Exercise & SportsHigh intensity interval training has many benefits

10 Scientifically Proven Benefits of High Intensity Interval Training (HIIT)

Serious athletes have long recognized the benefits of high-intensity interval training and science is now starting to confirm the benefits as well.

The idea behind high-intensity interval training (known as HIIT for short) is simple: less time needed to make big changes. But HIIT’s perks go beyond its time-saving benefits and science has the studies to prove it.

If you aren’t already on board with HIIT, our in-depth look at what it is and the benefits it offers may have you trying it the first chance you get.


What Is High-Intensity Interval Training (HIIT)?

HIIT involves short bursts of high-intensity exercise interspersed with low-intensity periods devoted to recovery.

For example, a HIIT workout with a stationary bike may consist of 30 seconds of cycling as hard as you can on the highest resistance followed by 30 seconds or a minute of slow, easy cycling at low resistance to complete one “round”.

It is a highly efficient method for gaining results quickly (workouts are usually only 10 to 30 minutes long). Despite the short duration of HIIT workouts, they may produce health benefits that rival twice the amount of moderate-intensity exercise (more on that below).

Read on for all the latest research on the scientific benefits of high-intensity interval training.


1. You Will Continue to Burn Calories Even After You Finish Your Workout

HIIT burns more calories while working out — and after — than continuous aerobic training thanks to the increased caloric expenditure that results from the higher intensity. More calories burned equals more results.

Better yet, the body continues to burn calories for up to two hours after a HIIT workout due to a process called exercise post-oxygen consumption (EPOC).

EPOC refers to the oxygen needed by the body to restore itself back to its pre-workout state. During exercise, the body uses oxygen to produce fuel (adenosine triphosphate or ATP) for your muscles. It can also rely on stored energy sources that do not need extra oxygen.

Since HIIT workouts tend to utilize the latter, they also require a higher amount of oxygen post-workout, meaning these short, intense bursts of exercise lead to an afterburn effect.

Oxygen and calorie burn go hand in hand following a workout and the metabolism stays revved up. Eating sufficient, high-quality protein following a workout also helps encourage a healthy metabolism.


2. You Are More Likely to Stick With It

Beyond being effective, high-intensity interval training is also enjoyable! And science backs this up.

People enjoy high-intensity interval training more than continuous moderate-intensity or vigorous-intensity exercise according to this study. Enjoying a workout increases your likelihood of sticking to it.


3. HIIT Workouts Can Improve Your Endurance

Next time you are on a run, crank up the intensity for a minute here and there. Just three minutes of high-intensity training can improve your endurance and boost your overall health. This boost in endurance will carry over to your life and training, leading to all around benefits.

HIIT running up stairs


4. HIIT Workouts Can Increase Your VO2 Max

You may not think a single workout session can have any noteworthy effect, but if you are doing HIIT, one study says it can. A group of individuals with type 2 diabetes was instructed to complete a moderate intensity walk or a walk interspersed with intervals five days a week for an hour for four months.

The results were surprising: VO2 max increased in the walking group that incorporated intervals, but not in the continuous walking group. The interval group also saw a decrease in fat and improved glycemic control.


5. HIIT is Extremely Efficient

HIIT’s efficiency is well known, but now there is scientific proof to back it up. You can burn more calories in less time according to a study in the Journal of Psychology.

The study compared sedentary men who completed between 40 and 60 minutes of cycling five times per week at 65 percent of their max with men who did spring intervals during just 12 minute sessions three times per week. Participants in both the continuous intensity and high-intensity interval training groups saw similar results and also showed increased insulin sensitivity and reduced aortic stiffness.


6. HIIT Is Versatile

Think HIIT is just sprinting, sprinting, and more sprinting? Fortunately, high-intensity interval training can take many forms. Various activities including jumping rope, sprinting, biking, body weight exercises, or plyometrics can all successfully incorporate interval training. So find your favorite way to move and have some fun!


7. HIIT Is Heart-Healthy

When it comes to flexibility, touching your toes isn’t the only thing that matters. Your arteries and veins need to be flexible as well, and HIIT can help improve the flexibility and elasticity of veins and arteries better than continuous aerobic exercise. Since high-intensity interval training increases pressure demand on blood vessels, it acts as a workout for them too!

Research also indicates that high-intensity interval training can have a positive impact on blood pressure and heart rate in overweight and obese individuals.


8. HIIT Can Help You Lose Fat

Core workout

Studies have shown that HIIT workouts can help you lose fat, even the particularly dangerous visceral fat (a type of fat that surrounds the inner organs).

One study followed individuals performing HIIT workouts three times a week for 20 minutes per session. In 12 weeks — and without any dietary changes — participants lost 4.4 pounds.

Even more important was the striking reduction — 17 percent! — in visceral fat.

Several other studies confirm that HIIT workouts can reduce body fat despite the limited time commitment invovled.


9. HIIT Promotes Muscle Growth

Along with fat loss, HIIT may also help promote the growth of lean muscle mass in certain individuals.

This muscle gain is most often seen in the muscles that are used the most, typically the legs and trunk.

It’s worth noting that individuals who were less active in the first place are more likely to notice an increase in muscle mass.


10. Blood Sugar Can Be Reduced by HIIT

Studies also suggest that HIIT can have a positive impact on blood sugar levels and insulin resistance, even more so than traditional continuous exercise.

These findings may suggest that HIIT workouts are especially beneficial for individuals at risk of type 2 diabetes.


Final Thoughts

High-intensity interval training is scientifically proven to offer a variety of benefits. It may even produce many of the same health benefits as other types of exercise in less time.

If you are short on time and haven’t tried high-intensity interval training yet, now might be a great time to start!

Have you heard of HIIT? Do you already incorporate HIIT into your exercise routine? What are some of your favorite HITT workouts? Let us know in the comments – we always enjoy your feedback.