Why do you workout?

Is it to feel good? Lose body fat? Stay strong? Stay competitive? Win an event? Do something healthy with your buddies? Reverse or prevent chronic illness? Whatever your reason, there's almost no well-rounded, balanced exercise program that can be complete without high intensity interval training (HIIT). Short, sweet, and painful, HIIT workouts are beloved by the fitness industry and can accelerate your fat loss.

Keep reading to learn why you should prioritize HIIT in your training routine—and how to optimize its impact.

Why is HIIT Such a Hit for Health and Fitness?

A typical HIIT workout involves short bursts of really hard work mixed in with some easy-peasy steadier-state cardio. The secret sauce of this training methodology is right in its name:

• High intensity: hard work! Sprint portions of HIIT sessions are usually done at or near full effort, or let's say around 90% or more of your max heart rate (max heart rate = 220 minus your age). At an "all out" effort, your body is using a TON of oxygen and you should feel very uncomfortable—you shouldn't be able to talk nor sing along to whatever jams you've got playing in your headphones.
• Interval: sprint periods are short and interspersed between periods of slow easy effort or even full rest. This gives your body time to recover so you can keep the intensity high during the all out portions of the workout.

Pretty simple, right? And the great news is an effective HIIT workout can last literally 15 minutes or less and done no more than 2 to 3 times per week. Challenging? Of course. Doable? Yes—even for the most time-strapped among us. Now here's why they're worth the effort:

HIIT-style workouts are superstars for fat loss (along with improved stamina, power, and endurance). A leading theory as to why is that HIIT workouts trigger a physiological phenomenon known as excess post-exercise oxygen consumption (EPOC). EPOC is a period of time following strenuous physical activity during which your body burns oxygen at a faster rate. To understand why this matters, check out this analogy from the American Council on Exercise:

You're on a road trip. After a few hours, you pull into a rest stop to stretch your legs and use the bathroom (because we know you're staying well-hydrated, right?!). When you turn your car off, what happens to your engine? That's right—it stays warm for a while. It doesn't just cool down immediately. Instead, it takes some time get back to its "resting" state.

Now, your body immediately post-exercise behaves very similarly. It takes an extended amount of time to cool down. Now during this time, as your body tries to get back to its resting state (homeostasis), your metabolism is UP and you're burning through oxygen faster than normal. This requires energy (aka calories). In other words: you're burning more calories than you would normally at true "rest," even when your workout is over!

The EPOC effect can happen after almost any type of workout, including low-intensity steady state cardio, heavy resistance training, and HIIT. But research shows that HIIT is typically the MOST effective at eliciting EPOC—meaning it can help you burn more calories and therefore lose more body fat.

If you're surprised that a workout as short as 10-15 minutes performed just 2 to 3 times per week can be so beneficial, jut remember what the first part of the HIIT acronym means: "high intensity." These workouts NEED to be relatively short because otherwise you wouldn't be able to maintain the high level of intensity needed to help your body use more oxygen and maximize the EPOC effect. If you were to spend too long operating at "high intensity," sooner or later your intensity level will just drop, and you'll no longer be tapping into the correct energy system. So, short and sweet is best.

One SUPER important disclaimer: "high intensity" is RELATIVE to your body and your physical capability! Push yourself, but be smart about it. Don't go to the point where you start to lose proper form or put yourself at risk for injury, mm'k?

5 HIIT Templates To Try

Aside from their overall effectiveness and efficiency—yes, you can get in and out of the gym in less than 30 minutes and have a butt-kicking workout—HIIT workouts are nearly endless in their design and functionality. To give you some inspiration, try these four templates, but feel free to experiment with other ideas:

Tabata

The Tabata workout is 8 rounds of 20 seconds of all out effort followed by 10 seconds of rest. It's named after a Japanese exercise physiologist Dr. Izumi Tabata and is probably one of the most well-known styles of HIIT.

Here's what to do:

• Start a timer.
• In the first 20 seconds, sprint as hard as you can.
• In the next 10 seconds, rest completely.
• Repeat 8 times.

Feel free to double check our math on this, but one full Tabata workout is just 4 minutes long!

AMRAP

AMRAP means as many reps (or rounds) as possible. This is a popular type of circuit training that can be used for HIIT as well as lower-intensity steady state cardio. For HIIT, try doing AMRAP "clusters." Here's what to do:

• Start your timer.
• Do a 5 minute AMRAP of your given exercise or movements. Examples: a circuit of 5 TRX rows, 5 push ups, and 10 squats or as many meters as possible on a rowing machine.
• Rest for 3 to 5 minutes.
• Repeat this "cluster" of a 5 minute AMRAP plust a 3-5 minute rest around 2 to 3 times.

OTM/EMOM

On the minute (OTM) or every minute on the minute (EMOM) workouts are fun ways to challenge yourself to go hard, because the faster you go, the more rest you get! Here's how it works:

• Start your timer.
• At the top of every minute, do a prescribed amount of work as quickly as you can. Examples: 1 40-yard dash, 10 burpees, 15 air squats, etc.
• When you're done with the work, simply rest the remainder of the minute.
• When the next minute comes around, repeat the work again. You can also opt to switch in different movements. For instance, do 1 40-yard dash on the even minutes, and 10 burpees on the odd minutes.
• Repeat anywhere from 8-12ish times (don't do too many rounds since you're trying to keep up the intensity).

Fartlek

Um...fart-WHAT?

Originating in Sweden in the 1930's, Fartlek means "speed play" and we honestly can't think of a more appropriate translation. This HIIT-style running is excellent for building stamina and involves a mix of steady state cardio with high speed sprinting peppered in to keep things interesting. In other word: you intermittently tax the anaerobic system and then, instead of stopping like you may do in other HIIT workouts, continue training the aerobic system during your "rest."

There's not one specific Fartlek template to follow—it's fair game to head out of for a 15 to 20 minute run and just make up your own—but if you want an idea here's a good one to try:

• Find an open football field or soccer field (even a basketball court can work).
• Jog around the perimeter of the entire field once, starting in one corner.
• On the second lap, jog three sides and sprint the fourth.
• On the third lap, jog two sides and sprint the third and fourth.
• On the fourth lap, jog one side and sprint the second, third, and fourth.
• On the fifth lap, sprint around the entire perimeter of the field as fast you as you can.
• Sixth lap is a cool down, and all laps are run in succession (no rest breaks between).

Other ideas are sprinting telephone poles on a road run or doing something like a 3 minute hard/1 minute easy pace for 5-7 rounds. While Fartlek workouts are sometimes a bit longer than other traditional HIIT sessions, they're still super effective and can be a fun and creative way to get more of that intermittent sprinting into your life.

Getting the Most out of Your HIIT Workout (or Any Workout, For That Matter)

Not a running fan? You don't have to rely just on tracks and treadmills for these HIIT workouts. Assuming your form is good, you can also try movements like:

• Machines: assault bike, upright bike, recumbent bike, elliptical, VersaClimber, stepmill, stair climber, rower, ski erg
• Bodyweight movements: burpees, jumping squats, air squats, lunges, sit ups, mountain climbers, jumping jacks, step-ups
• Moves with equipment: wall ball shots, jump rope, dumbbell or barbell thrusters or clean and jerks, kettlebell swings or snatches, sled pulls, sled pushes, battle ropes

In other words, your choices are about as numerous as your repertoire of exercise moves! Just be sure to pick stuff you're comfortable doing, since you'll be working at such a high intensity. And if you're using weights like dumbbells, kettlebells, or barbells, keep them light so you don't hit muscular fatigue.

Another important step for maximizing your HIIT workouts is warming up properly. Think of it this way: your heart rate should already be elevated and you should already be a little sweaty by the time you hit "start" on your workout timer. Otherwise, you'd waste time during the workout itself by simply trying to get your heart rate up enough

Lastly, post-workout protein is a must for optimizing your body's recovery after exercise. Research doesn't give us exact figures, but you should generally try to eat about 20 to 40 grams of high quality protein within 30 to 90 minutes following your session. Our tip? Put some portable and easy-to-digest protein in your bag, like a high quality protein shake and some protein nut butter.