HIIT Workouts: What They Are & Why They Work

Growing in popularity over the past year, HIIT (High-intensity interval training) workouts are all the rage. But what are they and why are they so popular? Exercise science professor Jessica Matthews gives us the lowdown.

April 8, 2014

It’s no secret: We all want better workout results in less time. The good news? As luck might have it, studies shows that there appears to be a perfect solution. Enter high-intensity interval training. Commonly referred to as HIIT, the concept behind these high-energy, time-efficient routines is not entirely new, yet in the last few years these types of workouts and class formats have grown tremendously in popularity given the desire by many to maximize workout results with as little time investment as possible. While HIIT-style workouts can come in many different forms research shows that this approach to exercise offers a plethora of health and fitness benefits for the time-crunched exercisers, from enhanced aerobic capacity to improved body composition.

More: 10 Interval Training Workouts That Will Melt Fat


If you’re new to HIIT-style workouts, it’s important to note that while they are intense in nature they can be scaled to accommodate any fitness level. Also keep in mind that high-intensity exercise doesn’t always have to mean high-impact. Joint-friendly alternatives can still certainly get your heart rate up in the event that high-impact moves like box jumps and burpees don’t best serve your body.

So if you’re in the market for an approach to exercise to boost your metabolism, maximize your fitness and elicit even better results all in less time get ready to HIIT it!

Ready to HIIT It?

Up the intensity of your next sweat session by performing each of the following exercises for 30 seconds using a weight that is appropriate for you (when applicable). After performing the move, actively recover for 15 seconds or less as you transition to the next exercise.

Don’t want to keep an eye on the clock? Try using this interval training device to keep your HIIT session on track. And if you have more than 6 minutes to spare and really want to take your fitness to the next level -- aim to complete the sequence two or three times for a fully supercharged workout you can do in under than 30 minutes.

Equipment you’ll need: Mat, BOSU ball (seen here), kettlebell, pair of dumbbells, and a stability ball

Dumbbell Thruster
Stand with feet hip-width apart holding a pair of dumbbells just above shoulders, palms facing in. Engage core, hinge at hips, and bend knees to a squat. Straighten legs, simultaneously extending arms overhead, keeping elbows pointed to 1 o’clock and 11 o’clock.
Reverse the movement to return to starting position.

BOSU Toe Taps
Begin in a high-plank position, with hands on each side of the BOSU (dome side down). Keep the core engaged, spine extended and weight evenly distributed so the chest is over top of the BOSU. Step the right foot to the outside of the right hand, being sure to keep the hips and shoulders squared to floor. Step back to high-plank position and switch sides, tapping the toes of the left foot to the outside of left hand. Continue alternating sides as quickly as possible while maintaining proper form and alignment.

More: Can You Get Fit in Just 3 Minutes?

Alternating Single-Arm Kettlebell Swing
Stand with feet hip-width apart, grasping the handle of a kettlebell in right hand using an overhand grip. Hinge at hips as you draw the kettlebell back between legs. Thrust hips forward, generating power from lower body to raise the kettlebell to shoulder height. Once at shoulder height, release the kettlebell momentarily mid-air to switch hands so the kettlebell is now in left hand. Continue, alternating hands.

Renegade Rows
Place a set of dumbbells on the floor and set yourself up in pushup position with feet hip-width apart and hands holding dumbbells. Keeping core engaged and hips and shoulders squared to the ground, perform a single-arm row with right hand: Pull right dumbbell to waist, pointing elbow directly to the ceiling. Lower weight back to the floor and repeat on the left side. Continue alternating arms.

Track Starters
Begin in a low lunge position with right leg back, left knee bent 90 degrees, and hands on either side of left foot. With the abs engaged, exhale and jump straight up, driving right knee and left arm forward, swinging right arm back, and keeping both elbows bent and close to sides. For a low-impact option skip the hop and instead rise up onto the toes. Return back to starting position and quickly jump switch the feet to repeat on the opposite side. Continue alternating sides.

High/Low Boat
Sit on mat with knees bent and feet flat on the floor. Pick up both feet up, keeping the knees bent 90 degrees as you come to high boat. Recline the torso back slightly as you keep the core engaged and the spine long. As you inhale, lower back with control to low boat, extending the legs out in front of you, hovering the arms, legs and torso close to the floor. As you exhale, rise back up to high boat.

More: Top 5 Strength Training Myths

From a forearm plank, press right palm into the mat and then left palm, coming to a high plank position. Upon exhale, release the right elbow and forearm back down to the mat and repeat on the left side, returning to a forearm plank position. Continue alternating sides each reps keeping hips and shoulders squared to the mat.

Unstable Mountain Climbers
Anchor a stability ball against a wall or sturdy park bench and come to a full plank position with hands on the ball and toes on the ground. Maintaining alignment, drive right knee into chest. Step the right foot back, switch sides and draw left knee into the chest. Alternate knees to chest as quickly as possible to up the intensity and increase the stability challenge.