🗂️Keep in Mind How 'Sprint Interval Training' Compares to HIIT (and How to Do It)

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Sprint interval training, or SIT, is super trendy right now. It’s a great way to improve your running speed and to get in a hard interval workout, and I’ll explain exactly how. But I also need to clear up this silly question about whether it’s “better than” HIIT (or high-intensity interval training). SIT is, in fact, a type of HIIT.

What is SIT?​

Sprint interval training refers to exercise routines where you run as hard as you possibly can (or nearly as hard) for a short time, typically 30 seconds. A SIT workout usually looks something like this:

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  Warm up with walking and/or easy jogging for 10 to 15 minutes.
  
  
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  Run 30 seconds as hard as you can.
  
  
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  Recover (walk or rest) for three to five minutes.
  
  
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  Repeat the above steps anywhere from four to 10 times.
  
  
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  Cool down with more walking or easy jogging—for, say, five to 10 minutes.
  

The benefits of SIT include improved running economy (basically, your body gets more efficient at the running motion) and improved time in running races. SIT has not been found to increase your VO2max any better than steady-state training, or any better than HIIT. For example, this study found no significant difference in VO2max between SIT training and a control group that did steady state training (both improved), but it did find that the SIT group was better at sprinting. Not surprising, when you think about it.

Here is some data from a recent SIT workout I did. I wanted to get in five miles for the day, so I warmed up for 15 minutes and cooled down for about the same, and in between I did 10 intervals of 30 seconds each, with three minutes’ recovery. (I thought about doing four minutes, but I only had about an hour to get that workout in, so I opted to be a bit more efficient.) The sprints were hard, but the recovery gave me plenty of time to feel ready to go again.

Credit: Beth Skwarecki

What is HIIT?​

As I’ve written (or, to be honest, ranted) before, HIIT started as a catch-all term for hard interval workouts, and has mutated into a marketing buzzword that signifies the general idea of hard work in a short timeframe.

HIIT stands for high intensity interval training, and it includes all kinds of different interval schemes. Here are some of the “classic” HIIT workouts from the scientific literature:

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  Wingate sprints: 30 seconds all-out, followed by 4ish minutes of rest, repeated several times. (These were originally done on a research-grade exercise bike.)
  
  
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  Tabatas: Four minutes of 20-second all out sprints, with just 10 seconds between each one. These, too, were originally done on a bike, and you do the whole block once, not multiple times.
  
  
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  60/60: One minute hard, one minute easy, then repeat
  

Scientific articles that review the results of HIIT tend to have trouble coming up with a definition, since the term has been used so many different ways. This study has a table with examples, including the ones above, plus basketball players’ shuttle runs and swimmers’ 50-meter intervals. This one defined HIIT as anything where the work intervals were four minutes’ duration or less.

Did you notice something? Those Wingate intervals? Yep, that’s the same type of workout people are now calling SIT. SIT is a type of HIIT.

Is SIT or HIIT better for fat loss?​

Neither is better. SIT is a type of HIIT, anyway. If you want to change your body composition, the exact type of exercise doesn’t matter much, as long as you are doing some kind of strength training to preserve or build muscle. The difference between your calorie intake and your calorie burn is what determines how much fat you lose. It doesn’t really matter how you burn your calories.

The term “SIT” is being misused on social media​

SIT should be a little easier to understand than HIIT, since it’s one specific family of workouts. But as I browsed TikTok and other social media, I found people using SIT to refer to non-SIT protocols like 20 seconds work, 10 seconds rest, for five rounds. That’s not SIT at all. I also found a “SIT” workout that involved 20 seconds of kettlebell swings, 20 seconds of thrusters, and 30 seconds of burpees. That’s not even sprinting! Take all these social media workouts with a grain of salt, especially when they make big promises about weight loss or muscle gain. SIT isn’t some magic secret to getting a fitness influencer body; it’s just a nice, intense workout that benefits your running.
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