The “core” receives a lot of attention in the fitness and physical therapy world.  However, there is often confusion about what the term “core” really means. People often talk about the core as if it is one big muscle.

Predictably, when I ask my patients to show me where their core muscles are, they point to the large muscle in the front of the abdomen. This outermost muscle called the rectus abdominis is certainly the largest muscle in the abdomen.

However, the core actually consists of many different muscles in the trunk that extend from the base of your neck to your pelvis. 

The five predominate muscles that make up the core are:

  • Rectus Abdominis – Informally known as the “ab muscle” runs down the front of your abdomen from your ribs to your pelvis. In people with low body fat, it is often visible beneath the skin forming the “six-pack.”

  • Transverse Abdominis – This is a large band-like muscle that wraps around the front and sides of your trunk. It is very important for providing stability to your pelvis and spine.

  • The Internal and External Obliques – These muscles run diagonally between the ribs and the pelvis. They help to rotate and bend your trunk as well as provide trunk stability.

  • The Erector Spinae – This is a large group of long muscles that lie on each side of the spine and extend from the pelvis all the way up to the base of the skull. It plays a key role in keeping good posture.

  • Multifidus – This consists of a group of small, deep back muscles that runs right along the side of the spine and are very important for stabilizing the spine during movement. Research shows that people with low back pain often have significant atrophy and weakness in the multifidus muscles.

Other muscles that play a part in the “core complex” are your pelvic floor muscles, the diaphragm, the quadratus lumborum, and the gluteal muscles.

Although these muscles all have independent actions that like bending, twisting, or extending the spine, or moving a limb, they also work harmoniously to stabilize the spine and provide a base of support for all movement.

Weakness in any of the core muscles can lead to compensation of other muscles for stability and mobility. This in turn can lead to back pain, pain in the hips, knees, ankles, and even pain in the neck and shoulders. Core muscle strength is also essential for balance and posture. If you find that you’re struggling with your balance or maintaining an upright posture, those are 2 clear signs of core muscle weakness.

There are plenty of great exercises that can help strengthen your core muscles. However, to properly train these muscles it is important to understand how to engage these muscles. As I mentioned above, the core muscles need to work in harmony producing a co-contraction of these muscles at one time.

There are 2 ways that I find most effective in teaching my patients how to engage their core muscles. Merely sucking your stomach in is not engaging your core!

First, locate 2 of the predominant core muscles: The transverse abdominis and the multifidus.


Transverse Abdominis

To find the transverse abdominis:

  • Locate the anterior iliac spine, the bony protrusion in the front of the pelvis bone

  • Slide your fingers in about 1 inch

  • Now draw a breath in through your nose and then exhale through pursed lips

  • You should feel this broad, flat muscle tighten under your fingers



To find the multifidus:

  • Place your fingers on your spine

  • slightly roll your fingers off to one side

  • Now with your opposite leg, take a step forward

  • You should feel this rope-like muscle pop into your fingers as you take a step

With your fingers on those two muscles, you are going to work on engaging your core muscles.

The first method is to take a deep breath in through your mouth and then forcefully breathe out through pursed lips as if you are blowing out candles. You are looking for a simultaneous contraction of the transverse abdominis and multifidus muscles. 

Another method is to perform what is called abdominal bracing. With your fingers positioned as above, you are going to tighten up your trunk muscles to prepare as if someone is going to punch you in the stomach. Again, you want to feel a simultaneous contraction of both muscles. Additionally, you don’t want any movement to occur in the spine. If your spine rounds to the back, your abdominal muscles are overpowering your back muscles and if your belly pushes out to the front, your back muscles are overpowering your abdominal muscles. A good co-contraction of the core muscles does not result in any spinal movement. 

Once you get the hang of activating your core muscles, start by engaging these muscles while doing everyday activities such as reaching overhead into a cabinet, lifting a laundry basket, pushing a shopping cart.

In the gym, think about engaging your core before you perform an exercise. I call this “setting” the core. For example, before lifting a weight, engage or “set” your core muscles first. This will ensure that your body is in correct alignment, will give you a stable base in which you can perform the exercise correctly, and reduce the risk of muscle compensation and injury. 

Having a strong core will make you less prone to injuries, give you better balance, better posture, and more efficient movement whether performing your daily activities or even playing your sport. If you have osteoporosis, strong core muscles will protect your vertebrae from fractures and decrease your risk of falling and breaking your hip. 

Stay tuned for some of my favorite core exercises…or if you can’t wait…reach out to me to schedule an appointment and I can get you started on some key exercises to strengthen your core today. 


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