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For many of us, cardio training is the bane of our existence. Regardless of whether you find it particularly exciting, the simple fact is we all like to stick to what drew us to train in the first place. Bodybuilders prefer a pump. Powerlifters prefer shattering their old PR. Fighters would rather hit mitts or spar.

Alas, if you’ve ever gassed out early during a training session, you know there’s no escaping the critical importance of cardio. As it’s been said, fatigue makes cowards of us all.

But what if there were a way to mix up your cardio routine that not only made this part of your regimen less monotonous but also economized your time and produced better results?

Enter high-intensity interval training, or HIIT. As compared to the more traditional concept of steady-state cardio training (jogging, for instance), HIIT takes less time, works your heart harder, and produces results steady-state cannot.

What are my cardio options?

For all intents and purposes, you have two options when it comes to cardio training: HIIT and steady-state. We would be hard-pressed to find a human being alive who isn’t familiar with the latter. Pick an activity that increases your heart rate and perform that activity for an extended period of time. Running, biking, stairs, swimming, and even walking are all popular choices.

On the other hand, high-intensity interval training seems to be less well-known—or, at least, less commonly practiced. With HIIT, the goal is to perform your activity as hard as you can for a brief interval (as little as 30 seconds works perfectly), followed by a rest interval not to exceed two or three minutes, ideally. Then repeat this cycle several times, targeting either sets or time to track your progress.

Each of these approaches has its respective benefits, and the difference in those benefits may help explain why neither should be dispensed with completely in any training program.

How do they differ?

Neither HIIT nor steady-state training has “cons” as far as results go. Rather, it’s the complementary way in which they round out your cardio training that makes them so distinct.

High-Intensity Interval Training

HIIT is anaerobic. This means the working intervals don’t depend quite so much on oxygen and are therefore fueled mostly by carbohydrates. As a consequence, HIIT will cause you to breathe harder and ultimately burn more fat. When you employ HIIT, your metabolism will remain elevated for hours—if not longer—after the completion of your workout. This one facet in particular makes HIIT a stand-out when it comes to fat burning.

HIIT also improves your “metabolic flexibility.” In other words, you will enhance your body’s ability to transition from fat-burning to carb-burning, which is important for overall health and athletic performance. This is especially crucial for athletes involved in sports composed of intervals between all-out performance and reduced effort, such as martial arts.

Last but certainly not least, the real beauty of HIIT comes from the economy of time. In fact, a 2012 study published in the Journal of Strength and Conditioning Research found six HIIT workouts performed over a two- to three-week period, each lasting only a few minutes, yielded observable improvements in critical areas of cardiovascular health.

You do the math.

Steady State

In contrast to HIIT, steady-state cardio is aerobic. This means your body requires oxygen to keep up and mostly burns fat. However, in the long term, steady-state doesn’t quite reach the same threshold as HIIT. In fact, as compared to HIIT, the results are somewhat staggering: A Queensland University of Technology study performed in 2009 had participants perform five weekly sessions of steady-state cardio for 12 weeks. On average, participants only lost seven pounds. Even worse, nearly half lost less than two pounds.

Steady-state cardio is not without its own unique benefits, though. Interestingly, this style of cardio may actually ignite growth in your heart’s left ventricle—the one that stores the oxygen-rich blood momentarily before pumping it out into your body. The relatively low intensity of steady-state cardio actually gives the ventricle time to completely refill between contractions, whereas this might not occur with HIIT. As a result, steady-state cardio may drop your heart rate both at rest and during exercise. This not only indicates good heart health but also points toward an increased ability to relax, focus, and recover from stress.

What’s the bottom line?

None of this is to say a dedicated jogger should give up everything he or she knows in favor of HIIT. Rather, both systems are made to be complementary. An MMA fighter can’t reasonably expect to go the distance in a five-round bout without some form of endurance training in camp. In the same light, that fighter also shouldn’t expect to have the metabolic flexibility to throw more than one or two series of deadly combinations in a single round and not gas out.

As with all things in life, an optimal starting point is to ascertain your training goals. If it’s fat loss, perhaps HIIT should take precedence. If it’s cardiovascular health and relaxation, it’s probably okay to focus more on steady-state.

For well-rounded training and athletic performance, though, give each its due.

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