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If your goal is to strengthen and tone your midsection, you likely focus on exercises like crunches and situps that work the superficial core muscles like the rectus abdominis (or the “six-pack abs”) and the external obliques.

But the most important core muscles are actually those you can’t see with the naked eye. The deep core muscles are responsible for balance and posture, reducing back pain and maintaining core strength.

Here’s what you need to know about your deep core muscles — and exercises to target and stengthen them.

What are the deep core muscles?

Deep core exercises work by targeting the muscles that provide support and stability to your spine and pelvis. These muscles include:

• Transversus abdominis: the innermost layer of the abdominals

• Multifidus: the muscle that runs along the spine

• Pelvic floor muscles: a group of muscles that help support the spine and play a role in bladder control

• Diaphragm: a muscle that sits below the lungs and helps you breathe in and out

By strengthening these muscles, you are also helping to reduce the strain on your back. This can lead to improved posture, reduced discomfort and increased mobility.

Tips for working your deep core muscles

• Find them first: One mistake people make is relying too much on the superficial muscles, like the rectus abdominis, instead of engaging the deep core muscles. To locate the deep core muscles, “draw in” by pulling your belly button to your spine or pretending you’re zipping up into a pair of tight pants. You should feel those deep core muscles turn on.

• Breathe: It’s easy to hold your breathe when performing deep core exercises, after all, it takes a lot of focus! But the muscles need oxygen like the lungs do, and holding your breath can cut off that supply and devalue the exercises.

• Slow down: Working the deep core muscles isn’t about the number of repetitions you complete, but the quality of your movements. Take your time and perform the movements with control and precision. It is better to do fewer reps with proper form than to rush through them with poor form.

Modifications as you build core strength

Deep core exercises can be challenging, so modify as needed to build up that strength. Start with simpler versions of the exercises and gradually progress to more advanced variations. For example, if planks are too challenging, you can begin with a modified plank by resting on your knees instead of your toes. Using a resistance band around your thighs during exercises like bridges is another way to provide additional support and help activate those deep core muscles.

11 deep core exercises

Are you ready to work your deep core muscles? Here are some exercises to target those important muscles. Performing a few of these exercises is a great warm up before a walk, run or strength routine. Or string them all together for a deep core workout routine.Bird dog

Start on all fours with your shoulders over your wrists and hips stacked above the knees. Straighten your left arm out in front of you and your right leg out behind you, balancing on your opposite hand and knee. Hold for a few breaths. For an added challenge, bend your left elbow and your right knee in toward each other until they touch underneath your stomach. Switch sides and repeat using your right arm and left leg. Continue alternating, performing 10 reps on each side.

Bridge

Start lying on your back. Rest your arms straight down at your sides with your palms on the floor and bend your knees so that your ankles are under your knees. With your head resting on the floor, slowly raise your hips in the direction of the ceiling by curling up your low back, middle back and then upper back. Once you have a straight line from your neck to your knees, hold and take a deep breathe in. Then, exhale as you slowly roll down one vertebra at a time. Repeat 10 times.

Flutter kick

Lie on your back with your legs straight up toward the ceiling. Let your arms rest down at your sides. You can also place your hands under your butt for increased stabilization. Squeeze your core and lower both of your legs 6-12 inches to about a 45-degree angle. Lift one leg up as your lower the other to the floor. Switch legs. Continue to alternate, moving your legs in a flutter motion. Repeat for about 15 repetitions, making sure not to maintain a steady pace as you go.

Toe taps

Lie on your back with knees bent and feet flat on the ground. Take a deep breath in, then exhale as you draw your naval in toward your spine, and slowly bring both knees up to a table-top position. Draw your lower ribs down toward your hips and tighten your core as if you were wearing a corset. From here, lower the right leg down to tap the toe on the ground while maintaining the engagement of the core. There should be no movement above the hips, and the back should stay gently pressing into the ground. Exhale as you lower the leg down, and inhale to bring it back up. Repeat on the left leg. Continue alternating, performing 20 taps total.

Bicycle crunch

Lie on the floor with your legs straight out in front of you. Place your hands gently behind your head with elbows bent out toward the sides. Engaging your core, lift your legs and upper back off the floor. Then, keep your right leg straight as you bring your left knee toward your right elbow. Alternate sides, focusing on your obliques and rectus abdominis. Repeat for 10 repetitions to each side.

Mountain climbers

Begin in plank position, keeping your back straight, your hips low and your core engaged. Bring your right knee under your chest toward your right elbow. Return your right leg back to plank position; bring your left leg under your chest toward your left elbow. Repeat while alternating your legs, keeping a steady pace. Remember to breathe and concentrate on engaging your abs, glutes and hamstrings. Repeat for 10 repetitions to each side.

Plank

Come onto your hands and knees, opening the hands as wide as the shoulders and the knees as wide as the hips. Pull the abs in and step the feet back to come up into a plank position. Make sure the shoulders stay over the wrists and be mindful not to round or arch the back. Engage the core to keep your back flat. Hold for 10 seconds, rest, and repeat for a total of 3 times.

Hollow hold

Lying flat on your back, start with your arms and legs reaching straight up toward the ceiling. Exhale as you pull your naval in toward your spine and slowly lower the arms behind you and the legs in front of you. Only go as low as you can without allowing your low back to arch! Hold for 10 seconds, rest, and repeat for a total of 3 times.

Dead bug

Start lying on your back. Keep your shoulders and low back flat on the floor as you lift your arms straight toward the sky, above your shoulders. Then, lift your legs and bend your knees into a tabletop position, stacked over your hips at a 90-degree angle. Exhale, engaging the core, as you slowly lower the opposite arm and leg (left leg and right arm), hovering them above the floor. Return to the starting position. Repeat on the opposite side (right leg and left arm). Repeat for 5 repetitions on each side.

Reverse crunch

Lie on your back with your legs lifted into a table-top position. Then, bring your knees into your chest, lifting your hips off the ground while keeping your knees bent. Make sure not to use momentum when bringing your legs toward your chest; instead focus on crunching the low abs to lift your hips off the ground. Perform 10-12 repetitions.

Leg raises

Begin in the same starting position as the flutter kick, lying on your back with your legs straight up toward the ceiling. Slowly lower them in a controlled manner squeezing your core until your feet are hovering about six inches above the mat. Hold this position for 10 seconds, and remember not to arch your back! If you feel your back arching, raise your legs back up slightly toward the ceiling until you find the angle at which you can hold for 10 seconds while keeping your back on the mat.

This article was originally published on TODAY.com