High-intensity interval training, or HIIT, is a type of exercise that can quickly push you to your limits. There’s been a lot of research lately on just how effective HIIT can be, and the results are pretty awesome.

Usually, HIIT is thought of as a set of exercises that push you to 80–90% of your max heart rate, and have you sucking air after 5 minutes. That’s not a bad thing though, as we’re finding out!

Research on HIIT has been focused on…literally everything. From metabolic diseases, obesity, even elite athletes, HIIT has been looked at for its possible health benefits for a LONG time. So let’s dive in and take a look at some of the research (I promise to make it interesting).

2015 HIIT and Fat Tissue Study

The first study really hits home as to how effective high-intensity interval training can be. Just last year, Tomas Tong performed a fairly simple study on the effects of HIIT on abdominal fat loss in untrained women. One group performed a simple HIIT program, 4 bouts of 4-minute runs at 85–95% of their max heart rate (with 3 minute breaks in between), 4 days per week. Another group ran for 33 minutes continuously at 60–70% of their max heart rate. The third group was a control that did not exercise. The protocol lasted for 5 weeks.

What do you think happened? Obviously, this post is about HIIT, so it must have been effective. Turns out, it really was! Both exercise groups lost a significant amount of abdominal fat. However, the HIIT group lost more subcutaneous fat AND visceral fat over the five-week period. This is a big deal, as visceral fat has been linked to metabolic issues, and cardiovascular disease.

Just let Harvard put it simply:

“Scientists are also learning that visceral fat pumps out immune system chemicals called cytokines — for example, tumor necrosis factor and interleukin-6 — that can increase the risk of cardiovascular disease. These and other biochemicals are thought to have deleterious effects on cells’ sensitivity to insulin, blood pressure, and blood clotting.”

2013 HIIT Study in Distance Runners

This study looked at a more specific approach to HIIT, by comparing flat-ground intervals vs. uphill intervals in distance runners. Each group did bouts of 30 seconds either uphill or flat (on a treadmill). Their bouts were based on various physiological factors, but simply put, they were pushed to their limits.

After 12 weeks of this, researchers found that runners in both groups improved in their running times at a high rate of oxygen uptake. They also found that the flat-ground runners significantly improved their time-to-exhaustion, obviously a big deal for distance runners.

I used this study to show that HIIT isn’t just for a specific group of people. It can be beneficial for almost anyone, provided it’s done safely! Now, onto the last study.

2016 HIIT Study on Enjoyment

Now this study is pretty awesome, because they looked not only at physiological factors with HIIT training, but also the enjoyment factor for people doing HIIT vs continuous running.

The study was five weeks long, and looked at overweight young women (18–30). One group did 20 minutes of cycling with 8 second bouts of 100% effort, with 12 second breaks. The other group cycled continuously for 40 minutes at approximately 60–80% of their max heart rate. What researchers found was that in every week of the study, HIIT participants enjoyed their activity more than moderate-intensity participants.

This is probably the most important piece you can take out of this post. The benefits of exercise mean nothing if you don’t enjoy it! Achieving lifelong fitness and health would be unsustainable if you hated doing it every day. So why not try something that could actually be fun!

While three studies is far from the extent of info we have on HIIT, hopefully this is enough to get you thinking about trying HIIT someday. It’s a very intense workout, but much shorter than just running on a treadmill. And much less boring. Fitness should be fun!

Do you want to learn more about HIIT? I will be writing up a piece on specific workouts you can do to get started in high-intensity interval training, available to all my email subscribers. If you want some awesome tips to get started with HIIT, sign up here FOR FREE! I literally just need a name and email to send this awesome information to.

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