Everything you need to know about HIIT

Everything you need to know about HIIT

By Eric Velazquez

Maximize your fat-burning efficiency with high-intensity interval training.

It’s been a while since high-intensity interval training (HIIT) stormed onto the fitness scene and began its dogged takeover of the cardio universe. One study at a time, HIIT knocked steady-state cardio off its long-held throne, becoming the most relied-upon method for burning unwanted body fat in gyms everywhere.

 But taking it to the max, as any HIIT workout requires, is serious business. When dialing up the intensity, it’s important to properly prepare for the fat-fighting agenda you’ve so brazenly mapped out and to perform it with the same purpose-driven enthusiasm you pour into your sets at the squat rack.

Much has been made about the effectiveness of intervals over traditional cardio, but there’s been less attention paid to the mechanics of HIIT. How much is too much? How do I gauge intensity? What work-to-rest ratio is most effective? For as much research as the lab coats have managed to drop in our lap, they’ve still left us with questions.

Justin Grinnell, C.S.C.S., a performance coach and owner of State of Fitness in Michigan, knows that connecting the dots on HIIT will make it an even more efficient protocol for torching fat.

“HIIT is a method of conditioning that uses alternating periods of work and rest,” says Grinnell. “It’s great because it can be done by using various modalities, such as an Airdyne bike, a treadmill, a Concept2 rower, a heavy bag, a StepMill, or by just hitting the pavement and sprinting. This type of training is not only being used by athletes to improve conditioning but also by trainers and their clients as one of the best methods for fat loss and conditioning. With our busy lifestyles, who has time to do 40–60 minutes of aerobic training? The scientific data now show that less is better when it comes to fat loss—you just have to know how to do it right.”

HIIT is hard; and while we have no intention of making it easier, these insights can help make it much more effective.


HIIT really describes a protocol, a workout prescription more about application than exercise selection. Working in short, intense bursts of activity holds greater benefit than droning about at a slow pace doing anything else—and that holds true whether you’re rowing, boxing, jumping rope, or swimming. Most of the research, however, has been done on sprinting, which, judging by treadmill row at rush hour, is the most relatable method of cardio for most gym-goers.

So while many of the same benefits can be had adding HIIT stylings to your next workout of choice, sprinting is a sure bet for max results.

“Sprinting workouts aren’t effective just for fat loss but also for muscle growth,” Grinnell says. “Elite sprinters are generally very muscular and lean because the conditions required for muscle growth are all present during sprinting— general overload, volume fatigue, and high concentric contractions.”

And it just so happens that most guys would rather look like a gold medal sprinter than an emaciated distance runner.

Bottom Line

Choose the HIIT activity that you’ll do consistently. Ideally, you should shoot for movements that are full body in nature, such as sprinting (where most of the research has been done), swimming, or rowing.


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