LISS VS. HIIT: Which is the superior form of cardio?

​Walk into any gym and you will see examples of LISS (low intensity steady state) and HIIT (high intensity interval training) cardio. Who has it right though? Is slow and steady over a longer period of time better? Or does fast and furious produce a bigger bang for the buck? No one wants to waste time, and certainly not energy.

​LISS and HIIT are both excellent forms of cardio. One is not superior. Both burn fat and improve cardiovascular fitness. However, there are several things to take into consideration before deciding which will work best for you. 
 
In recent years, there has been a lot of buzz surrounding HIIT. Most people instantly think doing more strenuous workouts in less time is the best way to go. After all, time is a precious commodity. With busy work schedules, shuttling kids, and other daily activities, who has time to walk on the treadmill for an hour? But can you burn enough calories in a very short amount of time to reduce fat? Let’s dive in.

HIIT
HIIT does not have a universal definition. Put simply, it is a series of INTENSE bouts (sprints) of exercise interspersed by periods of rest. There is a lot of variability between protocols. Two people performing HIIT sessions, may appear very different. The important takeaway is exercising near or at maximal effort for short periods. Then taking a break and doing it again. 
 
Sprints, or “all-outs” feel grueling when done correctly. They are typically less than 45 seconds. The work output can range anywhere from 1:1 to 1:10. What does this mean? If you are working in a 1:1 ratio, your sprint might be 30 seconds, so your recovery would be 30 seconds. This might not sound difficult, but anyone who has done 10, 30 second sprints, with 30 seconds of recovery knows how exhausting this work feels.

​One popularized form of HIIT is Tabata. Tabata training works in 20 second intervals, followed by 10 seconds of rest, and repeated 8 times, for a total of 4 minutes. How great would it be to have your workout completed in 4 minutes? A textbook Tabata session is extremely difficult though and not for the faint of heart. I have been training clients for over 15 years, and there are only a few that could truly benefit from this protocol. 
 
Beginners might need to follow a more intuitive approach for HIIT. You can do a 20 second sprint and when you feel like your heartrate has recovered, go again. This might mean resting for 2-4 minutes. Resting too long will not elicit the same response though. When you rest, don’t come to a complete stop. Keep moving, just slower. 
 
Intermediate and advanced levels, can use a timed approach. I myself, like a 1:2 ratio. This means, go all-out for 30 seconds, and recover for 60 seconds. If my heartrate is still quite elevated, then I add another 30 seconds to my recovery time. Nothing is ever set in stone. Total HIIT time should be less than 30 minutes. If you warm up for 5 minutes, complete 10-12, 30 second all-outs, and recover for 60 seconds, you’ll be done in less than 25 minutes. I like to add a 5 minute cool-down, which gets you to the 30 minute mark.
 
HIIT variety
While many people use traditional cardio machines (treadmill, rower, or stepper) for HIIT, there are endless ways to incorporate this style of training into your program. One exercise or several exercises can be combined in a circuit. For people who are easily bored, have limited equipment, or just hate the idea of getting on a machine, this is for you. 
 
Here is an example of how you can turn one exercise into a HIIT workout:
Warm-up for 5 minutes with a fast walk or jog.
Ball slam* for 20 seconds.
Recover for 60 seconds.
Repeat 8-10x.
*Insert any exercise here that you can really push hard, such as High Knees, Mountain Climbers, Jump Squats, Battle Ropes, etc.

​Is HIIT for everyone? Definitely not. Some people don’t like to work at such a high capacity and it is totally fine. Also, if you have high amounts of stress, either from work, family, or already train with a high intensity level, you might benefit more from LISS.
 
LISS
LISS involves slow aerobic activity such as walking, jogging, swimming or cycling. It is also much easier than HIIT and usually the best place to start exercising for sedentary people. Low intensity feels much more enjoyable for most people. It also helps that you can do many LISS activities outside of a gym. A long walk on a sunny day has tremendous physical, as well as psychological benefits. 

It is recommended that adults complete at least 150 minutes of physical activity each week. Does this mean you can do all 150 minutes in one day? Sure, but I don’t advise this. LISS is most beneficial with frequency. When you consistently exercise for 30 minutes, 5 times each week, you are settling into good, healthy habits. I encourage all of my clients to walk for 30 minutes each day. This can be broken up into 3, 10 minute walks. Most people have more time on the weekends, which is perfect for longer walks or bike rides. 
 
Also, with LISS, you can do other things while you’re in it. You can carry on a conversation, listen to a podcast, although it is not ideal, you could read. There is no way you can manage any of these, while performing HIIT. 
 
CONCLUSION
One of the main barriers to exercise is a perceived lack of time. HIIT training represents a more time efficient way to accomplish exercise goals. If you thrive on working up a sweat and pushing very hard, then HIIT is for you.  If you hate high intensity cardio or have injuries to work around LISS is an excellent option. Which form of cardio are you consistent with? That is the one you should do.

If you don’t have any specific goals, you can incorporate HIIT and LISS into your program to optimize your cardiovascular fitness. It is all about assessing your current recovery level, lifestyle, schedule, and goals. Then determining the best route to take, based on what YOU can adhere to and remain consistent.