Is your ab workout [1] beginning to feel a little stale? If so, give it a break and show your core some TLC with this strengthening workout [2]. During this workout you'll be targeting and strengthening all the muscles that make up your core: the tranverse abdominis (your deepest core muscle), obliques, and rectus abdominis. Are you ready to put in work? Let's get started!

The workout:

• This workout is broken up into three circuits. You'll complete every exercise in the circuit and then take 90 seconds of rest before advancing to the next circuit.
• Once you've completed all three circuits, take one to two minutes of rest and repeat for one more round.
• If you're short on time, pick one circuit and repeat it three times.

Related:

I'm a Trainer, and This Is the Ab Workout I Do For a 6-Pack [3]

Circuit 1, Exercise 1: High Knees

• Run in place while lifting your knees high to the level of your waist. Engage your abs as the knee comes up.
• Pump your arms to warm up your upper body.
• Complete 30 reps.

Circuit 1, Exercise 2: Plank With Knee Tap

• Start resting on all fours.
• With your palms flat, raise up off your knees onto your toes. Keep your hands directly below your shoulders.
• Contract your abs to keep yourself up and prevent your bottom from sticking up. Remember to keep your belly button pulled in.
• With your head and spine in line, keep your back flat — don't let it curve. Picture your body as a long, straight board.
• With control, slowly tap your left knee to the ground without moving your hips. Lift your left knee back up, returning to the starting position. Repeat the same movement with the right leg. This counts as one rep.
• Complete 10 reps.

Circuit 1, Exercise 3: Bicycle Crunches

• Lie flat on the floor with your lower back pressed to the ground (pull your abs down to also target your deep abs). Interlace your fingers and put your hands behind your head.
• Bring your knees in toward your chest and lift your shoulder blades off the ground.
• Straighten your right leg out to about a 45-degree angle to the ground while turning your upper body to the left, bringing your right elbow toward the left knee. Make sure your rib cage is moving and not just your elbows.
• Now switch sides and do the same motion on the other side to complete one rep (and to create the "pedaling" motion).
• Complete 30 reps.

Circuit 1, Exercise 4: Scissor Kicks

• Lying on your back, lift your legs two to three inches off of the ground. Place your hands on the floor beside you or underneath your lower back for extra support.
• Cross your right ankle over your left ankle, then cross your left ankle over your right ankle.
• This counts as one rep.
• Complete 10 reps.

Circuit 2, Exercise 1: Tuck Jump

• Start in a squat position with your feet hip-width apart and arms down, making sure your knees are in line with your feet.
• Swing your arms up and jump into the air, bringing your knees up toward your chest so they go past your hips.
• Land, with your knees slightly bent, onto the balls of your feet for a quiet landing.
• Without pausing for the next rep, repeat the motion.
• Complete 15 reps.

Circuit 2, Exercise 2: Plank With Shoulder Tap

• Begin in a plank variation with your feet slightly wider than your hips for added stability.
• Keeping your torso stable, bring your right hand to your left shoulder, then return your right hand back to the mat.
• Bring your left hand to your right shoulder and return it to the mat. This counts as one rep.
• Complete 10 reps.

Circuit 2, Exercise 3: Reverse Crunch

• Lying on your back, lift your legs in the air with your knees bent. Place your hands on the floor beside you.
• Without momentum, use your lower abs to slowly curl the hips off the floor and into your chest. Slowly lower them back to the starting position.
• This completes one rep.
• Complete 15 reps.

Circuit 2, Exercise 4: Bird Dog

• Get on all fours, with your knees under your hips and your hands under your shoulders. Remember to keep abs engaged and keep your back flat.
• Reach out with your right hand and extend your left leg out behind you.
• Round your back and head to connect your right elbow with your left leg under your body. This completes one rep.
• Complete 10 reps on each side.

Circuit 3, Exercise 1: Mountain Climbers

• Start in a traditional plank — shoulders over hands and weight in your toes.
• With your core engaged, bring your right knee forward under your chest, with the toes just off the ground. Return to your basic plank. Switch legs, bringing the left knee forward.
• Keep switching legs and begin to pick up the pace until it feels a little like running in place in a plank position.
• Complete 30 reps.

Circuit 3, Exercise 2: Double Leg Lifts

• Lay flat on the ground with your legs extended straight up toward the ceiling. Place your hands underneath the back of your head. For added stability, Austin recommends laying your arms out to your side, allowing the palms to grip the floor much like you would in a push-up position.
• Pressing your lower back into the ground, slowly lower both legs down toward the floor, then slowly raise them back up. If this is too difficult, lower them as much as you can, or lower one leg at a time.
• Complete 10 reps.

Circuit 3, Exercise 3: Forearm Plank Hip Dips

• From an elbow plank, slowly rotate the spine to lower your left hip to just above the floor (about one to two inches from the ground). Come back to elbow plank.
• Now lower the right hip toward the floor. This counts as one rep.
• Complete 10 reps.

Circuit 3, Exercise 4: Seated Russian Twist

• Sit on the ground with your knees bent and your heels about a foot from your bum.
• Lean slightly back without rounding your spine at all. It is really important and difficult to keep your back straight, but don't let it curve. If you can do this, try lifting your heels to increase the difficulty of the move.
• Place your arms straight out in front of you with your palms touching. Your hands should be level with the bottom of your rib cage.
• Pull your navel to your spine, and twist slowly to the left. The movement is not large and comes from the ribs rotating, not from your arms swinging. Inhale through center, and rotate to the right. This completes one rep.
• Complete 10 reps.