So You Want to Improve Your Cardio? Experts Share Whether to Focus on HIIT or LISS Workouts

If you regularly work out, you probably already have a good sense of if you prefer short, high-energy sweat sessions or more gentle, long workouts. However, when it comes to improving your cardio, it can be difficult to tell which gives you a better 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 exclusively opt for one over the other. In fact, including both in your workout schedule may help you reap the most cardio benefits.

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

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

High-intensity interval training (HIIT)

This type of cardio training pushes your body to its max effort—or close to it!—for short periods of time, followed by a period of rest or active recovery.

In particular, high-intensity exercise usually means getting your heart rate to more than 70 percent of its maximum, per 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 different workouts, including running, cycling, bodyweight exercises, or even while lifting weights,” says Emma Belluomo, CPT, a certified personal trainer and instructor for CycleBar.

These types of workouts are typically short, since the bursts of challenges are usually just 20 seconds to a few minutes. A HIIT workout can last as little as 10 minutes, plus warmup and cooldown time—so, about 20 to 30 minutes total.

Pros

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

“HIIT is super efficient because it can provide the same benefit of a longer workout in a shorter amount of time,” Belluomo says. “Since you’re working significantly harder during those intervals of intense work, you’ll get a better cardiovascular result, improving your endurance.”

In fact, people who did HIIT for four weeks had improvements in how well their bodies used oxygen during exercise, were able to exercise at a higher intensity before losing their breath, and also completed their workouts more quickly, per a small 2017 study International Journal of Sport Nutrition and Exercise Metabolism.

You may also find you reach your goals more quickly with HIIT. “It builds cardiovascular fitness faster than LISS due to the intensity of the workouts,” Padula Burke says.

Plus, if you tend to get bored with your workouts, the variety of exercises throughout a HIIT workout may appeal to you. The alternation between work and rest can also help the workout go by even faster.

Cons

HIIT workouts often incorporate high-impact exercises like jumping and running to rev up the intensity, but these can also stress your joints and be taxing on your body overall.

“It’s important to balance HIIT with adequate recovery and ensure you’re not overtraining,” Belluomo says.

Some beginners may also find HIIT less accessible because of its intensity. (That said, keep in mind that you can still go at your own pace during HIIT. Your maximum effort may not be the same as a friend’s maximum effort, which is perfectly okay.)

With HIIT, you also run the risk of overtraining. People who began working out strenuously almost every day developed quick and severe declines in the function of their mitochondria (the energy producers inside cells) and experienced signs of blood sugar issues, per a small 2021 study in Cell Metabolism.

Mitochondria are important for your overall metabolic health and muscle function—and reduced mitochondria function is often observed in those who are insulin-resistant.

Meanwhile, people who did HIIT routines three times per week for six weeks had less improvement in their blood pressure compared to people who worked out more moderately five times per week, according to another small 2021 study in Medicine & Science in Sports & Exercise.

While HIIT can certainly benefit your cardio, 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 a greater 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 remainder of workouts being LISS, provides a balanced approach that incorporates 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 means doing an activity at a consistent, low to moderate pace for a longer period of time.

It typically involves maintaining a heart rate of around 45 to 65 percent of your maximum, though this may be lower in beginners and higher in more experienced endurance athletes, per the National Academy of Sports Medicine (NASM).

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

You may associate LISS with the “classic” cardio workout—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.

Pros

Steady cardio workouts like LISS can help improve both markers of aerobic capacity (when done at moderate intensities) and muscle endurance, per the NASM.

Your heart reacts to the increases in oxygen demands by boosting your cardiac output, so your body can more easily deliver oxygen to all of its working muscle cells. In real life, this translates to getting less winded during everyday activities, like playing with your kids or going up and down stairs.

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

“Since LISS is also more gentle, it’s something you can do every day with no real negative strain on your body or fear of burnout,” Belluomo says. “It’s also super accessible, as pretty much any form of cardio exercise can be a LISS workout and you don’t need to plan out specific reps or sets.”

Many LISS activities like playing a game outside or biking with a friend also incorporate a social component, which has its own benefits for your overall stress levels and health, per the NASM.

Cons

LISS is slow and steady, but that may mean you reach your goals somewhat more slowly, too.

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

You may also find yourself getting bored during LISS workouts, since they involve a longer stretch of the same workout—and the same pace—rather than switching up movement and intensity like HIIT. If you’re short on time, LISS can also be harder to fit into your schedule.

Plus, doing the same exercise repeatedly in the long-term can lead to a fitness plateau. As your fitness level improves, you’ll need to continue increasing your intensity to get in the appropriate target heart-rate range for your age, per the American Heart Association (AHA).

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

Even if you opt for LISS, you should still be mindful of doing a variety of different exercises and activities to avoid a plateau. Consider also including muscle-strengthening activities like working out with resistance bands or weights.

Try these LISS workouts

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

• Complete a brisk, 30-minute walk
• Take a gentle, 30-minute bike ride on a relatively flat road
• Go for a light 30-minute jog

The bottom line

Both HIIT and LISS can help you improve your cardio, so the one you choose may simply come down to your own preferences and goals.

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