Updated on February 17, 2021

Reviewed by Tara Laferrara, CPT

If you’ve ever worked out with a personal trainer or in a group fitness class, you’ve likely heard your trainer or instructor say something along the lines of: 

• Brace your core!
• Engage your abs!
• Stable midline! 

Other cues that trainers use include “pull your belly button toward your spine” and “flex your abs.”

Though there’s clearly a great assortment of ways to say it, all of these phrases mean the same thing: Engage your core. These phrases all refer to the action of tightening your core musculature to stabilize yourself or brace your body for a particular exercise. In this guide, you’ll learn what it really means to engage your core (it’s not just “sucking in”), how to do it, when to do it, and why it’s important.

Your Core, Defined

To know how to engage your core, you first have to know what your core actually consists of. Many people equate the term “core” with “six-pack,” but the anatomy of your core is more complex than you might realize. Your abs alone include four different abdominal muscles, and then there are all of your back muscles to account for. 

Here’s a look at the most important muscles when it comes to engaging your core:

• Rectus abdominis: The most well-known ab muscle, the rectus abdominis is the muscle responsible for the coveted six-pack. It’s a long, flat muscle that extends from your pubic bone to your sixth and seventh ribs. Your rectus abdominis is primarily responsible for bending your spine.1 
• External obliques: These are the muscles on either side of your rectus abdominis. Your external obliques allow you to twist your torso, bend sideways, flex your spine, and compress your abdomen.1
• Internal obliques: Your internal obliques lie just below your external obliques. They have the same functions.1 
• Transverse abdominis: This is the deepest layer of muscle in your abdomen. It completely wraps around your torso and extends from your ribs to your pelvis. Unlike the other ab muscles, your transverse abdominis isn’t responsible for moving your spine or hips, but it does stabilize your spine, compress your organs, and support your abdominal wall.1
• Latissimus dorsi: Commonly called your “lats,” these muscles run along both sides of your spine from just below your shoulder blades to your pelvis. Your lats help you stabilize your back, especially when extending your shoulders. They also contribute to your ability to twist side to side.1
• Erector spinae: You have erector spinae muscles on each side of your spine, and they extend the entire length of your back. These muscles are responsible for extending and rotating your back, as well as side-to-side movement. These are considered postural muscles and, to some degree, are always at work1.

Your hip muscles and glutes also contribute to core stabilization,1 but not quite as much so as the above muscles. 

You can gather from the sheer number of muscles involved that engaging your core isn’t as simple as it seems—but once you learn how to do it properly, you’ll find yourself pleasantly surprised at how much stronger you can become at compound lifts like squats, clean and jerks, and deadlifts.

What Does It Mean to Engage Your Core?

People learn from mistakes—in that sense, it might be easier to learn how to engage your core by understanding what not to do. Below are some common examples of failing to engage the core. 

• Your back arches while you perform shoulder presses or push-ups
• Your back slumps while sitting down
• Your lower back raises from the ground when trying to “hollow” your body
• You lean far to one side when performing a single-arm shoulder press
• You lose balance when performing single-leg exercises

All of the above scenarios exemplify a weak core in different ways. The first example—back arching when performing shoulder presses—is the easiest to dissect. When you perform a shoulder press, you should be able to extend your arms fully overhead while keeping your back in a neutral-spine position. If you can’t, your core muscles are weak, you haven’t learned how to engage and brace them, or perhaps you have a different mobility issue (discuss this with a doctor or physical therapist).

How to Engage Your Core

Engaging your core means bracing and tightening all of the muscles in your core2 —your four abdominal muscles, lats, paraspinal muscles, hip flexors, and glutes—to keep your spine safe and stable. Picture everything from your rib cage to your pelvis: It should all feel like a single, strong cylinder. 

It’s More Than Just “Sucking in” Your Stomach

It’s common to think that “engage your core” means “suck in your stomach.” But that’s actually pretty far from the truth; in fact, it’s quite the opposite. 

To engage your core, imagine that you are bracing yourself for a sucker-punch right to the stomach. You’re not going to suck in your stomach. You’re going to take a deep breath and tighten all of your abdominal muscles. It may be helpful to picture “zipping up” your abs—bringing your navel up and toward your spine. 

You should be able to continue to breathe when you engage your core: First, fill your belly, and then inhale and exhale, only allowing your rib cage to move. Your belly should remain tight and full after the initial breath. After that point, you should be able to see your ribs move in and out when you breathe.

It Starts With Your Breath

Breathing is perhaps the most important part of engaging your core because you must know how to continue breathing like normal while keeping your core tight. Every time you breathe, you have another chance to engage your core and create that strong cylinder of muscles from your ribs to your hips. 

Consider professional powerlifters and Olympic weightlifters. When these athletes wear weightlifting belts to help with their lifts, their stomachs often bulge over the top of the belt. This is not because they’re bloated or overweight—they are using their breath to push against the belt, which offers an additional layer of support for the spine. 

Between engaging their core muscles and the responding pressure of the belt against the core, powerlifters and Olympic lifters keep their spines safe while lifting extremely heavy loads. 

Why Should You Engage Your Core?

For starters, engaging your core decreases your chance of sustaining an injury while exercising.3 It creates a stable ring of musculature around your spine that keeps your vertebrae from flexing or extending too far, as well as from bending too far to one side or the other. 

Protection From Injury

Forcing your back into those positions puts excessive pressure on your vertebrae and can lead to injuries such as lumbar spondylosis.4 a condition that involves degeneration of your spinal discs or facet joints. This condition and a similar one—spondylolysis, or stress fractures in the vertebrae—are relatively common in weightlifters5 and athletes.6 Failure to engage the core during exercise has also been linked to shoulder and elbow injuries.7

Having core strength, which you can develop by bracing your core regularly (even while not exercising), can also help with chronic back pain.8 Basically, as one study puts it, “Core stability is a primary component of functional movement, essential in daily living and athletic activities."3

On top of injury prevention and functional movement, engaging your core during exercise may improve your workout performance, though it’s not entirely agreed upon in the scientific community because there’s a lack of research on the exact relationship between core stability and fitness performance.9

However, many weightlifters find that they can lift heavier weights when they brace their core, and runners often find that they have better posture and less pain in the neck and back when they engage their core during a run.

When Should You Engage Your Core?

Engaging your core is most important when there is potential for your spine to overly flex, extend, bend, or rotate.

Engage Your Core While Lifting Weights

Weightlifting may prove the most crucial time for engaging your core. When you bend at any of your major joints—specifically your shoulders, hips, knees, and ankles—there is an opportunity for spinal movement. Earlier, the example given was arching your back during an overhead press. Engaging your core can prevent any excessive arching of your spine. 

Another great example of when it’s important to engage your core is the deadlift. If you don’t brace your core before lifting the weight off the ground, your back may round and your shoulders may slump forward.

Taking a deep breath and tightening your tummy can help you keep your back straight and shoulder blades retracted. 

Engage Your Core During Cardio 

You don’t have as high of a risk for spine injuries during cardio exercise as you do during weightlifting exercise, because generally there isn’t as much opportunity to move the spine into dangerous positions. However, engaging your core during cardio can improve your posture and reduce any aches and pains you experience during or after cardio exercise. 

For example, when you go for a run, engaging your core can help you keep your chest high and your shoulders back. This can eliminate over-extension of your neck, a common problem that can lead to neck pain and headaches. Bracing your core during a run can also alleviate some of the pressure from your lumbar spine, reducing or eliminating any pain you feel there.

Engage Your Core During Ab Workouts

It can feel confusing to engage your core during ab workouts because there’s so much movement going on in the torso. However, you can look out for signs that you need to brace, the most common sign being hyperextension—also known as arching your back. 

When doing ab workouts, think of tipping your tailbone forward or squeezing your glutes. These two cues can help you reduce the lumbar curve of your spine and tighten your abdominal muscles.

Engage Your Core All Day

You can prevent poor posture (and chronic pain related to poor posture) by engaging your core throughout daily activities.

Practice bracing your core while sitting at your desk and while walking to and from your usual places.

You can also practice during other day-to-day activities, such as grocery shopping—try engaging your core when you reach to grab something from a high shelf. It’s good practice that will transfer to your workouts!

Practice Engaging Your Core

To get familiar with core engagement, start out with this bracing exercise. 

1. Lie face-up on the floor with your knees bent and feet flat on the ground. Extend your arms so they lie flat beside your body, with your palms on the ground.
2. Press your lower back into the ground so that your tailbone tips up slightly.
3. Inhale deeply, filling your belly. Once your belly is full of air, clench your abdominal muscles (while keeping your lower back pressed into the floor). 
4. Use your ab muscles to pull your belly button up and inward against your breath. 
5. Continue to breathe, filling your chest with air. Your stomach should remain full the entire time. 
6. Take three to five breaths, relax, and start the exercise over.