Treadmill sprint workouts will help you hit your next PR while giving you the benefits of a HIIT workout.
Woman doing a treadmill sprint workout
Credit: skynesher/Getty

If you're a runner, there's a strong chance you consider yourself a member of one of two camps: You're either a cheetah-like sprinter who can easily race a 400-meter dash in a few beats but can't jog longer than a 5k, or you've got a "slow and steady wins the race" mindset and can run a full marathon without your legs giving out.

And while you might be perfectly content sticking to your favorite, you could be missing out on some health and workout perks by doing so. In fact, varying your running workouts (with things like treadmill sprint workouts) will help you avoid injury, score PRs, and make you a better and stronger athlete all-around. (See: Is It Better to Run Faster or Longer?)

"Sprints are beneficial even for very long-distance runners because of how they affect the neuromuscular connections between your brain and your working muscles," says Laura Norris, an RRCA-certified running coach in Northwestern Indiana. "When you do sprints, you're teaching your body to run very fast, and that trains your brain to communicate more quickly with your muscles. So when you're running at an easy pace, which most runners do for a majority of their runs, you're more efficient." 

Gaining quick feet and better running form aren't the only benefits of sprint workouts, either. "It's kind of like a high-intensity interval training (HIIT) workout, with these hard bouts and really relaxed bouts, so your cardiovascular system is going to benefit a lot from your heart rate going way up for those sprints and recovering really slow," adds Amanda Nurse, an RRCA-certified running coach in Boston. "That's going to help with both your endurance and speed." (And, in case you didn't know, HIIT offers some pretty incredible benefits.)

Pounding the belt is one of the easiest ways to get the job done. Removed from the ever-changing elements and tucked away in their own blissful bubble of sweat, treadmills allow you to train at any time, helping you maintain consistency in your training schedule that ultimately leads to improvement, says Norris. Plus, you're able to set your exact pace—and hold yourself to it throughout the entire sprint, adds Nurse. 

But if the word "sprint" sends chills up your spine, don't sweat it. Here, Norris and Nurse explain how to build your own treadmill sprint workout that you won't completely dread.

How to Build a Treadmill Sprint Workout

Before you hop on the treadmill and crank the speed up to 10, there are a few things you need to keep in mind. For starters, a treadmill sprint workout—and sprints in general—aren't the best idea if you're a total newbie. Norris recommends running for at least six months before trying a sprint workout, which will be enough time to get your body used to the impact of running and ensure you won't get injured.

If you're dying to give sprints a shot early in your running career, try a more gentle running interval workout: Start in a really light jog. After you've warmed up a bit, pick up your speed (about 30 seconds per mile faster) for 10 to 20 seconds, then slow down to a walking speed, says Nurse. Try one of these "sprints" after you've thoroughly warmed up (think: you've lightly jogged for seven to 10 minutes), and then see how your body responds. If it feels like a manageable challenge, repeat four to five times. This type of workout will help you work your way into sprints without pushing you to hit your all-out max effort, which can be overwhelming (not to mention increases the injury risk) for a new runner, she explains. (Related: How to Start Running for Beginners

Setting Your Speed

Even if you consider yourself an intermediate runner and have done your fair share of outdoor sprints, your sprint speed on the treadmill might not be as fast. "Runners tend to take longer strides on the treadmill, and they'll take shorter, faster strides outside," says Norris. "I also think some people have the tendency to sit back on the treadmill, while most people lean slightly forward outside." While seemingly tiny differences, they can actually make you a slower runner indoors, she explains. 

So how fast *should* you sprint during a treadmill sprint workout? First, you need to determine your "easy pace," or the speed at which you can run or jog and still comfortably have a conversation with someone (a little something called the talk test), says Nurse. Your effort here–aka your rate of perceived exertion (RPE)–might feel like a 3 or 4 out of 10, adds Norris. For your sprint, you'll often want to aim to hit a speed that feels really fast but doesn't require *all* of your energy, which would feel like a 9 out of 10 on the effort scale, says Norris.

In any case, you should always start your sprints at a speed that's slightly slower than what you think you can run. "I think people have a tendency to overestimate on the treadmill," says Norris. "If you think your sprint speed would be 9 mph on the treadmill, I'd recommend setting it at 8.5 mph to 8.7 mph at first because it's better to do it with good form than to do it too fast." And that's also super important in making sure you're sprinting safely: You need to be confident your legs can handle the speed, says Nurse.

After you do a few sprints at a slower speed, check in with yourself: If it feels like a challenge, that's a good speed for you to be at, and if it doesn't, you can slowly bump it up by 0.5 mph at each interval, adds Nurse. 

The Length and Number of Your Sprints

In general, you'll want to sprint for 20 to 30 seconds, which is long enough to get the benefits but not ~too~ long that you'll start using your anaerobic energy system, which creates lactic acid that eventually makes you feel fatigued, says Norris. And if you're trying to hit your absolute maximum speed, the longest you're going to be able to stick to it is for about 45 seconds, which is when you'll hit the lactate threshold, says Nurse. As you exercise and your body uses up carbs for energy, it creates lactate as a byproduct, and when it accumulates in the blood faster than it can be removed (re: you reach the threshold), you begin to experience muscle fatigue. Translation: Your sprint's going to start looking a lot more like a jog.

In between your sprints, you'll need to rest and build up some energy for the next one. The general recommendation is about a 4:1 rest-to-work ratio. So if you're sprinting for 30 seconds, you might rest for 2 minutes in between. The more experienced you are, the shorter you can cut your rest intervals. "The rest intervals are so long because you want your muscles to recover fully between sets," says Norris. "Sprinting recruits type-IIx muscle fibers which have a high power output but also tire quickly."

The number of sprints you do in a typical treadmill sprint workout depends on your experience level, too. A beginner runner should aim to do four to five sprints with recovery jogs in between, while an advanced one might strive for 10, explains Norris. (Related: Everything to Know About Slow- and Fast-Twitch Muscle Fibers)

Adding Incline

FYI, you'll always want to do your treadmill sprint workout at a 1 percent incline, as treadmills naturally have a decline at their base. That said, you can add an even greater steepness to up the ante—and you don't have to be an advanced runner to do so. "You can skip flat sprints and go straight to the incline because there's less impact when you run uphill," says Norris. "For beginners, injury-prone people, or people who might not do a lot of sprints, those uphill ones can actually be best because you're less likely to get injured doing them." One primary reason: On an uphill grade, runners adopt a mid-foot or forefoot strike pattern, which reduces the severity of the foot's impact and the frequency of it along a specific part of the tibia, according to a 2016 study published in Sports Medicine. (Psst. Here's everything you should know about running form.)

For each sprint, Norris recommends setting your incline to 5 or 6 percent, which will noticeably feel like you're going uphill, while Nurse suggests keeping it at 2 to 5 percent, mimicking natural hills you'd come across during an outdoor race. Just like you would do for your speed, try starting your sprints on a lower incline and slowly increase it to meet your comfort level and running style. (Again, safety should be your number one priority!)

After your burst, bring your incline back down to a flat road. Whichever incline you choose, know that your speed is definitely going to be lower than it would if you were running on a flat treadmill–but you're still getting a crazy good workout. "It's an awesome way to gain fitness," says Nurse. "Hill running even further enhances your proper running form and efficiency." But no matter how you style your sprints, tackling a treadmill sprint workout once a week—in addition to two to five other runs—can improve your speed in as little as three to four weeks, says Norris. 

25-Minute Treadmill Sprint Workout

Ready to try a treadmill sprint workout but not sure how to start? Follow Norris' plan below, using your rate of perceived exertion (RPE) to guide your speed. Note that the sprint begins once the belt reaches the desired incline.

Graphic of 25-minute treadmill sprint workout
Credit: Yeji Kim