High-Intensity Interval Training (HIIT): What It Is and Why It’s Good for Your Health

Have you heard people talking about high-intensity interval training (HIIT) and wondered what it’s about? Sometimes called speed interval training, HIIT is a form of anaerobic exercise involving alternating between intense bursts of exercise, where you go as hard as you can, and fixed periods of less intense activity or rest. It’s a science-backed way to burn fat and calories, boost your metabolism, build muscle and more — and it only takes about 15 minutes.  

Health Benefits of HIIT

The short, intense periods of activity at the heart of HIIT are a type of anaerobic exercise. During anaerobic exercise, your body breaks down glucose for exercise without using oxygen (as opposed to aerobic exercise, which requires oxygen). 

This type of fast-paced, high-intensity exercise offers a number of health benefits. Here are some of the primary ones.  

It’s Quick

Because you’re giving 100% during the active intervals of HIIT, you don’t have to spend much time to get an effective workout. 

It Burns Fat 

Many studies have shown that HIIT can reduce body fat and waist circumference, particularly for people with obesity.  

It Builds Muscle 

Research suggests HIIT helps build lean muscle mass and increase strength. It may be particularly beneficial for helping people who aren’t already very active become more muscular. 

It Boosts Metabolism 

Because the activity done during this type of workout is so intense, your body actually continues to burn calories long after you’re done exercising. Science indicates HIIT can boost your metabolic rate for hours post-workout.  

It’s Good for Your Heart 

Doing HIIT regularly can help your heart work better, pumping blood more efficiently. It may also cause blood vessels to widen and become more flexible, which could lead to lower blood pressure.  

It Helps Regulate Blood Sugar 

For people with conditions such as type 2 diabetes that struggle with high blood sugar, HIIT may have a stabilizing effect. A systematic review and meta-analysis of 22 studies involving more than 1,000 people with diabetes found HIIT improved blood sugar levels and lipid metabolism (the breakdown of fat).  

It Can Be Done Anywhere  

One of the best things about HIIT is that it can be done anywhere and requires no equipment. You can even do this type of workout in your hotel room while traveling. 

HIIT How-To

You can take any kind of exercise and turn it into HIIT. One example of this type of exercise is running as fast as you can for one minute and then walking for two minutes, repeating this three-minute interval five times for a 15-minute workout. 

Another simple HIIT workout involves cycling for one minute as hard as you can (or 85%), then bringing it down to 25% or resting for 2 minutes for a total of 15 minutes. 

Or you could do squat jumps as quickly as possible for 30 to 90 seconds, then stand or walk for 30 to 90 seconds, repeating for 15-20 minutes. 

When first starting out with HIIT, it’s probably best to choose an activity that you’re already comfortable doing at a lower intensity. For example, don’t do a sprint workout if you’ve never done any running or jogging. The important thing is to alternate between going all out (between 85% and 100%) and taking it easy (no more than 25%) or resting — and to keep repeating the pattern for about 15 or 20 minutes.  

Big Picture Takeaways 

1. One of the greatest advantages of HIIT is its time efficiency – it typically takes only 15-20 minutes to complete. You do not have to spend hours exercising to get in better shape. Incorporating HIIT into your fitness routine allows you to get an efficient, high-calorie-burning workout.
2. You can perform HIIT almost anywhere, with no gym membership or special equipment required.
3. You can add HIIT workouts to any weekly or monthly exercise routine and apply them to many forms of exercise. Most of us can benefit from making HIIT part of a well-rounded fitness plan, along with aerobic exercise, weight training, yoga, Pilates, and other forms of movement that work different parts of the body.
4. HIIT is a form of anaerobic exercise. While traditional aerobic exercise has obvious benefits, anaerobic exercise is often overlooked. Comparing sprinters and marathon runners highlights the different adaptations associated with these two approaches. In fact, a recent study from Denmark found that HIIT may increase certain muscle proteins involved in energy metabolism and muscle contraction, which helps explain how this quick but effective type of training can impact muscles and boost a person’s metabolic rate long after a workout.

Editor’s Note: This article was originally published on January 16, 2014, and was updated on February 9, 2026