How “Sprint Interval Training” Compares to HIIT (and How to Do It)
Sprint interval training, or SIT, is all the rage right now. This is a great way to improve your running speed and do intense interval training, and I’ll explain how. But I also need to clear up this stupid question about whether it’s “better” than HIIT (or high-intensity interval training). SIT is essentially a variation of HIIT.
What is SIT?
Sprint interval training is an exercise where you run at maximum intensity (or nearly so) for a short time, usually 30 seconds. SIT training usually looks something like this:
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Warm up by walking and/or light jogging for 10 to 15 minutes.
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Run as hard as you can for 30 seconds.
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Recover (walk or rest) for three to five minutes.
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Repeat the above steps four to 10 times.
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Cool down by walking or light jogging for, say, five to ten minutes.
Benefits of SIT include improved running economy (essentially, your body becomes more efficient in the running motion) and improved running times. SIT has not been found to increase your VO2max any better than continuous training, or any better than HIIT . For example, this study found no significant difference in VO2max between SIT training and a control group that performed steady-state training (both improved), but did find that the SIT group was better at sprinting. Not surprising when you think about it.
Here’s some data from my recent SIT workout. I wanted to run five miles in a day, so I warmed up for 15 minutes and cooled down for about the same amount of time, and in between I did 10 intervals of 30 seconds each with a three-minute recovery. (I thought about going for a four-minute run, but I only had about an hour for that workout, so I decided to be a little more efficient.) The sprints were hard, but the recovery gave me enough time to feel ready to go again.
What is HIIT?
As I’ve written (or, frankly, ranted) before , HIIT began as a catch-all term for hard interval training and then evolved into a marketing buzzword for the general idea of working hard in a short amount of time.
HIIT stands for high-intensity interval training and includes a variety of interval patterns. Here are some of the “classic” HIIT workouts from the scientific literature:
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Wingate sprint : 30 seconds at full power, then 4 minutes rest, repeated several times. (They were originally performed on a research-grade exercise bike.)
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Tabatas : Four minutes of 20-second sprints with just 10 seconds between each. Initially, they were also performed on a bicycle, and you do the entire block once , and not several times.
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60/60 : One minute hard, one minute easy, then repeat.
Scientific articles that discuss the results of HIIT typically have definitional issues because the term has been used in different ways. This study has a table with examples including those above, as well as basketball players’ shuttle runs and swimmers’ 50-meter intervals. It defines HIIT as anything where the intervals are four minutes or less.
Did you notice anything? These Wingate intervals? Yes, this is the same type of training that is now called SIT. SIT is a variation of HIIT.
Which is better for burning fat: SIT or HIIT?
Neither one nor the other is better. In any case, SIT is a form of HIIT. If you want to change your body composition, the exact type of exercise doesn’t really matter, as long as you do some kind of strength training to maintain or build muscle mass. The difference between calorie intake and calorie burn determines how much fat you will lose . It doesn’t really matter how you burn calories.
The term “SIT” is misused on social media
SIT should be a little easier to understand than HIIT since it is one specific family of workouts. But while browsing TikTok and other social media, I found that people are using SIT to refer to non-SIT protocols, such as 20 seconds on, 10 seconds off, for five rounds. This is not SIT at all. I also found a “SIDA” workout that included 20 seconds of kettlebell swings, 20 seconds of thrusters, and 30 seconds of burpees. It’s not even a sprint! Take all those workouts on social media with a grain of salt, especially when they make big promises about weight loss or muscle gain. SIT is not some magic secret to getting the body of a fitness influencer; it’s just a nice, intense workout that will benefit your running.