benefits of slow running
Slow running can get a bad rap, in part because of the pervasive “no pain, no gain” mentality in the fitness world. “People just don’t understand that it’s okay to run at an easy, conversational pace, and you are going to get some physiological benefit from that,” Hamilton says. In fact, the “laundry list” of benefits you can reap from slow running is “extensive,” she says.
For starters, slow running stimulates your body to make more mitochondria—the little organelles in your cells that create the energy that fuels your movements–and also spurs your existing mitochondria to grow bigger, Hamilton says. These mitochondrial gains help you both exercise and complete tasks of daily life with less stress to your heart, lungs, and muscles, as SELF previously reported. Slow running also increases the size and strength of your heart chambers, increases blood volume, and improves the strength of your connective tissues, tendons, and bones, Hamilton adds. In other words, it bolsters the functioning of your cardiovascular and musculoskeletal systems.
To be clear, you get these benefits from fast running, too, but one thing unique to slow running is that it delivers these gains with a lower risk of injury. Compared to fast running, slow running delivers less stress to your joints, tendons, ligaments, and bones, which means these structures are less injury-prone. Simply put, “you’re not taxing the body as hard,” Campbell says. And that usually allows you to recover faster from your workouts, which helps you train more consistently and log more miles per week, he explains.
This is why many half-marathon and marathon training plans heavily bias slow running. When you’re training for those distances, you need to tackle a high volume of running each week (anywhere from 20 to 50-plus miles) to prepare your body for race day. And logging the vast majority of those runs at a slow pace is a smarter, safer way to achieve that.
The benefits of fast running
Fast running delivers many of the cardiovascular and musculoskeletal benefits you’d get from slow running. But one of the unique benefits is that it recruits your
fast-twitch muscle fibers, which produce more force than your slow-twitch fibers do, Hamilton explains. (Slow running, as the name suggests, primarily recruits your slow-twitch fibers.) By bolstering your fast-twitch fibers, you can improve your overall power, speed, and strength.
Fast running also works your anaerobic system, which is what fuels your body during intense bouts of exercise. Doing more anaerobic training helps you maintain faster paces for longer, which means it can bolster your chances of nabbing a PR in your next race.
Fast running is also great for boosting your VO2 max (a measure of how efficiently your body uses oxygen during exercise), Campbell says. VO2 max is widely considered the best indicator of your cardio fitness–the higher your VO2 max, the fitter you are—and a high VO2 max is also linked with positive health outcomes, including reduced risk of cancer, heart disease, and early death. So any gain in VO2 max is a win.
Then there’s the fact that fast running provides a great chance to dial in your form. When you run fast, certain form errors that you may not notice with slow running—such as swinging your arms across your body (versus forward and back), or shrugging your shoulders up towards your ears (instead of pulling them down and back)—can become more exaggerated and obvious, Campbell says. With the help of a coach, running buddy, or general body awareness, you may be able to pinpoint these form mistakes when you’re running fast and then work on correcting them across all of your running paces.
Lastly, fast running is helpful mentally if you’re training for a race that involves fast running (as most races, by definition, do). By practicing running at race pace before competition, “you’ll just become more comfortable with it, and you’ll know to expect in your actual race,” Campbell says. And that can help you arrive at the starting line feeling confident and prepared.
The ideal breakdown of fast versus slow running, depending on your goals
Now that we know the benefits of fast versus slowing running, let’s circle back to the original question: Which one is best?
The answer really depends on your reason for running in the first place. If you’re lacing up to reduce your risk of chronic diseases, and/or attain or maintain basic fitness, then slow running is your better bet, Hamilton says. That’s because “there’s really no compelling reason to push your limits in terms of training pace, unless you’ve got a specific goal in mind,” she says. You’ll gain plenty of health-boosting benefits from slow running, especially if you do it consistently. And “the best way to train consistently is to be injury-free,” Hamilton says.
Now, if you have a more specific goal with running—say, to run a 5K as fast as possible or to crush your next half marathon—there’s plenty of reason to incorporate fast running into your routine. That’s because fast running will push your fitness up a notch in a way slow running simply won’t, Hamilton says. The catch, though, is that incorporating more fast running into your routine raises your injury risk, so it’s important to be smart about how much of it you mix in.
As with many things in fitness (and life), there’s no one-size-fits-all formula here for the ideal mix of fast versus slow running. “It really varies based on the person’s fitness history, injury history, their training goals, and their ability to train consistently,” Hamilton says. That said, the clear majority of your training–definitely greater than 50%–should be done at a slow pace, Hamilton says. This is true even if you’re training for a fast race, like the mile or 5K, she says.
That said, folks training for those shorter, faster races will likely want to do more fast running than people gearing up for longer distances, like a half or full marathon, Hamilton says.
A common guideline with marathon training is to run 80% of your weekly miles at a slow pace, and the other 20% at a fast pace, Campbell says. More experienced runners, he says, sometimes do a split of 70% slow and 30% fast. “Either of those is easy to remember and from what I’ve seen, works pretty well,” he says…as long as you actually adopt a slow pace on your easy runs, which a lot of people struggle to do, Campbell adds.
Indeed, Hamilton says that in her experience, most runners, when left to their own devices, do all of their easy runs at a faster-than-necessary pace. This not only negates the benefits of easy running; it hampers recovery so they aren’t able to push as hard during their fast runs, which ultimately diminishes the benefits of fast running too.
Basically, if you want to get the most benefit from your training, make sure your slow runs are truly slow and your fast runs are truly fast.
The bottom line
Fast and slow running each offer unique benefits, and one isn’t inherently superior to the other. That’s why Hamilton’s answer to the question “Is it better to run fast or slow?” is “Do both, please.”
Keep in mind that a running workout doesn’t need to be all slow or all fast. Hamilton is a fan of fartlek workouts where, after a sufficient warm-up, you toggle between short sprints and slow running. For example, you could run from one telephone pole to the next at a fast pace, and then take it slow until the next pre-determined landmark of your choice. Or alternate between a minute of hard effort and two or three minutes at easy effort. “You mix it up and you play [with your speed],” she says. “There’s something kind of invigorating about that.”
Related:
- The Workout That’s More Efficient Than Walking or Running
- How Frequently Should You Wash Your Workout Wear?
- Is Running Every Day Good or Bad for You?
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