HIIT vs Interval Training

What’s the difference? Is there a difference?

That’s the basis of a conversation I had with a friend the other day…She said she had been doing 45 minute HIIT (High Intensity Interval Training) workouts…well, that was my first clue that she was a bit off in her definition of HIIT. You see she, like many I suspect, was thinking interval training and HIIT training were one in the same. They’re not. Yes, HIIT is interval training but not all interval training qualifies as HIIT. That is an important distinction, especially when it comes to attaining all the benefits of HIIT that you have no doubt read about (reduced training time, increased metabolism, faster fat loss, increased muscle mass, etc.)

Interval training is any type of workout where you vary the intensity for short periods of time. One of my favorite (running) interval workouts is 1 minute easy (a 3 on a scale of 1-10 with 1 being standing still and 10 being “running for your life”) followed by 2 minutes harder (a 7 on a scale of 1-10) and repeating that for 10 rounds for a 30 minute workout. Is that a hard workout? Absolutely. Is it a great workout? Definitely. But is it an HIIT workout? No.

True HIIT interval training is similar in the “rest” department…your rest is anywhere from a 1-3 on the 1-10 scale, but your interval is an all-out, run for your life 10 on that scale. That would the “high intensity” in the name. The reality is that the term really should stand for “highest intensity” interval training because that is what you need to realize the benefits of HIIT. And since HIIT is a “give it all you’ve got, cannot possibly go any harder” effort, there is no way you could sustain it for 45 minutes! Seriously, if you are giving it everything you have, you will flame out after 10-15 minutes… maybe 20 but that is arguable.

So often people get stuck in the “45-60 minute workout” mindset that came to us courtesy of the aerobically enhanced ’80s and ’90s, and to this day there are tons of people who, when they don’t have that 60 minute block of time, will just skip working out altogether because they “don’t have time for a good one.” Then there are those that sort of get the whole “HIIT takes less time” theory, but then they still try to go the 45 minutes or so…that’s great in that they may be doing a fantastic interval workout, but they’re not doing HIIT, so the benefits, while good, are not what they could be with a 10-15 minute true HIIT workout. But do keep in mind, that you can overdo it on the HIIT workouts…for most, 1-2 HIIT workouts a week is beneficial without risking injury.

One of the most well-known, and most popular HIIT workouts is the Tabata Protocol. Tabatas are 20 seconds all out followed by 10 seconds of rest, repeated for 8 rounds (4 total minutes). Done correctly, you can barely stand after those 4 minutes! There are many other versions of HIIT, like the partner 30/30s: you go all out for 30 seconds while I rest, then I go all out for 30 while you rest, etc. Many minutes in a row of that and you’re toast, and that’s the point. It’s the “toasting” during the workout that requires all the extra energy for repair and replenishment after the workout (for 24-48 hours).