HIIT vs LISS: Which is Better for Improving Your Fitness?

IIf you work out regularly, you probably already have a good idea whether you prefer short, energetic sweat sessions or more leisurely, long workouts. But when it comes to improving your cardio, it can be hard to know which one gives you more bang for your buck.

Two main categories of workouts are high-intensity interval training (HIIT) and low-intensity steady state (LISS). Both can improve your cardio fitness, but with different pros and cons.

That said, you don’t have to choose one or the other exclusively. In fact, incorporating both into your workout routine can help you reap the most cardio benefits.

“Incorporating one to two days of HIIT per week, with the rest of the workouts being LISS, creates a balanced approach that combines the benefits of both styles without the risk of injury and overtraining,” says Cassandra Padula Burke, CPT, RDN, personal trainer and owner of Catalyst Performance Lab.

Here’s everything you need to know about HIIT vs. LISS, plus sample workouts for both workouts.

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High intensity interval training (HIIT)

This type of cardio training pushes your body to its limit, or near limit!, for short periods of time, followed by a period of rest or active recovery.

Intense exercise, in particular, typically involves getting your heart rate to more than 70 percent of its maximum, according to the Cleveland Clinic. The basic formula for calculating your maximum heart rate is 220 minus your age.

“HIIT can be done through a variety of workouts, including running, cycling, bodyweight exercises, or even lifting weights,” says Emma Belluomo, CPT, a certified personal trainer and instructor for CycleBar.

These types of workouts are usually short, as the challenges usually last from 20 seconds to a few minutes. A HIIT workout can be as short as 10 minutes, plus warm-up and cool-down time, for a total of about 20 to 30 minutes.

Advantages

If you’re short on time, HIIT may be the most realistic way to fit in a good workout.

“HIIT is super efficient because it can provide the same benefits of a longer workout in a shorter amount of time,” says Belluomo. “Because you’re working significantly harder during those intervals of intense workout, you get a better cardiovascular outcome, which improves your endurance.”

People who did HIIT for four weeks actually had improvements in how well their bodies used oxygen during exercise, were able to exercise at a higher intensity before feeling out of breath, and also completed their workouts faster, according to a small 2017 study. International Journal of Sports Nutrition and Exercise Metabolism.

You’ll find that you reach your goals faster with HIIT. “It builds cardiovascular fitness faster than LISS because of the intensity of the workouts,” says Padula Burke.

And if you’re bored with your workouts, the variety of exercises during a HIIT workout might appeal to you. The alternation between work and rest can also make the workout go by even faster.

Disadvantages

HIIT workouts often involve high-impact exercises like jumping and running to increase intensity, but these exercises can also be stressful on your joints and put strain on your entire body.

“It’s important to balance HIIT with adequate recovery and make sure you don’t overtrain,” says Belluomo.

Some beginners may also find HIIT less accessible due to its intensity. (That said, keep in mind that you can still pace yourself during HIIT. Your max effort may not be the same as a friend’s max effort, which is fine.)

HIIT also puts you at risk for overtraining. People who started working out intensely almost every day developed rapid and severe declines in the function of their mitochondria (the energy producers in cells) and experienced signs of blood sugar problems, according to a small 2021 study in Cell metabolism.

Mitochondria are important for your overall metabolic health and muscle function. Reduced mitochondrial function is often seen in people who are insulin resistant.

Meanwhile, people who did HIIT routines three times a week for six weeks had less improvement in their blood pressure compared with people who exercised more moderately five times a week, according to another small 2021 study in Medicine and science in sports and exercise.

While HIIT can certainly be good for your fitness, it shouldn’t be the only tool in your workout repertoire.

Try this HIIT workout

For your own 20-minute HIIT workout at home, Belluomo recommends repeating the following circuit four times. To add more of a challenge, decrease the rest time to 15 seconds and increase the work time to 45 seconds.

“Incorporating one to two days of HIIT per week, with the rest of the workouts being LISS, creates a balanced approach that combines the benefits of both styles, without the risk of injury and overtraining.” —Cassandra Padula Burke, CPT, RDN

Low intensity steady state (LISS)

This type of cardio training involves doing an activity at a consistent, low to moderate pace for an extended period of time.

According to the National Academy of Sports Medicine (NASM), this typically means maintaining a heart rate of 45 to 65 percent of your maximum. For beginners, this may be lower and for more experienced endurance athletes, it may be higher.

“It keeps your heart rate in a lower but more stable range, which is still a great workout and also improves endurance,” says Belluomo.

You may associate LISS with “classic” cardio workouts, think: 30 to 60 minutes of walking or jogging on a treadmill. However, LISS can also take the form of biking, hiking, dance fitness classes or swimming.

Advantages

According to the NASM, steady-state cardio workouts like LISS can help improve both markers of aerobic capacity (when performed at moderate intensity) and muscular endurance.

Your heart responds to the increase in oxygen demand by increasing your cardiac output, making it easier for your body to deliver oxygen to all of its working muscle cells. In real life, this means you get less out of breath during daily activities, like playing with your kids or climbing stairs.

Over the course of 12 months, people who did only aerobic exercise showed more significant improvements in cardiorespiratory fitness than a group that did only resistance exercise, according to a 2024 study in the European Heart Journal.

“Because LISS is also more gentle, it’s something you can do every day without really stressing your body or worrying about burnout,” says Belluomo. “It’s also super accessible, because pretty much any type of cardio workout can be a LISS workout and you don’t have to plan specific reps or sets.”

Many LISS activities, like playing a game outside or riding a bike with a friend, also have a social aspect, which has its own benefits for your overall stress levels and health, according to the NASM.

Disadvantages

LISS is slow and steady, but that may also mean you reach your goals a little more slowly.

“While LISS is still a great way to improve your endurance, it will do so at a slower pace,” says Belluomo. “If you’re training for something that requires more endurance, it may not be enough of an effort for you.”

LISS workouts can also be boring because they involve doing the same workout for a longer period of time—at the same pace—rather than varying the movement and intensity like HIIT. If you’re short on time, LISS can also be harder to fit into your schedule.

Additionally, doing the same exercise over and over again can lead to a fitness plateau over the long term. As your fitness level improves, you should continue to increase your intensity to get into the right target heart rate range for your age, according to the American Heart Association (AHA).

“As your body adapts to the steady state of a LISS training routine, LISS workouts may become less effective at producing results, including improvements in fitness and endurance, without increasing the duration or intensity of the activity,” says Padula Burke.

Even if you choose LISS, you should still make sure to do a variety of exercises and activities to avoid plateauing. Also consider incorporating muscle-strengthening activities, such as resistance band or weight training.

Try these LISS workouts

With LISS, you don’t have to worry about reps or sets, so workouts are simple. Belluomo recommends one of the following to fit in a steady cardio workout:

• Take a brisk 30-minute walk
• Take a leisurely 30-minute bike ride on a relatively flat road
• Go for a light jog for 30 minutes

The heart of the matter

Both HIIT and LISS can help you improve your fitness, so which one you choose depends on your own preferences and goals.

While HIIT can be more effective for those short on time and who prefer variety in their workouts, LISS may be a better choice for those looking for a gentler workout or who find HIIT too hard on the joints. That said, both HIIT and LISS can have a place in your workout as you work toward your cardio goals.