How to Safely and Effectively Progress Your Interval Training

This type of structured training builds speed and offers new challenges for both beginner and experienced runners. Here’s how to do it right.

black woman running on track
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Consider speed a goal that never goes out of style. Whether you have a (likely virtual) race on the calendar, or you’re just bored with your run routine and need a new challenge, intervals should have a place on your run schedule to build that speed.

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Picking up your pace through interval training has countless advantages for your overall performance, on and off the track. This type of work helps you gain a more efficient stride and improve your VO2 max, says Nell Rojas, USATF-certified run coach and certified personal trainer in Boulder, CO, and Honey Stinger-sponsored athlete. Science backs this up, saying intervals can improve power, reduce time to exhaustion, better your VO2max and boost heart health.

On the mental side, interval training puts you in a mindset of pushing through the burn and getting comfortable with being uncomfortable. “One of the biggest benefits to incorporating intervals is that you get to change things up a little bit,” says Steve Stonehouse, USATF-certified run coach, certified personal trainer, and director of education for the running studio, Stride. “From a mental stimulation standpoint, you have to challenge your mind to focus on a specific pace,” rather than zoning out and just checking off miles as you might do on long-distance, relaxed-paced runs.

Plus, intervals build the aerobic capacity needed to do those longer runs, which is important for all runners but especially those new to the sport. Someone who hasn’t run much, for example, might find the idea of running 30 to 40 minutes non-stop an intimidating feat. But five or 10 minutes with walk breaks? That’s doable. “Confidence building is a big benefit,” says Stonehouse.

To top it off, because you’re accelerating and decelerating, you strengthen your mechanics and become a more well-rounded runner. “Running intervals allows for an increase in intensity and creates a contrast between the work interval and recovery period—this contrast can really awaken muscles that often get a little ‘sleepy’ from constant steady pace mileage,” says David Siik, fitness coach and creator of Precision Run treadmill training at Equinox and Variis instructor.

So how do you make sure you’re using interval training to your advantage? And how do you keep up the challenge? We asked coaches to share their best tips for starting and then progressing intervals effectively. Here’s how.

Start slow and test your pace.

If you’re new to running or you’re doing interval training for the first time, start slow even on the work periods, and get to know your speed. For someone who hasn’t run much before, Stonehouse suggests doing a 10-minute jog followed by a 2-minute recovery walk and repeating that for a total of 3 rounds.

Rojas also suggests a Fartlek run to get used to the idea of intervals and to learn how bursts of harder work feel. For these types of runs, you’ll base your performance on rate of perceived exertion (or RPE), with one being super easy and 10 being your all-out effort. For a Fartlek, aim for an effort of about 7 out of 10 as you run for 2 minutes or from one tree, lamp post, or mailbox to the next and then rest for 30 seconds or until you feel ready to repeat that work interval. “This prepares the legs and gets them used to turning over faster,” Rojas says. “And because these are off-track and based more on time, you can really listen to your body instead of going for a certain pace.”

Use your pace to set your goals.

While no-pace Fartleks are a strong start, you’ll eventually want to set a pace goal for your intervals. As a general rule for new runners, Siik suggests going off RPE for high-intensity intervals under 4 minutes, but focusing on a set pace for efforts longer than that.

If you’re an experienced runner, pace goals for intervals are especially helpful when you’re trying to increase your overall speed. For people who want to get faster at longer distances, like half marathon to marathon, Rojas and Stonehouse both suggest 1-mile repeats for your interval training days, with 1 to 4 minutes of rest between those mile pushes.

To help you determine a goal pace for those mile repeats, it’s helpful to know all your paces, from mile pace to 5K, to half marathon and marathon. If you have a recent (in the past month or two) mile, 5K, 10K, half marathon, or marathon time, you can pull your average mile pace and then use our pace calculator to determine your other goal times.

“When I’m coaching someone at a half-marathon distance or marathon or greater, one of the most important things to understand is pacing,” Stonehouse says. “That’s the only way programming works.” You need to know what a certain pace feels like and what it feels like to maintain it, he adds. That’s the benefit of longer intervals.

To set a goal mile pace for each interval, Rojas also uses Jack Daniels’ VDOT chart. But it might take some trial and error to figure out the goal that’s best for you, Stonehouse says. Once you get to know how fast you run and how long you can maintain a certain speed, then you can better program your intervals.

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Consider work-to-rest ratios based on intensity.

For interval newbies, Siik always suggests a 1:2 ratio of work-to-rest to keep it safe. For example: after a warmup, run hard for 30 seconds, following by 1 minute of rest or walking recovery. But if you often practice interval training, consider how intense you’re working to set the ratio.

For example, if you’re doing mile repeats, you’re likely running hard for at least 5 minutes, more likely 7 or 8 minutes. And because those intervals are long, you should be working at 85 percent of your max effort (compared to 90 percent as you’d do for shorter, quicker intervals). For that, you want to rest for 1 to 3 minutes, making your work-to-rest ratio more like 5:1.

On the other hand, if you’re doing 400-meter repeats (about a quarter-mile) in 75 seconds, you’ll want a higher rest ratio, maybe pausing for 2 to 4 minutes, Stonehouse says, making that ratio around 1:3. The bottom line: The more intense the work, the more rest time you’ll need.

Think about your goals for your progression.

Run coaches have different approaches for how to progress your intervals (that is, whether you should first cut back on rest time or add to interval time). But ultimately, it comes down to what you’re striving to achieve.

If you’re going after a longer distance PR, like a half marathon, cut down on rest time before you speed up or add distance. “With long-distance runners, I always decrease rest time before increasing speed. That’s going to continue building aerobic capacity and make them stronger,” Stonehouse says. Once you’ve cut your rest time way down, then increase the length of the work interval (take 1-mile repeats to 1.5-mile repeats, for instance), still focusing on the set pace.

For shorter-distance goal times—or even if you’re just playing around with intervals and have less of a time goal in mind—consider lengthening the intervals, before you cut back on rest time, Rojas suggests. If you start with 30-second pushes, for example, go up to 45- then 60-second efforts, while maintaining a 1-minute break between those pushes until you end up at a 1:1 ratio. Or do 200-meter pushes, then bring it up to 400, then 600, maintaining the same rest breaks as you build distance.

Either way, make sure you rest.

No matter what type of interval training you’re doing, you need that rest break. Whether you jog or walk during that recovery time (or even stop completely) is a personal preference and depends on what you can handle and what will bring your heart rate down fastest. Rojas says she normally suggests jogging, but some people need to walk or a full stop and that’s OK too. Siik often recommends starting with a recovery jog after the first interval or so, then bringing it down to a walk in the later intervals, if necessary.

Don’t lay it all out on the first interval.

Your final interval should be faster than your first, says Rojas. Pace yourself on those big pushes so you have room for improvement—and enough energy left to speed up for your final push. That’s how you finish strong.

Know when it’s time to bump up to the next level.

To figure out when to progress your intervals, pay attention to your exertion levels. If you have 3 minutes to rest between intervals, and you’re itching to go again after 60 seconds, then it’s probably time to switch it up, Stonehouse says.

Or if you’re cruising through 400-meter dashes with ease, start aiming for 800s. If you realize you’re totally wiped after the first couple intervals and have more to go, don’t be afraid to drop it back, giving yourself more rest or shorter work bursts. Easy breathing and less soreness post-interval run can also be signs you’re ready to turn it up, Siik says.

Limit the frequency.

Because you’ll be training at a high intensity with intervals, you don’t want to do it every day. Rojas and Stonehouse recommend sticking to one or two days a week with easy or rest days in-between. That could mean you do mile or 800-meter repeats on Tuesday and a tempo run (a comfortably hard run, where you push the pace to something you can maintain for a few miles, another form of interval training) on Thursday. This should help you avoid injury.

Finish knowing you could do more.

One thing most runners have trouble with: not going all out, all the time. If you’re doing mile repeats at a set pace, even if you have some gas in the tank on that last mile, you still want to stick with your pace, rather than speed it up. “If you have some left, do another rep, not a faster lap,” says Stonehouse. “The most common mistake I see when people start doing intervals…they just haul ass on the track for no reason. They lose sight of the pace they should train at and just focus on going fast.”

But you want to be disciplined, he says. If you feel really good at the end of an interval day, consider picking it up the next time, but you shouldn’t be crawling off the track, either. “It’s OK to finish a workout and feel strong and not beat up,” Stonehouse says.

Plus, training isn’t race day. Yes, you’re prepping for faster finishes one day, but you don’t need to leave it all out there right now. Maintaining control will help with injury prevention and actually make you want to come back for more. “A 90 percent effort is a great place to be; 110 percent might be right there but avoid going for it,” Rojas says.

Take time to warm up and cool down.

To have a successful interval session, whether it’s your first one or fiftieth, you need to do a dynamic warmup to prep your body, Stonehouse says. “You’re going harder, so the risk of injury increases,” he says. Unlike long runs, when you have a mile to settle in and get your body moving, intervals start out faster, so you need that prep time.

Stay focused.

Intervals offer a powerful mental tool, because you’re basically forced to pay more attention to your effort so you can get the most out of your run. But you do have to stay in the moment to make that happen.

“You’ll be amazed how much you can increase the quality of your workout (and how much you improve) when you focus a little less on your favorite song, competing with others, or being entertained,” Siik says. “Those things can be motivating, but the moment you move them to the backseat and let the quality of your programming become the focus, you suddenly feel connected to the run in a deeper and more meaningful way.”

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