High-intensity interval training (AKA “HIIT”) has been a popular training method for years. It’s effective and time-efficient. But, as time has gone on, the methods you see being labeled as “HIIT” are getting farther away from the science that proved the effectiveness of these types of routines.
Just because the high intensity is good, doesn’t mean adding more and more work is better.
The biggest problem with HIIT workouts is that people took a great concept (higher intensity, less rest) and destroyed the execution.
The mindset looks something like this:
“If four minutes is great, then eight minutes must be incredible. And if eight minutes is incredible, then 16 minutes must be mind-blowing.”
This is the opposite of what you want to do. Adding more time does not make all workouts more effective. And, with HIIT, you could easily argue it could reduce the effectiveness of the training.
Why HIIT Workouts Are So Effective
The name of the game is efficiency. There are many ways to train, but scientists are fascinated by high-intensity interval workouts because, when done correctly, you can see great benefits in less time.
The key with good HIIT programming is doing everything you can to maximize intensity. It’s that intensity that enables you to keep the workouts shorter and experience benefits like muscle building, fat loss, and cardiovascular improvements that you typically see in longer workouts.
But, if you don’t set up your workouts in a way that keeps intensity high, then you start to take away from the power of HIIT.
In general, HIIT workouts are characterized by the following:
- Go hard (work at a high intensity, either heavy weights or lots of reps).
What makes HIIT so effective is the exercise-to-rest ratio. As decorated strength coach Robert Dos Remedios explains in this blog post, a lot of the most popular training protocols are totally backward when it comes to their work-rest ratio.
Translation: People train for way too long of a period, followed by far too little rest.
Coach Dos explains that for a truly all-out effort, you should rest for as much as 5-6 times the time you spent working. When you train for longer periods while resting for shorter ones, the training winds up being more of a cardio/aerobic challenge — which is okay if that’s your goal.
When you go for too long with too short of rest, you’re likely to decrease the intensity of your work, which is the whole point of high-intensity training.
What is the Best HIIT Workout?
If you want HIIT to work for your body (and schedule) and lead to body transformation and health benefits (HIIT workouts are also shown to improve cognition), then shorter rest periods will necessitate shorter workouts. This is all done to maximize intensity and results. Long HIIT workouts with short rest periods are more likely to lead to burnout and not get the desired effects.
In other words, your “work” periods will influence your rest periods. Keep the work short per Dos Remedios’s recommendations, and as the interval work time increases, make sure your rest increases as well.
An ideal work-to-rest ratio for all-out high-intensity intervals could be:
- 10 seconds of work, followed by 50 seconds of rest
- 20 seconds of work, followed by 100 seconds of rest
- 30 seconds of work, followed by 150 seconds of rest
Now, that’s not to say you can’t do more common intervals like 20 seconds of work followed by 40 seconds of rest.
If you do that, either realize that later sets will be lower intensity, or make sure you do fewer total sets in order to maintain your intensity.
After all (and we can’t stress this enough), the key to HIIT is the intensity. Push your body to maximum output, rest for just enough time to keep that intensity at its highest, and then get back to work.
How Long Should a HIIT Workout Be?
So, what’s the sweet spot? Everyone is going to be a little different based on body type, training experience, and goals. And there are really two important aspects: how many days per week you should do high-intensity training and how many sets you should perform per session.
Craig Marker, Ph.D., an associate professor at Mercer University, explains that you should stop if you are noticing a drop off in your performance from set to set.
“I stop most of my athletes at seven sets as it is difficult to maintain that pace for the full eight. Tabata’s team was working with elite athletes. For the everyday athlete, I might even suggest fewer sets, like three to five.” (You can read more about his approach here).
How Often Should You Do HIIT Workouts?
Because these workouts take more time to recover, it’s recommended that you do a HIIT workout anywhere from 1-3 times per week, depending on the overall volume of your training.
For example, if you’re weight training 4-5 times per week, you’ll respond better if you only do an additional 1-2 HIIT sessions per week. Otherwise, you’ll never recover properly and week-over-week you won’t see as much progress with your training or changes to your body.
If you only train with weights 2-3 times per week, then it’s possible for you to add 2-3 sessions of HIIT per week.
How To Do A HIIT Workout
Using the guidelines above for frequency, here’s how you can build your own HIIT workout using the exercises of your choice. Follow this 2-step process, and then limit your work sets to 4 to 8 rounds, based on your level of fitness.
Step 1: Select The Best HIIT Exercises
As the name would suggest, HIIT workouts should be something that allows you to push at a very high intensity.
If you choose to walk, then you must be able to sprint. If you want to bike, then pedal harder (if you can increase the resistance) or faster. If you’re swimming, swim faster. And, if you’re lifting weights, you’re picking a weight that you can lift for about six reps or where you can move quickly and explosively (think medicine ball slams).
Here are exercises you can pick from (many more exist) to create your HIIT workout:
- Kettlebell swings
- Versaclimber or stair-stepper
- Jump rope
- Tire flips
- Jump lunges
- Med ball slams
- Deadlifts or squats
Step 2: Select How Long to Make Your HIIT Workout Last
- 10 seconds of high-intensity work.
- 50 seconds of rest or low-intensity work.
- Repeat for 4-8 rounds.
- 20 seconds of high-intensity work.
- 100 seconds of rest or low-intensity work.
- Repeat for 4-8 rounds.
Step 3: Recover
Remember, intensity isn’t just about how much time you have to recover during a workout, it’s also what you do between workouts. To maintain intensity during your workout, remember to focus on resting 5-6 times as long as your work sets. And, don’t perform HIIT workouts every day because, at some point, your overall intensity will decrease, you won’t make progress from one training session to the next, and that will limit your results.
Now Go Get Your Sweat On
We’ve laid out why high-intensity interval training is effective, what the best HIIT workout practices are, and provided examples of some of our favorite exercises. Remember, the key to proper HIIT training is maintaining a high level of intensity for the entire workout.
Have questions? Share them in the comments below.
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Adam Bornstein is a New York Times bestselling author and, according to The Huffington Post, “one of the most inspiring sources in all of health and fitness.” An award-winning writer and editor, Bornstein was the Fitness and Nutrition editor for Men’s Health, Editorial Director at LIVESTRONG.com, and a columnist for SHAPE, Men’s Fitness, and Muscle & Fitness. He’s also a nutrition and fitness advisor for LeBron James, Cindy Crawford, Lindsey Vonn, and Arnold Schwarzenegger. His work has been featured in dozens of publications, including The New York Times, Fast Company, ESPN, and GQ, and he’s appeared on Good Morning America, The Today Show, E! News, and The Cheddar.