Something people seem to have a real Goldilocks complex with.
They either hate it or they love it; they do way too much of it, or do none at all. It seems to be hard finding a happy medium with cardio.
If you're someone looking for that middle-ground, then you're in the right place. With cardio being such a hot-topic in fitness discussions all the time, I figured it was time to address some of the thoughts out there on it and the two forms most used for it.
Lets start by first taking a look into LISS...
Low Intensity Steady State (or LISS) cardio consists of doing low-moderate intensity work (50-60% of your maximum heart rate) at a consistent pace, typically for a long duration. For example, using the stair-stepper or biking at a steady pace/steady level.
While this type of cardio may sound boring to some, it is actually pretty important and shouldn't be overlooked! To start, LISS is a great form of cardio for anyone either new to fitness or with joint pains/problems. This is because it doesn't place a lot of strain on your body, which also makes it safe to be done multiple times a week.
LISS has also been said to increase blood flow to your muscles. This means it can reduce the risk of delayed onset muscle soreness. Think of it as an active recovery as steady-state cardio can be a great way to end a tough training session, whereas a more intense form could hinder your recovery by training intensely over sore muscles.
Now, an area of LISS that is still quite grey is "fat burning". You may hear often that LISS is prime for preserving muscle while burning fat because you enter a "fat burning zone" due to your target heart rate during it. The thought is that keeping a low heart rate for a long, steady amount of time allows your body to primarily burn body fat as opposed to glucose (which can be burned during higher intensity, anaerobic cardio). However, there have since been more and more studies coming out suggesting that HIIT can be more muscle sparing due to it requiring more muscle activation.
So, what is HIIT?
High Intensity Interval Training consists of short, all-out intervals coupled with low-moderate intensity work. For example, a 30 second sprint followed by a 3 minute steady-pace walk to cool-down, then repeating the sprint/rest cycle a few more times.
Now, this type of cardio is much shorter than LISS as the intensity level makes it less sustainable for long durations of time. As well, its intensity level doesn't make it a strong cardio-option to do multiple days in a row. Doing HIIT 5-6 days a week will actually have a negative impact on your weight training and muscle growth eventually.
It's not all bad, though! In conjunction with the time saving and less "boring" workout, another great aspect of HIIT is its ability to create metabolic change. Whereas our bodies/metabolisms may start to adapt to long durations of LISS cardio (thus we stop seeing positive responses/results from it), HIIT cardio has the ability to hit both your anaerobic threshold (AT) and lactate threshold (LT)-- 2 important predictors of performance in cardio. This then produces ATP (quick burst of energy given to the muscles when they are contracted) and causes your body to experience metabolic changes.
These changes in the metabolism are actually changes in your mitochondria density of your muscles and they allow you to burn calories/fat both during and after your cardio-session. In other words, studies have shown that with HIIT, you can achieve a longer caloric burn. However, because LISS stays below LT and AT, you only burn calories at the precise moment of your cardio-- there is no 24 hour energy expenditure (or boost in metabolism).
All that being said, HIIT or LISS? Which one should we do??
While both definitely have their positives...
- LISS is easier on the joints
- LISS is much more mind-less and allows you to multi-task during! (I like to read during my LISS sessions...)
- LISS can be done multiple times a week
- LISS is great post-tough workout and for recovery
- LISS burns fat
- HIIT is constantly changing throughout the workout, so it is less boring
- HIIT is more time-efficient
- HIIT allows your body to burn calories well after your session is over
- HIIT provides more of a challenge
- HIIT can naturally increase your metabolism
- HIIT burns fat
They also have their negatives...
- LISS is not time-efficient
- LISS can be mundane and "boring"
- Our bodies and metabolisms can adapt to LISS
- You only burn calories in the moment with LISS
- HIIT cannot be done multiple days a week/in a row
- HIIT is very challenging and could be dangerous if not used right
- HIIT requires more concentration than LISS
Personally, I don't think you should pick any one over the other!
When looking at the pros and cons of both, it is easy to see that there is actually room for BOTH in your weekly workouts! Combining both HIIT and LISS is the best formula (in my opinion) and may be just the solution you need to finding balance with your cardio integration!
At the end of the day, it is all about making your workout work for you-- try out both styles, see what you like, and finally find a fix to that too-litle-too-much-not-enough Goldilocks problem!