High intensity interval training made headlines in the 2010s with one specific claim: that short bursts of hard work can give the same aerobic benefits as longer sessions of jogging or cycling. But the HIIT videos you can stream today have very little to do with the original model, and many of them aren’t worth your time.
Before we break down the difference, I want to make something clear: If you love doing videos labelled “HIIT,” and they’re part of an exercise routine that makes you genuinely happy, keep on doing them. I’m not trying to take away a thing that you love.
But if you’re doing them because you feel they’re the best way to achieve your goals, or because a trainer or influencer tells you that they’ll burn a ton of calories or build your booty, we need to sit down for a little intervention.
What is real HIIT?
High intensity interval training was born as a buzzword after exercise scientists noticed that people got better at the Wingate test every time they took it. The Wingate protocol calls for people to pedal all-out, at a high resistance, for a pukeworthy 30 seconds. Then you get to rest for four minutes, and do it again.
After further experiments, researchers figured out that the benefits they saw, including increased aerobic fitness, could be triggered by other rest/work combinations. The Tabata protocol, again done on a research-grade exercise bike (“cycle ergometer,” they call it) is 20 seconds of work and 10 seconds of rest, repeated for just four minutes in total.
These are not workouts that people do for fun. Everyone who I’ve seen recount the experience has said that it was complete agony. The scientists often note that people can rarely push themselves hard enough to replicate these protocols on their own.
So Martin Gibala, one of the researchers who popularised the concept of HIIT, worked to find a version of the protocol that normal humans could do on their own, and that wouldn’t leave them so pooped they were scared to come back. His conclusion: one minute work/one minute rest was the sweet spot, and you could do it while cycling, jogging, or doing other aerobic activities. Interval workouts boomed in popularity, using a variety of work/rest intervals.
How do newer HIIT videos compare?
The term HIIT didn’t just get watered down; it mutated.
When it began, HIIT was about getting more results in less time, so it built a reputation as being more efficient, maybe even superior to things like jogging. And since you don’t need a bike to do HIIT, trainers ran with that idea and started applying the term to literally anything they could think of. Bodyweight squats? Bicep curls? Sure, why not. As a result, these days HIIT means something more like “a workout with a timer counting down in the corner.”
HIIT’s popularity had been building for years when lockdown hit, and from there it exploded. If you’re a trainer or influencer trying to come up with something you can easily film, you’ll probably gravitate to no-equipment home workouts. And to make them sound exciting, you’ll call them HIIT.
The label “HIIT” on a bodyweight workout, I suspect, is supposed to translate as “good enough.” Yeah, you’re doing a few lunges in your living room, but the trainer wants you to think it’s just as good as anything you could get from a boutique studio or a full-featured gym. Maybe better.
You can tell how far removed these workouts are from real HIIT by judging the promises they make. Are they saying they’ll improve your VO2max, which was one of the original benefits noted? They won’t — not usually. Let’s do a quick rundown:
Do they burn a lot of calories? Not necessarily, but it depends on the workout. The longer the workout and the more out of breath you are, the more calories you’re burning. The truth is, 20 minutes of “HIIT” often doesn’t burn any more than 20 minutes of medium intensity exercise like jogging.
Do they burn more calories after the workout? In theory, your body keeps burning calories after a hard workout session. But there are two caveats: First, this is only significant when the workout is really intense. And second, after you do a hard workout, your body often wants to conserve calories for the rest of the day, so it all evens out while you’re lying on the couch. Even Gibala has said that afterburn is overstated.
Do they help you lose weight? Diet matters more to weight loss than the amount of exercise you do, much less the specific type. Exercise can help a little bit with the “calories burned” side of the equation (as long as it doesn’t make you hungrier, which it sometimes does), but now we’re back to the reality that HIIT workouts don’t have any special advantage in burning calories.
Do they build muscle? Maybe a little, but they won’t get you the booty/arms/whatever of your dreams. High repetitions of light weights will only build muscle if you’re going to failure, which means you’ll need to rest a minute before you do another exercise with the same body part. If your “HIIT” workout allows for this, great! But pretty soon you’ll be strong enough that the workout isn’t challenging your muscles enough to grow. You really do need to train increasingly heavy if you want to build muscles.
How do I know if an HIIT video is actually good?
First, ask yourself why you’re doing the video. Do you want to increase your aerobic fitness? Then evaluate whether following the video actually gets you out of breath and allows adequate rest for you to do it again. Do you want to build muscle? Then evaluate whether the video actually challenges your muscles.
As I mentioned above, sometimes we do “HIIT” videos not for any specific outcome, but because it feels good to move our bodies and we like the moves in the video. This is fine and good and it definitely counts toward the 75 to 150 minutes of exercise you should be getting weekly. But if you have specific goals, seek out the best ways to achieve them. Chances are, there’s something out there that’s better for you than yet another “HIIT” video.