HIIT- What, Why & How?

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If you’re stuck in the 40 minute cruise control elliptical routine daily, then this is going to be an eye opening article for you. Anyone who knows me, or who has seen me train, knows that my approach is one of sheer intensity. I want to WORK when I get to the gym, I want to sweat, I want to walk out of there sore, satisfied, exhausted, and yet extremely euphoric from having completed a killer workout. This desire for intensity stems not just from my weight workouts but from my cardio as well, which is why I’m a staunch advocate of HIIT cardiovascular workouts as an integral part of my training protocol, and the training regimes of my clients as well.

I’m well aware that there are bodies on both sides of the fence when it comes to HIIT and whether or not it’s effective. For every person, such as myself, who advocates in favor of HIIT workouts, there is an equal number of people who will swear that steady state, low intensity cardio is best.  I will say that I’m a firm believer that HIIT could and should be a facet of everyone’s routine, whether small or large scale. But before I get into why you should incorporate HIIT and how, I need to explain what it is, and how it found its way into the hot spot of trends as far as fitness goes.

ripped hiit


I hit up good old Wikipedia for a textbook definition of “what” HIIT is. Wikipedia defines HIIT as the following; “High-intensity interval training (HIIT), also called High-Intensity Intermittent Exercise (HIIE) or sprint interval training, is an enhanced form of interval training, an exercise strategy alternating periods of short intense anaerobic exercise with less-intense recovery periods. HIIT is a form of cardiovascular exercise. Usual HIIT sessions may vary from 9–20 minutes. These short, intense workouts provide improved athletic capacity and condition, improved glucose metabolism and improved fat burning”

HIIT is fascinating, it’s a novel form of cardio that couples intervals of high-intensity exercise (such as sprinting) with intervals of either low-intensity exercise (such as walking at a slow pace) or complete rest. This style is a departure from continuous steady-state (slow and steady) cardio that most people do at a moderate intensity for 30-to-60 minutes. Typically HIIT has been seen in the training programs of athletes, not the average man or woman, or even physique athlete. HIIT was developed decades ago by track coaches to better prepare runners, which is part of why it’s so strongly associated with athletic performance rather then someone looking to simply shed bodyfat. At the time it was known by the oh-so-catchy name of “Fartlek” training, the conjoining of the Swedish words for speed (fart) and play (lek). So essentially HIIT means “speed play,” which is a good description of what the training method is all about.

HIIT Training, Sprints, Michael Johnson


HIIT is for everyone, at least in my opinion. Whether you perform only one or two HIIT sessions a week or incorporate HIIT into your program on a much broader scale, if you’re concerned with how you look on the beach, you’re a bodybuilder or a figure athlete, you’re looking to shed bodyfat OR gain muscle- HIIT fits. Period.

What about muscle mass? I’m sure by now you’ve heard that steady state cardio is best for maintaining muscle mass. I beg to differ. Cardio done at a higher intensity for a shorter period of time will not only help you maintain your muscle, but can actually help you build muscle mass. When you train at a slow and steady pace for a longer period of time, you are training your muscle fibers to be more aerobic and have greater endurance- you’re stimulating SLOW twitch muscle fibers. Do you know how muscle fibers adapt to becoming more aerobic and gaining greater endurance? By becoming smaller and weaker! Think about a marathon runner in comparison to a sprinter- think about the physique differences. Distances runners (think steady state long duration cardio) are smaller, thinner, and far less muscular or powerful then the physique of a world class sprinter. By comparison sprinters are compact, muscular, and have a much more dense solid appearance. The reason distance runners look so thin is that the smaller a muscle fiber is, the less time it takes for nutrients to travel within the muscle fiber. This speeds up the rate that the nutrients can be burned for fuel- fuel needed for long runs, bikes, or swims.

HIIT Cardio

Think about it from a common sense perspective. The statement that slow and steady cardio for longer periods of time is best for maintaining muscle mass is similar to saying that curling 5-pound dumbbells for 30 minutes straight will build more muscle than curling 40 pound dumbbells for sets of 10 reps with rest between sets. Food for thought huh? Think about a bodybuilder’s muscles from pulling heavy weight in comparison to the average guy slinging around lighter weights in the gym. Which do you THINK builds more muscle and stimulates fast twitch muscle fibers? The research backs it up as well. I can think of one study completed in New Zealand that demonstrated that HIIT produced MORE testosterone then longer steady state cardio. Since testosterone is critical for boosting muscle size and strength, this means that doing HIIT with greater resistance can aid muscle growth and strength.

What about fat loss? Well if fat loss is your goal, or you simply want to shed the tire around your middle and get in shape for the summer- you’re in luck. HIIT is where it’s at.

The why is pretty simple- the research backs it. HIIT stumbled into the mainstream fitness spotlight for one simple reason- the more research that was done on the method the more people wanted to know about this fat incinerating style of training. One of the first studies to discover that HIIT was more effective for fat loss was done nearly a decade ago in 1994 study by researchers at Laval University (Quebec, Canada). Their report claimed that young men and women who followed a 15-week HIIT program lost significantly more body fat than those following a 20-week continuous steady-state endurance program. This, despite the fact that the steady-state program burned about 15,000 calories more than the HIIT program! This study was shocking- how could HIIT destroy more bodyfat through less training duration and less overall calorie expenditure?

HIIT Cardio

If you haven’t heard of, or read Alwyn Cosgrove’s research articles on how superior HIIT is for fat loss- let me recap. When done PROPERLY (which I’ll get to in a minute) HIIT produces something called EPOC (Excess Post Exercise Oxygen Consumption). What does this mean? Well informally, it refers to “afterburn”, a measurably increased rate of oxygen  intake following strenuous activity intended to erase the body’s “oxygen debt.” EPOC is used in several processes post exercise but the one to note in this article is that EPOC is accompanied by an elevated consumption of fuel. In response to exercise, fat stores are broken down and free fatty acids (FFA) are released into the blood. In recovery, the direct oxidation of free fatty acids as fuel and the energy consuming re-conversion of FFAs back into fat stores both take place.

Studies have shown that EPOC levels post HIIT pop in at 14% compared to the 7% stimulated by steady state cardio.  Now keep in mind this is all with the assumption that HIIT is performed PROPERLY- which tends to be more problematic then most people assume. HIIT is all about intensity. Extreme intensity. Most people assume that interval cardio (alternating speed and intensity intervals) qualifies at HIIT, when in actuality, it does not. Interval cardio should push you into the 65%-85% of your max heart rate range while HIIT on the other hand should be at least 85% of your maximum heart rate. Most people never get the most out of HIIT because they aren’t pushing themselves hard enough. Meaning: never until their muscles burn.




HIIT should be integrated progressively, meaning you should start with work to rest ratios that allow for longer rest periods then work periods. For example, maybe 15 to 60 work to rest ratio. This will allow your body to adjust to the integration of HIIT. This type of training, done properly is VERY intensive and should be treated as any other intense training method- I recommend not doing HIIT on the days you also incorporate intense weight training to allow for recovery.

You can gradually tweak and change your work to rest ratios as your body progresses. So maybe after the first initial 4 weeks performing HIIT, move to 30 seconds intense exercise and 60 seconds rest, then 30 to 30 work to rest ratios and finally 30 to 15 work to rest ratios in which your rest period is shorter than the duration of your work period.

Keep your HIIT workouts short, no longer then 20 minutes in duration. I recommend a good 10 minute warm up. Walk or jog at a very slow pace to encourage blood flow to your muscles and get your body ready for higher intensity activity. Then begin your workout by increasing your speed to a barely sustainable intensity for your fitness level. Alternate that level of intensity with a low intensity recovery period. Alternate the high intensity segments with low intensity segments for the duration of your workout.

Plan to do HIIT just two times per week on non-consecutive days, at least to begin. Allow your muscles to rest at least 48 hours between sessions so they can repair and grow stronger. As you become stronger, add in a third session per week if you desire.