High-intensity interval training, or HIIT, checks two of the most important boxes when it comes to exercise programming: high effectiveness in a short amount of time. HIIT workouts are very challenging and feature short bursts (or intervals) of very high-intensity exercise followed by brief active recovery periods.
For example, a 30-minute HIIT workout in an indoor cycling class might involve alternating between 30 seconds of maximal-effort sprints and 90 seconds of less-intense pedaling (i.e., active recovery) for 10 rounds, plus a five-minute warm-up and a five-minute cool-down.
What to Know About HIIT
You can make HIIT work for you by learning about the benefits, potential pitfalls and engaging variations that this workout program has to offer.
— Benefits of HIIT.
— Strength training options.
— Potential pitfalls.
— Sample HIIT workouts.
Benefits of HIIT
There are countless variations on the format, as the duration and intensity of both the high-intensity and recovery periods can be modified depending on a person’s fitness level and goals. Even better, the benefits are impressive: high calorie burn, lasting increase in metabolism, enhanced weight and fat loss and increased muscle strength and size.
HIIT can also drive important health benefits, including better oxygen consumption (a key marker of cardiorespiratory health), reduced blood sugar and improved heart rate and blood pressure.
Unlike some other workout programs, one benefit of HIIT is that it’s highly accessible, meaning that it can be accomplished without an expensive gym membership or even any equipment at all.
Almost any form of movement can be the centerpiece of a HIIT workout, including walking, running, biking and jumping rope. Body-weight strength training (like squats, lunges, push-ups and pull-ups) are also great options for circuit training-style HIIT workouts.
HIIT workouts are not for everyone, but they may be appropriate for more people than you’d think, including people of any age. Remember, the intensity of exercise should be relative to your personal fitness level, so “going all out” means something different to each of us. The benefits of HIIT rely on a willingness and ability to push yourself, whatever that means to you.
Strength Training Options
You can incorporate HIIT principles into your strength-training regimen in two unique ways. One method is called high-intensity resistance training, which involves using heavier weights for fewer repetitions, followed by a brief — roughly 20- second — rest period.
The second method is called high-intensity cardioresistance and involves alternating between strength exercises and bursts of cardio or calisthenics exercises. For example, perform a set of squats followed by 60 seconds of high-knee marching, then dumbbell rows followed by 60 seconds of jumping jacks. The idea behind both techniques is that you’re alternating between high- and low-intensity exercise or rest.
[Read: HIIT vs. Cardio for Weight Loss.]
There is one major caveat when it comes to HIIT. Performing it too often can potentially backfire, leaving you prone to fatigue and possible injury, particularly in the joints. High-intensity exercise is a considerable stressor, and too much of any stressor is not ideal.
HIIT workouts cause a short-term spike in cortisol (a hormone that is part of the “fight or flight” response), which makes the body grow stronger. But maintaining high levels of cortisol over the long haul, which can happen if you don’t adequately recover between workouts, can actually lead to weight gain and digestive issues.
Other potential downsides of too much HIIT include depleted glycogen levels, which can leave you feeling slower and weaker during workouts and slower to recover between bouts of exercise. Also, performing a HIIT workout too close to bedtime can cause sleep disruptions.
Reasons to avoid HIIT
There are also certain situations when HIIT may not be the best choice. For example, if you’re feeling very stressed on a particular day, it might be best to put your HIIT workout off until you feel better. In the meantime, stick with more moderate forms of exercise. Pushing yourself to maximal effort places additional stress on the body and mind that may be counterproductive.
If you have joint issues or chronic pain, you can still perform low-impact HIIT workouts. For example, if you have pain in your knees and walking is your preferred form of exercise, jogging or running may be too high-impact to be included in a HIIT program. In that case, try a HIIT cycling workout, which is an effective low-impact option.
Sample HIIT Workouts
If you’re new to HIIT, here are a few examples of what a beginner-level HIIT session might look like:
— Jogging/running HIIT: After warming up for a few minutes, alternate one to two minutes of jogging with 15 seconds of all-out sprinting for a total workout lasting 10 to 20 minutes.
— Strength training/circuit training HIIT: Warm up by walking or performing other low-intensity cardio for a few minutes. Then, perform 10 repetitions of three different exercises, like lunges, push-ups and curl-ups, followed by one minute of high-intensity cardio, like high-knee marching or getting on the elliptical trainer. Alternate the strength training and cardio for the desired duration of your workout.
— Walking HIIT: Warm up by walking for a few minutes at a normal pace, then alternate one minute of fast-paced walking with one-minute of slower walking for the desired duration of your workout. Another option is to measure distance rather than time. For example, if you are on a quarter-mile track, alternate walking a half lap at a fast pace with a half lap at a slower pace.
As with all things, appropriate dosing is key. Just because HIIT is an effective and efficient form of exercise doesn’t mean it should be your only form. It is best to perform HIIT workouts on nonconsecutive days and to do less intense types of physical activity on other days. It’s also a good idea to take occasional breaks from HIIT for a few weeks at a time, during which you can shift your focus to other forms of exercise like strength training or outdoor activities.
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