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What is the Core?

     This is Lesson 1, of a 12 Point Education Series for the clients of the Marchant Training Method. This is a preview of the information taught to those who make the committment to change their health and fitness, and the commitment we make back to teach them how to inform and inspire themselves towards their dreams and goals.

The Core Level One: Structure & Function

     The “Core”, we hear all about, but do we know what and where it is? In this lesson we will clear up any and all confusion surrounding the sometimes ambiguous term “the core”. You may even come away with more knowledge about the core, than some fitness professionals.

Lesson 1 Learning Objectives:
- Define the 5 muscles that make up the core.
- Describe how to test for core function and strength.
- Detail how to exercise 3 of the core muscles in detail.

What is the “Core”?

     The core is a modern term used to describe the muscles that surround the midsection and support the lower back. There is often, incomplete and confusing information handed out whether from books, magazines, media, or even from health professionals. We will clear all of that up in this lesson.
     The body is one functional unit with many muscles all working together. As the saying goes, “No man is an island”, so is true with the human musculature system - No muscle is an island.   Each muscle of the body works concurrently with other muscles (synergists, antagonists and stabilizers). Muscles work in groups in order to complete sophisticated movement patterns repeatedly everyday. You might think that your movements do not meet the requirement of being sophisticated, but lets consider normal movement: walking, opening a car door, sitting into a chair, standing from either a seated or kneeling position, they all require a sophisticated pattern of movement. These movements call for specific amounts of mobility, stability, strength, coordination, and timing.

At the center of all movement (even in sitting) is the “Core”. The core is made up of five muscles:
- Transverse Abdominus
- Pelvic Floor
- Diaphragm
- Internal Obliques
- Multifidus

     Don’t worry, we wont be taking an anatomy & physiology test at the end, but I find it important for us to briefly discuss which muscles are involved and their basic function. By doing so, we might have a clearer picture in our mind of what the core is and how we can start to strengthen it. Think of the core like a rectangle canister. Each side of our canister must be functioning and strong to maintain it’s composure and posture. In this illustration of a canister, the muscles of the core are represented in the following way (figure 1):

Transverse Abdominis - the front
Pelvic Floor - the bottom
Diaphragm - the top
Internal Obliques - the left & right sides
Multifidus - the back

     Out of these five muscles there are only three that need our conscious attention: the Transverse Abdominis, the Pelvic Floor, and the Diaphragm. The other two will not need the same attention, but we will discuss them as well. Lets start to by taking a deeper look into these muscles.

Transverse Abdominis - The Front

     The abdominal wall is made up of three layers. The deepest and most influential is the Transverse Abdominis (TVA), also called the Transversus Abdominis. It acts as a girdle to “hold in” all the internal organs. The TVA is attached to the upper part of the rib cage down to the top hips. It sits behind the rectus abdominis - aka The Six-Pack muscles. When these “Six-Pack” muscles are over-developed, tight, and shortened, the TVA becomes weakened.

The Function of the Transverse Abdominis:
- The main stabilizer of the midsection.
- Supports good posture.
- Keeps internal organs in place.

The Consequences of a weak Transverse Abdominis:
- Bad Posture and movements patterns.
- Lower back and hip pain. (it may eventually work it’s way down to the knees & ankles).
- Incorrect and inefficient breathing.
- Hernia.

The Possible causes of Transverse Abdominis weakness:
- Surgery (c-section or any surgery where the stomach muscles are cut).
- Sitting too long & too often (Sensory Motor Amnesia).
- Poor food choices causing inflammation.
- Low back injury.

How to contract the Transverse Abdominis:
“Pull” in the belly button (no “crunching” exercises needed)
(please refer to the accompanying video for more details and instruction)

Pelvic Floor - The Bottom

     The Pelvic Floor Muscles (PFM) act like their name - a floor. This is where we literally get our “grounding” just like a floor would provide. The PFM offers a connection between the two legs and provides the stability while they move. Without a properly functioning PFM we would “fall out” of balance, coordination, and posture. It has the thickness of your hand and is shaped like a hammock.
     The Pelvic Floor is not a glamorous set of muscles, but deserves as much, if not at times, more attention than the biceps, shoulders, or glutes. This muscle is attached from the back by the tailbone to the front by the pubic bone, and to the sides next to the insides of the hip socket. It surrounds both the genitalia and anus. The PFM, like the TVA, are made up of three layers. The deepest 1st layer is not within conscious control, while layers 2 & 3 are. These two layers are responsible for the support of the organs of the pelvis and bladder. All of these muscles receive their nerve and blood supply from nerves and arteries that originate out of the tailbone, so any injury to any part of the tailbone may affect the function of the Pelvic Floor. These last two layers are also responsible for urethral and rectal control.

The Function of the Pelvic Floor Muscles:
- Stabilizer of the core, and lower extremities during both movement, standing, or sitting.
- A co-worker to the Diaphragm during breathing.
- Supports the bladder, vagina, rectum, and the inner organs of the abdomen.
- Maintains proper control and release during urination and bowel movements.
- Provides both voluntary and involuntary contractions for sexual function.

The Consequences of weak Pelvic Floor muscles:
- Bad posture and movement patterns.
- Lower back or hip pain.
- Incorrect and inefficient breathing.
- Hemorrhoids and prolapses.
- Incontinence (urethral or rectal) or inability to control gas.
- Sexual performance complications.

The Possible causes of Pelvic Floor weakness:
- Pregnancy.
- Surgery (episiotomy, prostrate, etc.).
- Sitting too long & too often.
- Poor food choices causing constipation.
- Medications (some medications can over-relax Pelvic Floor muscles, check with your doctor or health care provider).
- Physical or emotional trauma.

How to contract the Pelvic Floor Muscles:
“Lift” or contract these muscles as if you needed to stop yourself from using the restroom - both urination and defecation.
(please refer to the accompanying video for more details and instruction)

Diaphragm - The Top

     The diaphragm is most commonly known as the breathing muscle. It’s main purpose is to contract an relax while breathing, and can actively assist in deeper more oxygenated breathing. When we do not use this muscle while breathing, we end up chest (Thoracic) breathing and begin to hyperventilate. For core function, the diaphragm works together to complete the top portion of the core “canister”, and it keeps the appropriate abdominal (intra-abdominal) and chest (intra-thoracic) pressure. When incorrect pressure is keep in one of these two cavities, the result could be too much out the bottom causing a hernia, or too much out the top (intra-cranial) possibly causing one to pass out or to even have a stroke.
     The diaphragm is often not thought of as a trainable muscle, but it, like all muscles, must be keep active and strong. Its strength lies in its endurance ability. It’s form resembles a parachute,  and should contract up and down as we breathe. It sits right below the lungs and drapes like a blanket over the upper organs of the midsection.

The Function of the Diaphragm:
- Primary muscles used in breathing
- Stabilizes core by connecting the chest with the abdomen.

The Consequences of a weak Diaphragm muscle:
- Incorrect and inefficient breathing - poor intake/regulation of oxygen and carbon dioxide.
- Inability to properly stabilize the core.
- Poor control of the chest and abdomen.

The Possible causes of diaphragm weakness:
- Bad posture
- Sitting too long & too often
- Chronic Hyperventilation.
- Fear pattern breathing (emotional bracing).

How to contract your Diaphragm muscle:
Breathe in and out correctly for the exercise or movement you are doing.
(please refer to the accompanying video for more details and instruction)

Internal Obliques - The Sides (left & right)

Help us to rotate left and right. We work this muscle best when we twist, turn, or stabilize to not.

Multifidus - The Back

For our purposes, consider this muscles as being your lower back. When the other core muscles do not do their job effectively, the Multifidus is easily over worked.



What does the core do and when does it do it?

     The core is used in the following situations: Standing, walking, squatting, bending, lunging, pushing, pulling, and twisting. It is basically used in everything the body does. The few times when the core does nothing: sitting on the couch and sleeping. In sleep it gets to rest, in sitting it gets weak.

How can I test my core on my own?

1. Core Strength & Activation Test:
Start face down with a rolled up hand towel placed directly under the belly button. Keep your forehead on you forearms, and head straight. Gently pull your belly button up and away from the towel. Do not move the hips either forward (tucked in) or back (arched low back).

2. Standing String Test:
Tie a piece of string around your waist at belly button level. Keep your belly relaxed and make sure the string is snug, but not too tight. Pull in your belly button. The string should then become loose. You may then perform this test while doing a squat or and overhead reach. Place the string back over the belly button after each try.

3. Lower Abdominal Coordination Test:
Lay on your back, with both knees bent and feet flat. Place a rolled up hand towel in your low back. The towel should be above your belt line. It will be exactly where your belly button is, just on the opposite side. Lift both knees up to your chest. Start by lifting up the Pelvic Floor Muscles, then pull in the belly button. Next, gently push your lower back into the towel. This is not a test to see how strong you are - do not push down with all your strength. You want to keep some curve in the lower back. Keep the contraction of both the Pelvic floor and belly button while you slowly lower your knees, touching your feet to the floor. You should be able to keep the same amount of pressure on the towel the entire time. Repeat this test 3 times. You may see improvement by the third try.

(please refer to the accompanying video for more details and instruction)

Sometimes we may find that specific parts to our core is either not working, or we are having trouble identifying where on our body are the muscles listed above. Answering the next question may help you:

Why is my core not working?

As listed above, there might be many reasons for not being able to activate or feel you core working properly. For our purposes in this lesson we will cover three:

1. Sensory Motor Amnesia
Think of your muscles and brain to be like a room with motion sensor lights. We someone is moving in the room the light stays on, when there is no movement the lights turn off. Our bodies, like this analogy, try to conserve energy in the same way. If we don’t move it, we lose it. When a muscle goes for long periods of time not being used, the brain shuts off sending messages to that muscle on how to contract and function.
If you are having trouble activating these muscles of the core (or any muscle or the body), it could mean that you need to “turn on the lights” of those muscles. It can take time, but if you are diligent, they will start to work again. Other factors like pregnancy, surgery, or injury can create this amnesic affect.

2. Misalignment of Spinal Posture
It’s all in the angle. Think of your spine like you would for a golf swing - 1 degree off on a drive and you’re in the ruff. That means, that for every 1 inch we are misaligned we will not only experience aches and pains, but our ability to contract our core properly will be diminished. This misalignment is often caused from sitting too long, but accidents or injuries can also be a cause. Out of all the things we put our bodies through, sitting may be the most torturous for the back.

3. Nutrition and Lifestyle
More of this will be covered in Lesson 2. In brevity, what we eat can and will at times inflame the stomach and small intestine, cause bloating and create the inability to properly contract the core. Also, in regards to body fat, our food choices, stress levels, and sleep habits all play role.

How can I find out if my spine is relatively straight and then find the right posture for a more functional core?

First we need to ask and find out - “Am I able to find Neutral Spine Position?” There are many ways to test and measure this, for our purposes we will start by using a simple wall test:

The Wall Test:

- Stand with your heels 6-12 inches away from the wall.
- Place your tailbone on the wall first. You must maintain contact of the tailbone throughout the entire test.
- Next place your shoulder blades on the wall. You must maintain the contact of this part of your back throughout the entire test.
- Place your hand, palm out, in the “small” of your back. Your hand should rest right above your belt line. Your hand should fit snugly between the wall and your back. Make adjustments as needed to attain this. If your hand cannot fit - you have too little low back curve (flat back). If you hand can slide through untouched and you might even be able to get most of your forearm through - you have too much low back curve (hyperlordosis). Keep your hand there for the next step of the test.
- For the final part of the test, place the back of your head on the wall. You will to tuck your chin, and glide your head backwards. You must also keep your mouth closed and be able to look straight ahead. Do not force this position. If you cannot reach, there is no need to strain your neck. The inability to effortlessly (key word) touch the back of your head to the wall, implies that you might need some joint mobility and corrective stretches to put your spine back into its functional and strongest position.

(This is an easy yet effective way to find your own correct posture prior to any exercise.)

Others tests could include:

Active Leg Raise - Lay on your back, legs out straight, lock one knee, and raise it up. It should be able to reach 70 degrees (lined up with mid thigh on the other leg). Test the other leg - both legs should be equal or within a few degrees of each other.

3 Point Shoulder Reach - Stand up straight, use one hand at a time. First, by reaching overhead touch the top of the shoulder blade on the opposite arm. Second, reach over your opposite shoulder and touch the same shoulder blade. Third, reach behind your back and touch the bottom of that opposite shoulder blade. You receive 1 point for each correct touch. Test the other side. The goal is to get all three points, or to be equal in points on each side. Problems happen when one side gets a 3, and the other a 1.

(please refer to the accompanying video for more details and instruction)

Without a reasonably straight spine, it is very hard to properly contract the muscles of the core.

Which muscles will need mobility and stretching? and how?

     The following muscles are typically tight and immobile, when someone has less than optimal posture of the spine: Neck Flexors (front of neck) & Hip Flexors (front of hips). The neck flexors connect to the side of the skull, right behind the ear, and end on the top inside of the collar bone. When they are tight they pull the head forward. The hip flexors connect from the lower back, and the front end on the thigh bone. When they are tight they pull our belly and thighs closer together. This then will pull us back into the fetal position that we fought to work our way out of as infants. One of the leaders in Exercise Physiology, and creators of Corrective Exercise, described these two muscles as being the most problematic for human posture and movement when they are overly tight and active. He coined the terms: Upper Crossed Syndrome and Lower Crossed Syndrome to describe the affects these two muscles, among others, create in posture. A mobility, stretching, and strengthening program is always recommended in order to correct posture and restore core function. Here is a list of muscles and there respective Corrective Exercises:

Joint Mobility Movements:

Neck Flexors - “Chin Up” - 10 reps
Neck Extenders  - “Rooster” - 10 reps
Upper Traps & Mid Back - “Shoulder Circles” - 10 reps each direction
Mid to Low Back - “Tai Chi Twist” - 20 reps total (side to side)
Mid to Low Back - “Spinal Rock” - 10 reps (there are basic and advanced versions)
Hip Flexors - “Kneeling Hip Lunge” - 10 reps each side (there are basic and advanced versions)
Hamstrings - “Elevated Hamstring Twist” - 20 reps total (side to side)

Corrective Stretches:

Neck Flexors 1 - “Chin Up Hold” - Hold for 10-30 seconds.
Neck Flexors 2 - “2 &10 Chin Up” - Hold for the length of 1 exhalation, 5 reps per side
Chest 1 - “Bent Arm Hold” - Hold for 30 seconds.
Chest 2 - “Straight Arm Hold” - Hold for 30 seconds.
Abdominals - “Sphinx Pose” - Hold for 30 seconds (there are basic and advanced versions).
Hip Flexor & Thigh - “Kneeling Hip Lunge Hold” - Hold for 30 seconds (there are basic and advanced versions).
Hamstrings - “Elevated Hamstring Hold” - Hold for 30 seconds. (not everyone will need this stretch).

For best results: Complete this list of movements and stretches once per day.

(please refer to the accompanying video for more details and instruction)

How can I exercise my core?

     There are many core exercises, and none of them are ever wrong, although they may not be right to do for you. In an ideal training program, exercises are prescribed to the uniqueness of each client and in specific motor learning development. That developmental process is as follows:

First, you must be able to isolate your core, while on your back, not moving.

Second, you must be able to isolate you core, while on your back with movement.

Third, you must be able to isolate your core in a 4 point kneeling (hands & knees) position, not moving.

Forth, you must be able to isolate your core in a 4 point kneeling position with movement.

Fifth, from here you must be able to integrate your core into the 7 Primal Movement Patterns, starting with the squat. (Notice again, no “crunching” needed to work the core)

(The 7 Primal Movement Patterns are: Squat, Bend, Push, Pull, Lunge, Twist, Walk. The squat is a great movement to start with since we are required to perform a squat each time we sit down or get up.)

Basic Core Exercises (in ascending order of sophistication):

1. Core Hold Exercise:
2 sets, 10 second hold
2. Core Hold with Leg Kick-out:
2 sets, 10 reps per side
3. Bird Dog Lift & Hold:
2 sets, 10 second hold per side
Bird Dog Reach:
2 sets, 10 reps per side
5. Basic Squat with Core Hold:
  2 sets, 10 reps recommended

For best results: Complete this list of exercises 2-3 times per week minimum.

(please refer to the accompanying video for more details and instruction)

The Core: Is that it?

     No, that is not it. In this lesson we have covered only the Inner Unit to the core. This is the most inner layer of core muscles and must be addressed first in any fitness or corrective exercise program. In Lesson 3 we will cover the Outer Unit: its muscles and movements.

     That completes Lesson 1 of the Marchant Training Method Education Series - 12 Point Personal Training Plan?Corrective Exercise & Integration Process. If you have any questions please ask, and I would be happy to answer you to the best of my ability.

     If you have received this lesson from the Marchant Training Method and do not have the corresponding videos, please email us at, and we would be happy to send you those.

References and Resources:
- “Fitness for the Pelvic Floor” by Beate Carriere, PT
- “Anatomy of Movement” by Blandine Calais-Germain
- “Scientific Core Conditioning” by Paul Chek
- “Scientific Back Training” by Paul Chek
- “The Multifidus Back Pain Solution” by Jim Johnson, PT


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About Matt Marchant

Matt is a student of life and enjoys laughing, learning, and loving along with his wife and two year old son. He enjoys spending time in nature where he finds peace and rejuvenation, but most of all the simplicity that the outdoors provide. When he is not working he is playing, when he is playing he is working.


Holistic Health Practitioner (HHP) & Corrective Exercise Specialist (CES) Owner of Marchant Training Method, since 2001

Education & Certifications:

  • B.S. Degree in Kinesiology with a focus on Exercise Physiology from California State University at Fullerton in 2001
  • Holistic Lifestyle Coach (HLC) Level 3 from the C.H.E.K Institute
  • Exercise Coach from the C.H.E.K Institute
  • Circular Strength Training Coach (CST) from RMAX International
  • Circular Strength Training Kettlebell Specialist (CST-KS) Instructor from RMAX International
  • Holistic Coach from Journeys of Wisdom
  • PPS Success Practitioner from the C.H.E.K Institute

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