YOUR CORE or 'INNER UNIT' provides the necessary joint stabilization for the spine.

Without your inner unit, we do not have an activate stress relief process to support our spine, pelvis, and joint structures in the body.

Stress on the body creates (in time) an environment that leads to many orthopedic injuries and muscle imbalance.

One active way we can to help reduce such stressors, improve posture and the general visual appearance, is to stop all crunch and/or sit-up type exercises until you become proficient at activating your inner unit.

With inner unit dysfunction being extremely common in today's working and exercising population, it is safe to assume that everyone needs to start with novice exercises, even the most elite of athletes.


Muscles of the Inner Unit

  • The basic inner unit consists of the following four muscles: „
  • Diaphragm  
  • Transverse abdominis
  • Multifidus „
  • Pelvic floor „
Inner Unit cross section

Transverse Abdominis

The transverse abdominis (TV) is the deepest, innermost layer of all abdominal muscles. Consider the TV as your body’s personal weight belt. When the TV contracts it causes hoop tension around your midsection like a girdle or corset.

The transverse abdominis will, if working properly, contract before any of your extremities move. If the TV does not tighten up, acting as a girdle around your waist, your spine and pelvis are at higher risk of injury.

If the spine is unstable the nervous system will not recruit the extremity muscles (outer unit) efficiently and assist with functional movement correctly. For example, if you bend over to pick up the laundry basket and your transverse abdominis does not activate properly, this leads to all stabilization occurring at the segmental (one-joint) level. This stress eventually leads to overload of the segmental stabilizers and—BANG! You have massive lower back pain.

This occurs because the segments of your spine tighten down but the gross stabilizer (transverse abdominis) does not leave the segments to work on their own. They cannot provide enough muscular strength at the segmental level to withstand such a movement.


Now can you imagine lifting weights, grabbing a suitcase off the conveyor belt, or reaching overhead to get down a box of heavy tapes? When the transverse abdominis does not work properly the joints will begin early degeneration, leading to many orthopedic problems. To activate the transverse abdominis (pictured above), draw your belly button up and in toward your spine. This activation should be done before bending over or reaching overhead, especially with heavy loads.


The next muscle we must look at is the multifidus. This muscle lies deep in the spine, spanning three joint segments. The multifidus works to provide joint stabilization at each segmental level. Each vertebra needs stiffness and stability to work effectively to reduce degeneration of joint structures.

Pelvic Floor

The pelvic floor is our next set of muscles that spans the area underneath the pelvis. It is important for the pelvic floor and the inner unit to work properly. In many cases because of operations such as hernias, hysterectomies, and C-section childbirth, the inner unit muscles have been cut, reducing communication to the pelvic floor. By doing simple yet important exercises we can re-establish communication, tighten and tone the muscle group, prevent or diminish incontinence, leakage, and pelvic dysfunction.


Each of these three muscles, plus the diaphragm, are the target of inner unit conditioning.


Basic Exercises to Improve the Inner Unit

4-point Tummy (Transverse) Vacuum (4PTV)

The 4PTV is great for isolating the transverse abdominis, for correcting “pooch belly,” and reconnecting to the nervous system. It is a valuable skill to learn for pre-surgery preparation, post-surgery rehabilitation and general trunk stabilization. Surgical procedures such as caesarean section and hernia, the muscles, nerves, and tissues are cut, causing a loss of neurological impulse (your brain tries to call your muscles to wake them up, but the muscles don’t answer!). Lack of neural drive to the core muscles is one reason for the belly hanging out. Certain exercises can help reconnect the nervous and muscular systems so your “pooch belly” gets the message from the brain loud and clear and pulls those muscles in.

Note: Using a dowel rod can help you keep good neutral exercise posture and provide biofeedback. (As the rod touches different parts of your body, it makes you aware of your body position.) If you use the dowel technique, place the rod along your spine, making sure the back of your head, upper back, and tailbone are in contact with the rod.


Get down on all fours as though you were going to crawl. Place your hands directly underneath your shoulders and your knees directly beneath your hips.


Inhale and let the transverse abdominis hang out toward the floor (diagram A)

Exhale, drawing the belly button in toward the spine. Avoid any spinal movement during this exercise such as contracting the glutes, hamstrings, or external rotators (diagram B).


Vertical Horse Stance (VHS)

The VHS integrates the stabilizer muscles of your spine with the other muscles of the inner unit.

Very much like the 4 Point Tummy Vacuum, the VHS targets the inner unit muscles multifidus, pelvic floor, transverse abdominis and diaphragm. After mastering the isolated 4PTV, it is important to then start to integrate supple movements to allow the nervous system to link spinal stability and movement.


Get down on all fours with your hands directly underneath your shoulders and your elbows slightly bent. Your knees should be directly beneath your hips at a 90-degree angle.


Raise your left hand and right knee approximately 1/4 centimetre off the ground (that’s about the thickness of a credit card. The right knee is also raised slightly off the matt. Hold this position for 10 seconds.

Repeat with the right hand and left knee.

Alternate back and forth until you have done the exercise for a total of 2 minutes. To help you with proper exercise duration, use a kitchen timer. Do not let your hamstrings flex the lower leg toward the ceiling. Ensure that your pelvis does not shift into the hip that is in contact with the ground.


Blood Pressure Cuff

Note: This exercise requires a blood pressure cuff.

A great integration exercise for the inner unit, lower abdominals, and lower extremities (your outer unit).


Lie supine (back down, face up) on the floor with your shoes off. Bend your hips and knees, placing your heels about 20 cm from the buttocks. Keep your spine in a neutral position. Place a blood pressure cuff under your lumbar spine. Pump the cuff up to 40 mm Hg and take a deep diaphragmatic breath.


Slowly exhale and draw your belly button in toward your spine.

Slowly slide the left leg out, away from the starting position. There should be very little movement of the blood pressure cuff needle. If the pressure on the cuff begins to increase or decrease by more than 5 mm Hg, stop the movement and slide your leg back to the beginning position. Make a note of the distance. The distance is now your ending point. The goal is to extend your leg farther out without the blood pressure cuff changing its reading. The farther you can extend your leg, the better the integration of your inner unit and outer unit. Repeat for the opposite leg.

Repeat for 10 reps at a slow pace for each leg. Do not rush this exercise, aim to do this exercise daily until you can alternate sliding each leg in and out, keeping the blood pressure cuff at 40 mm Hg.


After doing inner unit exercises for a while you should notice your lower abdominal region feeling tighter and firmer.

Although the exercises may seem simple from looking at the diagrams here, they are actually very technical and must be executed with exact precision. These exercises are only a small sample of the number of inner unit exercises available but, when done correctly, they are sufficient to make a noticeable difference in the way your body functions.

To get the most from the inner unit exercises shown here it is suggested that the exercises be done 3-4 times per week as an individual workout. To get the best results from these exercises while continuing with a traditional gym program,  suggest you stop all crunch and sit-up exercises and replace them with the exercises demonstrated here.

Always perform an inner unit exercise as the last exercise of your training session, i.e. perform one exercise after each workout. Alternate through the exercises, giving either the 4 Point Tummy Vacuum or the Vertical Horse Stance exercises a go after each training session.

Note: More advanced Horse Stance exercises are always available in a specific client program, to book a consultation & assessment please contact


Join us next month for a look at the outer unit and the relationship it has between the inner unit and function.




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Clinical Anatomy of the Lumbar Spine. Churchill Livingstone.
Therapeutic Exercise. For Spinal Stabilisation in Low Back Pain. Churchill Livingstone.
3. CHEK, P. (1999)
Scientific Core Conditioning Video Correspondence Course. Encinitas: C.H.E.K Institute.
4. CHEK, P. (1999)
The Golf Biomechanic's Manual -Whole In One Golf Conditioning. Encinitas: C.H.E.K Institute.
5. CHEK, P. (1994)
Scientific Back Training Video Correspondence Course. Encinitas: C.H.E.K Institute