LISS is a form of cardio that has actually been around for years but has recently come more into vogue as hardcore cardio fiends look for a break in their intensive training regimens. The acronym stands for Low-Intensity Sustained State.

In a nutshell, LISS is any form of cardio that you do at a slow and steady pace, typically half an hour to an hour. Basically, it's the antithesis of sprinting or interval training, like HIIT, which stands for High-Intensity Interval Training.

In high-intensity cardio, you are trying to raise your heart rate that is so intense it makes it hard to speak for a short period of time. For LISS, your activity is more moderate, so that you are able to speak well enough to carry on a conversation — like going on a jog with a buddy or working out on side-by-side stationary bikes at the gym.

Australian trainer and Instagram star Kayla Itsines is an advocate for LISS and uses the theory in the workout routines that have made her an internationally known fitness guru. Prior to her, bodybuilders in the 60s and 70s, as well as other fitness experts used LISS as a way to get lean when paired with super low-carb diets.

LISS is popular because it fits in with a variety of fitness goals. Because it is low impact and low risk, it is perfect for an active rest and recovery day. It can be a good way to build up to harder workouts for those that are just starting to exercise. It also presents a way to lose weight without exerting a lot of energy.

Activities that fall in keeping with LISS can be done with or without a gym, such as walking briskly or bike riding to work. It can also be swimming, setting your treadmill or elliptical at a steady pace or any other form of cardio that maintains a steady state.

Although LISS is a great gateway into fitness, it is best to use it along with other forms of cardio to avoid losing muscle strength with the fat loss you aim for. The best way to use LISS is as an active recovery if you are on a training schedule, or as a way to end a workout. And it pairs perfectly with HIIT for a weight loss tool.

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