If losing weight or getting in shape tops your fitness to-do list, there's a good chance you know a thing or two about high-intensity interval training, aka HIIT. Besides the obvious benefits of scorching calories and increasing your fitness levels, HIIT also allows you to get the most work done in the least amount of time.
In other words, when done right, HIIT gets you fit, fast.
What Is HIIT, Exactly?
HIIT gets used a lot in training conversations. And while some of the information you may hear is spot on, other tidbits of wisdom may not be so accurate. So, let's clear up a few things before you do a billion burpees and hurt yourself.
In general, HIIT is a type of workout that pairs high-intensity exercise intervals with low- to moderate-intensity active recovery phases. According to the American College of Sports Medicine, each interval can range from a few seconds to a few minutes, and the intensity of the intervals can vary based on your current fitness level. The type of exercise you use to do a HIIT workout is entirely up to you.
For example, if you want to do a cardio HIIT workout, Bonnie Micheli and Tracy Roemer, co-founders of Shred415, say you can use equipment, like a treadmill or elliptical machine, or simply head outside. For a 30-minute session, aim to perform 30 seconds of fast exercise followed by a one-minute slower-paced active recovery interval. "This is a great way to burn calories in a short amount of time," Micheli says.
For a full-body HIIT workout that focuses on strength, choose several body-weight exercises such as squats, push-ups, lunges, mountain climbers and planks. Try performing them in a Tabata set-up: Perform each exercise at your maximum effort for 20 seconds, followed by a 10-second rest period. Do the circuit twice.
Benefits of HIIT
1. HIIT Improves Your Cardiovascular Fitness
HIIT helps boost your cardio-respiratory health in a shorter period of time. An April 2015 systematic review and meta-analysis in Sports Medicine examined the research on HIIT and VO2 max and found that gains in VO2 max (your maximal oxygen uptake, a measure of your cardiovascular fitness) were greater following HIIT when compared with endurance training. These VO2 max gains can help boost your performance in activities like running, cycling, rowing and cross-country skiing.
2. HIIT May Improve Your Overall Health
With those cardio gains come other positive health changes, all thanks to HIIT. In a March 2012 study published in The Journal of Physiology, researchers found that HIIT can serve as an effective alternative to traditional endurance-based training. More specifically, they discovered a link between HIIT and improved health outcomes and cardio fitness in a range of populations, including those with coronary artery disease, congestive heart failure and middle-aged adults with metabolic syndrome.
3. HIIT Helps You Customize Your Workouts
Many beginners are hesitant to do HIIT because they believe it's only for hard-core gym junkies or athletes. The good news is, you can customize your intervals by varying the time and intensity to fit your fitness needs. "The goal is to get your heart pumping," Micheli says. "So you can go at your own pace, including a slow walk to a fast walk." To determine if an interval is intense enough for you, monitor your breathing. You should be breathing heavily enough that it's difficult to speak more than a few words at a time.
Read more: What's a Good Exercise Heart Rate?
4. HIIT Allows You to Exercise Anywhere, Anytime
One of the many benefits of HIIT is that you can perform the workouts anywhere: at the gym, at home or on the road. Since you're not required to use any specific cardio or weight equipment, you can sneak in a sweat-dripping session morning, noon or night — no excuses.
5. HIIT Helps Preserve Muscle Mass During Weight Loss
Weight loss and maximum muscle mass can sometimes be in conflict with each other. That's because when the number on the scale decreases, especially quickly, it's not just fat that you're losing; you may also be sacrificing hard-earned muscle. However, HIIT might help: An April 2012 study in the Journal of Obesity found this type of training can reduce body fat, improve aerobic fitness and preserve lean muscle mass. (And the more lean muscle mass you maintain or gain, the more calories your body will burn, even at rest, supporting your long-term weight-loss goals.)
6. HIIT Keeps Your Metabolism Elevated After Exercise
The puddles of sweat make it obvious that HIIT cranks up your metabolism during a workout. But did you know that this form of exercise also helps you burn calories for several hours afterward? You read that right.
When you finish exercising, your body still needs extra oxygen and your metabolism stays elevated thanks to something called excess post-exercise oxygen consumption or EPOC. Essentially, the higher the intensity, the longer it will take metabolism to return to its normal, resting level, according to the American Council on Exercise. It's during this recovery process that you continue to burn extra calories.
Read more: How to Do a HIIT Workout at Home
Tips for Doing More HIIT Workouts
HIIT is not an easy method of exercise. Use these tips to incorporate high-intensity intervals into your workouts safely and effectively.
- Make it a full-body workout. When designing a HIIT routine that focuses on strength, Andrew Mariani, trainer at Fhitting Room, says to always include upper- and lower-body movements to ensure you hit all of the major muscle groups.
- Add explosive moves. Mariani also says to incorporate both explosive moves during intervals and slower-tempo intervals in your workout. This is a great tip for more advanced fitness fans who might want to add in some plyometric exercises such as box jumps, squat jumps and plyometric push-ups for the work phase of the intervals.
- Avoid complete rest. HIIT is all about getting in and getting out. This means that your rest periods need to be active recovery, not "sit on the weight bench and check Instagram" recovery. To fill the "rest period," Mariani says to drop to the floor for 15 seconds of static core work (think: planks).
- Think of HIIT as one tool. With all of the fantastic benefits that accompany a HIIT session, you might be wondering if you can ditch the rest of your routines and just stick with HIIT. The short answer is "no." Because the intensity is high, you don't want to perform these types of workouts too often. In general, incorporating two to three non-consecutive days of HIIT workouts into your overall fitness routine will allow you enough recovery time, while still delivering excellent results.
Read more: 5 Ways to Supercharge Your HIIT Routine
- The Journal of Physiology: "Physiological Adaptations to Low-Volume High-Intensity Interval Training in Health and Disease"
- The American College of Sports Medicine: "Interval-Based Exercise: So Many Names, So Many Possibilities"
- The Journal of Sports Medicine: "Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials"
- The Mayo Clinic: "Metabolism and Weight Loss: How You Burn Calories"
- The Journal of Obesity: "The Effect of High-Intensity Intermittent Exercise on Body Composition of Overweight Young Male"
- American Council on Exercise: "7 Things to Know About Excess Post-exercise Oxygen Consumption (EPOC)"