You’ve probably heard the phrase “engage your core” at least once in your life even if you’ve ever seen an exercise program, read a fitness magazine, or stepped foot in a gym. Sometimes it’s gently encouraged, while other times it’s yelled while you’re sweating out your last rep.

However, you may wonder what your core is, what it means to engage it, and how to do so.

The core consists of the muscles surrounding your trunk, including your abdominals, obliques, diaphragm, pelvic floor, trunk extensors, and hip flexors.

Your core provides stability to the trunk for balance, plus movements like lifting weights and standing up from a chair. It also provides mobility to allow your torso to move as needed, such as when you reach for your seatbelt or swing a golf club (1, 2, 3).

Furthermore, core muscles are involved in normal daily activities like breathing, posture control, urination, and defecation (4).

Every time you exhale and inhale, your diaphragm plays a large part in allowing air to flow into and out of your lungs. When you sit up straight, your core muscles contract to keep your trunk upright. When you use the bathroom, they’re there to start and stop your business.

This article discusses what the core muscles are and their role in trunk stability, as well as reviews core exercises that you can incorporate into your workout regimen.

woman in plank position on yoga matShare on Pinterest
Drazen/Getty Images

Your core muscles are comprised of several muscle groups.

Rectus abdominis

The rectus abdominis, also known as the six-pack muscle, attaches from the lower ribs to the front of the pelvis. Statically, it stabilizes your trunk. For example, when you’re doing pushups, it keeps your pelvis and trunk level.

The primary movement it performs is bringing the shoulders toward the pelvis, such as when you sit up in bed or perform a crunch.

Internal and external obliques

The internal and external obliques attach on the lateral sides of the trunk from your ribs to your pelvis. Statically, they provide stability to the front and sides of the trunk.

Their primary movements involve trunk rotation, such as when you swing a baseball bat, and side bending.

Transverse abdominis

The transverse abdominis attaches from the lower spine under the ribs and around the body to the rectus abdominis. It’s the deepest of the abdominal muscles, and its job is to tighten up and provide support to the spine.

Pelvic floor

The pelvic floor muscles attach to the underside of the pelvis. These muscles start and stop the flow of urine and feces.


The diaphragm attaches to the underside of your lower ribs. It’s responsible for breathing in and out.

Back extensors

Your back extensors are multilayered muscles, including the erector spinae muscles, quadratus lumborum, and multifidi. They attach along the spine to the pelvis. Their job is to support the spine when you’re bending forward and lifting loads, such as during squats or the bicep curl.

Hip flexors

Hip flexors include the psoas and iliacus muscles. They attach to the spine and inside of the pelvis. They bring your legs toward your torso, such as when you do high knee exercises.


Your core comprises several muscle groups, including your abdominals, pelvic floor, diaphragm, back extensors, and hip flexors.

Below are basic abdominal stability exercises you can use to engage your core. They’re by no means exhaustive but helpful in understanding how to engage your core muscles.

The abdominal draw

  1. Lie on your back with your knees bent. This can also be done sitting up straight.
  2. Suck your stomach in, imagining bringing your belly button to your spine. You should still be able to breathe but may feel the muscles around your abdomen and sides tighten. Your back shouldn’t move — make sure it isn’t arched or pushed into the ground.
  3. Hold for 5–10 seconds. Relax. Repeat.

Watch this video for a walkthrough of the abdominal draw.

The plank

  1. Begin in a pushup position on your hands and toes. If this is too difficult, you can support yourself on your knees and elbows.
  2. Draw your abdomen toward your spine and keep your buttocks in line with your body. You should feel all the muscles in your abdomen working.
  3. Hold this position for 20–60 seconds.

It’s important to note that this exercise puts high loads on your spine. If you have back pain, it’s advisable to refrain from this exercise.

Watch this video for a walk-through of the plank.

The side plank

  1. Turn on your side with your elbow on the ground and one foot on top of the other.
  2. Lift your hip into the air so that your side is perpendicular to the ground and you’re supporting yourself on your forearm and the side of your foot.
  3. Maintain good alignment of your feet, hips, and elbow. Also, keep your shoulder over your elbow. You should feel the obliques in your lower side working.
  4. Hold this position for 20–60 seconds.

Watch this video for a walk-through of the side plank.

The bird dog

  1. Kneel on your hands and knees as if you’re a table.
  2. Flatten your back without arching up or sinking in.
  3. Start by reaching one arm out in front of you so that it’s even with your head and torso.
  4. Then extend the opposite leg out, in line with your torso and arm. Make sure to keep your hips facing down toward the floor, rather than turned out toward the side. You should feel the muscles in your abdomen and back working.
  5. Hold for 5 seconds, then repeat with the opposite arm and leg.

Watch this video for a walk-through of the bird dog.

The dead bug

  1. Lie on your back with your knees bent and feet flat.
  2. Tighten your abdominals and keep your back flat as you lift your knees so that your hips and knees are bent at a 90-degree angle.
  3. Slowly tap one toe to the ground and return.
  4. To increase the difficulty level, extend your arms straight up over your shoulders. As you lower one foot down to the ground, reach the opposite arm back overhead, keeping your lower back on the floor and your ribs pulled in.
  5. Only extend your leg as far as you can while keeping your back flat.
  6. Return and switch sides.

Watch this video for a walkthrough of the dead bug.

The bridge

  1. Lie on your back with your knees bent.
  2. Keep your trunk and pelvis together as you squeeze your buttocks and lift them off the ground.
  3. Hold for a count of five.
  4. Relax and trunk to the ground. Repeat.

Watch this video for a walkthrough of the bridge.


There are multiple exercises to engage your core muscles. Basic ones include the abdominal draw, plank, bird dog, dead bug, and bridge.

Your core has multiple functions, including stabilization, balance, breathing, and bowel and bladder control.

Trunk stability

During activities like lifting something over your head, picking something up from the floor, or pushing or pulling an object, your core muscles contract to keep your trunk stable and support your spine (1).

These muscles are also important in weightlifting and athletic pursuits, such as judo, running, and soccer. Keeping your spine stable reduces the risk of injury (5).


Your core muscles aid in maintaining balance when you’re standing still, as well as when your balance is challenged dynamically (6, 7).

For example, when you are bumped into, your brain and trunk recognize this abrupt force and change in balance. They then react to help keep your body upright.

Your core muscles also support balance in activities like Olympic weightlifting, in which your trunk has to react and stay stable during changes in weight distribution.

Breathing and trunk stability

The diaphragm is a major muscle in control of breathing. It has an inverted “U” shape and lines your lower ribs.

It flattens as it contracts, allowing room for the lungs to expand when taking in a breath. Conversely, when the diaphragm relaxes, it compresses the lung cavity, forcing air out of the lungs similarly to how bagpipes work.

In addition, the diaphragm can isometrically contract to hold your breath when you’re straining when lifting something heavy. This action supports the trunk to avoid injury and maintain stability (8).

Bowel and bladder control

The pelvic floor muscles help control your bowel and bladder, allowing you to urinate or defecate (or hold it if you can’t make it to the bathroom).

If these muscles aren’t strong, a condition called incontinence occurs. Yet, these muscles can be strengthened to help prevent or manage this condition in many cases.

Additionally, the pelvic floor and diaphragm muscles work in conjunction with the rest of the core to maintain spinal stability by increasing abdominal pressure at your spine (9).


The core muscles have multiple functions, including trunk stability, balance control, breathing, and bowel and bladder control.

You engage your core during a variety of basic scenarios. These include:

  • Sitting. Sit up tall with your back straight but not arched. Suck your belly button toward your spine. You can also tighten your stomach as if someone is about to punch you in the gut.
  • Breathing. Relax your abs, shoulders, and neck. Slowly breathe in, letting your stomach gently push outward. Try to minimize how much your shoulders rise (or shrug) toward your ears, as this means that you’re using accessory shoulder and neck muscles to breathe.
  • Weight lifting. Your core engages during resistance activities in which you’re holding weight in your arms, such as bicep curls, squats, deadlifts, and military press. You can also engage one side more than the other by doing single-arm or single-leg exercises.
    • One study of various exercises found the highest rate of voluntary core contraction with free weight exercises (10).
  • Cardio. Cardiovascular activities involve multiple movements in varying directions engaging the core.
  • Yoga. This popular practice involves the core in many movements, including planks, bridges, and side planks, as well as balance on one or both feet via positions like Tree Pose and Warrior Pose, among others.

You can engage your core while sitting or breathing. You also use your core extensively during weightlifting, cardio, and yoga.

Engaging your core means contracting your trunk muscles to provide support for your trunk in static positions and during dynamic movements of the extremities. These muscles are used for balance, lifting, pushing, pulling, and general movement.

A strong core helps improve balance, decrease the risk of injury, and support your spine during forceful movements.

Overall, your core muscles are involved in the stability and mobility of the spine. They’re the “core” of all movements that your body does throughout the day.