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Some fitness fads come and go (we see you, Shake Weight), but others, like yoga and Pilates, aren’t going away any time soon. Another trend that’s definitely here to stay? HIIT.

HIIT, or high-intensity interval training, involves short bouts of extreme effort alternated with periods of rest.

“HIIT workouts are quick and dirty, never lasting more than 30 minutes including a warmup and short cooldown,” explains Gina Harney, certified personal trainer and creator of Fitnessista.com.

“You’re working as hard as possible for a short amount of time and then reaping the rewards throughout the day,” she says.

While there’s no such thing as a fitness miracle, HIIT workouts come pretty darn close. In fact, research suggests HIIT might just be a magic bullet for fat loss.

A 2019 study found that participants doing a HIIT program had 29 percent more absolute fat loss than people doing moderate-intensity continuous training.Viana RB, et al. (2019). Is interval training the magic bullet for fat loss? A systematic review and meta-analysis comparing moderate-intensity continuous training with high-intensity interval training (HIIT). DOI: 10.1136/bjsports-2018-099928

Research shows HIIT can also supercharge your cardiovascular fitnessWeston KS, et al. (2014). High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: A systematic review and meta-analysis. DOI: 10.1136/bjsports-2013-092576 and decrease your blood pressure at night.Way KL, et al. (2019). The effect of high Intensity interval training versus moderate intensity continuous training on arterial stiffness and 24h blood pressure responses: A systematic review and meta-analysis. DOI: 10.1016/j.jsams.2018.09.228

Plus, a 2017 study showed that HIIT is great for improving overall body composition, muscle strength, mobility, and balance in healthy older adults.Garcia-Pinillos F, et al. (2017). Effects of 12-week concurrent high-intensity interval strength and endurance training program on physical performance in healthy older people. DOI: 10.1519/JSC.0000000000001895

Bottom line: HIIT is quick and effective. And for anyone who’s short on time and wants to see results stat, it’s the perfect way to train.

Get started with this exclusive upper-body workout for women from Harney’s book HIIT It!

In less than 30 minutes, these highly effective circuits will target and strengthen every muscle above your waist. All you need is a set of medium-weight dumbbells and your body weight.

To warm up, do 5 minutes of moderate cardio, like jogging, jumping rope, or cycling. This will get your heart rate up and your muscles nice and warm.

Complete 3 rounds of circuit 1, and then rest for 30 seconds to 1 minute. Boost your heart rate again by running or walking a quarter of a mile.

1. Overhead press

Reps: 12

Hold a set of dumbbells and bend your elbows to 90 degrees, with upper arms parallel to the floor and dumbbells at about head height.

As you exhale, press the dumbbells overhead without clanking them together. Return to starting position and keep resistance by preventing elbows from drooping below shoulder height.

2. Triceps kickback

Reps: 12

Hold a dumbbell in each hand. Hinge forward at hips, keeping core tight and back flat. Bending elbows, glue upper arms to your sides.

On an exhale, straighten arms as much as possible. Inhale and bend elbows to return to starting position. Be sure to maintain neutral spine and neck position.

3. Chest press

Reps: 12

Lie faceup on a mat, holding a dumbbell in each hand. Bring elbows out in line with shoulders to create a 90-degree angle.

Press the dumbbells up without clanking them together, focusing on engaging chest muscles. Lower the dumbbells back to starting position.

Complete 3 rounds of circuit 2, followed by a cool-down stretch, and you’re done! That wasn’t so bad, was it?

1. Side plank with lateral raise

Reps: 12 per side

Start in a side plank, either full or modified by keeping your bottom knee on the floor. Hold a light dumbbell in your top hand. Bring dumbbell in front of the center of your core.

Keeping arm slightly bent, lift dumbbell to shoulder height. Return to starting position.

For more of a challenge, you can lift your top leg and touch it to the dumbbell after each rep.

2. Push-up

Reps: 15

Start in a plank position with hands planted directly under shoulders, slightly wider than shoulder width. Press toes into the floor to stabilize the bottom half of your body.

Keep your spine straight, hips level, and neck in line with spine instead of dropping it forward. With palms pressing into the floor, lower until your chest almost grazes the floor. Exhale as you press back up.

3. Triceps dip

Reps: 15

You can do this exercise with your hands on a bench and feet on the floor, or you can do it on the floor.

Point fingertips toward toes and bend elbows, making sure to keep hips lifted. Straighten arms by engaging triceps.

For an added challenge, straighten your legs, balance on only one leg, or place a weight plate on your lap.

Warm up with 5 minutes of moderate cardio. Complete 3 rounds of circuit 1, and then rest for 30 seconds to 1 minute. Run or walk a quarter of a mile, and then complete 3 rounds of circuit 2. Be sure to do a cool-down stretch.