Due to recent government-mandated lockdowns, many people have understandably found themselves quite limited in terms of training resources. Those used to regularly utilizing the likes of heavy weights, complex machines, and vast amounts of space have been relegated to using whatever is available in their own homes to train with. Although it’s looking like things will soon be going back to normal for residents of many states (some much sooner than others), I wanted to go ahead and write this post to clarify a few things about a style of training many (including myself) have employed during this time: HIIT.
Disclaimer: The commentary in this post is written mainly concerning those with a current or future goal of losing body fat, or at least maintaining current body composition and negating body fat gain.
For those unfamiliar with it, HIIT stands for High-Intensity Interval Training. Although you can find a lot of people out there peddling HIIT as if it’s a specific program that they’ve taken to perfecting with their obviously superior training intellect, in reality it’s just an umbrella term. Examples include any kind of Tabatas, Circuits, Metcon, Complexes, EMOMs, Accumulations, etc. In short, any kind of training that involves high-effort exercise done for short bouts of time broken up by short rest periods. Opposite means of training would, by definition, be low-intensity, steady-state (also referred to as LISS) exercise done for longer periods of time; stuff like walking, jogging, most “cardio” machines, etc.
So now that we have some clear definitions and examples in mind, it begs the question:
Why did so many people switch to HIIT?
Although I will shortly make a separate argument for the case of HIIT training (with some cons sprinkled in thereafter), I think there are a few main (less scientific) reasons for its recent appeal:
- HIIT training (if done right) is challenging. If you’re someone who finds virtue in overcoming both the physical and psychological barriers of difficult workouts, it’s easy to create your own difficulty with HIIT, where the name of the game is high effort/short rest.
- HIIT training allows for endless variation. If you have training A.D.D., toying around with innumerable selections and orders of exercises probably sounds a lot more fun than doing the same thing on a treadmill for an hour.
- HIIT training makes you feel like you’ve really done something. Even in relatively short workouts, intensity and rest times can be scaled appropriately to make sure that in almost no time, you feel out of breath and sweaty with wobbly legs and the heartbeat of a hummingbird.
To go along with these reasons, as mentioned before, many people don’t have a ton of equipment to choose from at home. However, as long as they’re meeting the above criteria in their minds, they don’t need much equipment to get the job done. This combination makes HIIT an ideal alternative for a lot of folks, including those who were training a bit differently before this whole ordeal.
However, there is also one more pseudo-scientific claim that a lot of people also cling to regarding HIIT, that being that “HIIT is superior for burning fat compared to other training methods/protocols.”
Well, it depends.
I used the term “pseudo-scientific” above because, as is the case with most of these topics, there is always some grain of science or proven evidence that people cling to when making these kind of bold claims. But, also as is the case with most of these topics, there is one thing that absolutely can’t be overlooked at the beginning of analyzing the case and forming a claim… and that thing is CONTEXT.
The heart of the fat-burning matter
Calories.
Really, that’s it. I could leave things at that, but perhaps I should elaborate a little.
When discussing the topic of fat loss, it’s crucial to keep the things that affect it in rank-order. For instance, a lot of people will argue the opposite of the previously mentioned claim; that LISS is superior for fat loss because more of the fuel being burned for it comes from fat stores. While the fuel mix statement is factually true in a standalone sense, the argument as a whole can quickly lose its validity based on other factors. The most paramount factor in this case is being in a caloric deficit, or burning more calories than you consume. In other words, you could follow a LISS training protocol and tell yourself that your body is a fat-burning machine, but this assertion is entirely false if you are regularly consuming a surplus of calories. Rank-order.
Allow me to build a hypothetical scenario to illustrate this further:
Ned follows a LISS protocol in which he burns 300 calories in a little over an hour jogging on the treadmill. Combined with his nutritional habits, this allows him to average a 200-calorie deficit each day.
Fred follows a HIIT protocol in which he also burns 300 calories in a 35-minute workout. Combined with his nutritional habits, this allows him to also average a 200-calorie deficit each day.
Given that Ned and Fred are physiologically identical in this situation, who is burning more fat?
The answer is neither, since they are both consistently putting themselves at the same level of caloric deficit.
This is a somewhat comforting realization to make, because most people are relieved to find that fat loss is not so much about the specifics of your program or diet, but rather about how you are meeting the end goal of consistently expending more energy than you consume. That sentence alone sums up probably 95% of my view on the matter.
In other words, an argument for fat-burning superiority can be made for both LISS and HIIT, depending on the big picture outcome of what allows you to consistently burn more calories.
Now that I’ve hammered that overarching factor in the ground though, let’s go back and examine another important variable from that scenario: time.
The Calorie-Time Continuum
Though time is usually not viewed as a tangible variable, it is nonetheless quite a valuable resource for most of us. Without harping on this fact for too long, let’s just all agree: we are all busy with our own respective priorities and responsibilities, therefore time is of the essence. So if you are training for fat loss, wouldn’t it make sense to do so in a time-efficient manner?
Note that in the hypothetical scenario, LISS Ned was spending much more time in the gym than HIIT Fred, even though they were expending the same amount of calories, thus putting them in the same caloric deficit. This is an often-overlooked, common sense kind of thing when it comes to training: Don’t want to spend as much time in the gym? Work harder for less time. Don’t want to do the hard stuff? Looks like you’ll just have to dial back the intensity and stay in the gym longer. For a lot of people, the trade-off of more effort for less time is well worth it.
Don’t get me wrong, I’m not trying to paint the picture that all lower-intensity endurance-type work is easy. Talking to anyone who has ran a marathon or finished an Ironman will tell you otherwise. But those things take a ton of time to complete, enormous amounts of time to train for, and are much more performance-based anyway. If I explained to the average person that they could still drop body fat, improve their blood markers, and decrease morbidity without ever having to do a marathon or Ironman, that would probably be good enough for them. Nobody with any sense really signs up for those kind of competitions just to “help them lean out a bit” or “raise their HDL a few points.”
Personally, (when the world is in its normal state as it was 3 months ago) I don’t have the need to do much conditioning to hit a calorie deficit because I’m up walking around the majority of my day. Combined with routine resistance training, I only have to modify my diet little by little over time to hit my necessary numbers to lose fat. However, working from home has drastically changed circumstances for me, just as it has for so many others. I no longer come close to my usual daily average step count, even while taking the dog for long walks every chance I get. Therefore, because I value my free time, I opt for doing more HIIT workouts to help me burn the calories necessary for me to gradually drop body fat. Theoretically, I could just skip any kind of conditioning altogether and just continue to pull calories from my diet, but I like to eat without total misery and I enjoy building up some cardiorespiratory fitness in the process. Besides, I can’t train normally anyway, so what am I going to do? Just not train?
Other Considerations
Since this post may seem a little too pro-HIIT by now, I should probably mention some caveats…
- Not everyone should start with HIIT. If you are coming off of a serious injury or have other physical limitations, or haven’t worked out a day in your life, don’t start with workouts that you see the reigning CrossFit Games champion doing on Instagram. In my opinion, this is actually where a lot of misguided CrossFit gyms go wrong, feeding new untrained members to the sharks by putting them through high-difficulty “WODs” and wondering why they get spit out injured, never to return. If you fit in this beginner demographic, you’d be better off starting with a very basic strength linear progression paired with very light conditioning and leaving the HIIT for later on down the road.
- HIIT should not replace serious strength training. If you keep strength as a high priority, and you are still able to continue your strength training normally, do it. HIIT will give you a great conditioning effect and you can still supplement your strength training with it… to an extent (I’ll get to that next). But even though HIIT usually includes some higher-rep resistance exercises, that doesn’t mean they make great replacements for heavier, low-rep, multi-joint lifts. For instance, if pushups are really easy for you, doing hundreds of them may help preserve your upper body muscle mass (still a good thing), but all those pushups don’t require anything close to the same neuromuscular demand as heavy sets of 5 in the Bench Press with 200-300 lbs. As with many other exercise examples, the physiological stimuli and resulting adaptations are just too far apart to think that they can be interchangeable. If you’re in my boat and can’t resume your normal strength training, just try to pick exercises that allow to load as heavy as you can and just focus on preserving muscle mass for now… possibly while getting lean so that you can accompany your future normal strength training with a hypercaloric diet to increase its effectiveness…? Worth some thought, I think.
- HIIT yields a relatively higher amount of systemic fatigue. Due to the higher intensity of the work done with HIIT, along with the fact that said work is usually also more dynamic and high-impact, HIIT training usually takes longer to recover from compared to LISS training. This is especially important to note if you are trying to supplement your strength training with HIIT, as it’s easy to begin pouring progress out of your strength workouts as just quickly as you pour progress in to your HIIT workouts. As with most things, trying to greatly improve multiple qualities at once often just leads to mediocrity or stagnation in all qualities. If you’re still strength training but want to lose some body fat, do so slowly and try to do so through diet modification first. If you want to introduce some HIIT work, do so gradually and start with the minimum effective dose. If you soon find yourself unable to recover adequately between strength workouts, you may want to consider swapping out the HIIT for more LISS-style conditioning, which will likely take more time to do, but will also assuredly incur less fatigue, thus having less influence on your strength workouts.
- It’s easy for HIIT to turn into random exercising. I think that it’s important to keep structured training from turning into just exercising, in that you still need to keep a clear goal and take steps to work towards that goal by tracking quantifiable progress. Because HIIT has a tendency to have so much variation included, it’s easy to get lost in the weeds and find yourself doing a workout one day and not returning to it for several weeks because everything has been made up on the spot. Have a plan and have a few strategies in mind for charting progress. Add a round each week. Do a more difficult variation of an exercise each month. Make a workout a challenge against time and push yourself to keep a faster pace each week. Variation is nice but it can quickly morph into a mess of imperceptible randomness if you don’t lay down some parameters first. Besides, being able to look at your own data and know that you are objectively improving feels much nicer.
Recap
- Given the current circumstances, many people have switched to doing HIIT-style workouts, in most cases likely due to their psychological appeal, although that’s not inherently a bad thing.
- Both HIIT and LISS can be effective strategies for fat loss, given that they are successful in helping someone consistently meet their necessary caloric deficit. There is nothing magic about either methodology that trumps the overarching law of calorie balance.
- The main advantage of HIIT is the fact that it can burn the same amount of calories as LISS, but in much less time. There is also the benefit of HIIT likely helping to spare more muscle mass during the fat loss process due its usual amount of resistance-based exercises.
- Not everyone should jump straight into a HIIT program, but if you choose to, you need to be aware of its possible effects on other training goals, along with having a strategy and means for logically tracking progression.
Strength Scrolls 