Core as a Cylinder

Pilates Principles #2: Deep Core Activation

Deep Core Activation

Deep Core Activation is the foundation of all Pilates exercises.  It is the key to all effective, elegant and balanced movement.

Deep Core Activation is realised by:

  • Multifidi
  • Transversus abdominis
  • Diaphragm
  • Pelvic Floor


Without the stabilization provided by the deep core muscle system that surrounds the lumbar spine, the delicate spine would not be able to withstand the forces exerted by the lower limbs.

In all actions: standing, bending, sitting, walking and running, the pelvis and the lower spine need to work together to stabilise the rest of the body.


The core is a cylinder comprising of the:

Tranversus Abdominis at the front and the sides and the

Multifidi at the back.


This forms a cylinder which is closed off at the top and the bottom by the

Diaphragm and

Pelvic floor



Core as a Cylinder



All these muscle groups work together as a cohesive whole to


the pelvis and lumbar spine when they are

placed under stress

by activities such as

lifting, bending, twisting, stretching, walking, running & jumping



Note that core activation is not the same as abdominal strengthening.  It’s possible to have strong abdominal muscles but a weak core.    The abdominal muscles consist of the Internal oblique Abdominal, the External Oblique Abdominal and the Rectus Abdominis



Note that despite appearances and the assured nature of the facts presented by some teachers and many anatomical texts, it’s not possible to totally isolate one or other muscle in any particular movement.  We are in the business of learning and teaching movement, not isolating muscles.  Muscles work together as a system and that system includes other tissues including bone, fascia and other connective tissues.



Deep Core: awareness raising exercises

This is not intended to be an exhaustive list, rather these are examples of exercises that can be used to raise awareness of sensations that can then be used to guide our Pilates Practice.


To create the sensations associated with an active core

  • Fingers on abdominals: deep exhalations and inhalations.
  • Quadruped abdominal exercises:
    • pregnant cat
    • cow (of cat/camel)
  • Standing multifidus manipulation whilst hinging from our ankles as a pivot point.


Abdominal exercises

  • Abdominal curls
  • Oblique abdominal exercises


To promote the sensations of Lumbo Pelvic Stability

  • Marching
  • Toe taps
  • Opposite arm/leg reach



Deep Core: Anatomy 


Muscles attach to the back of the vertebrae all along the spine, from the scarum to the axis.  They consist of three bundles:

  • The rotatores pass to the lamina above (1 & 2).
  • The multifidus pass to the spinous processes of the vertebrae that are located two to four levels above (3).
  • the Semispinalis muscles, the most superficial, pass to the processes of the vertebrae that are located four to six levels above (4-6).

When viewed from the back, the transversospinalis form a “chevron” pattern along the rear of the spinal column.  They create spinal extension (the diagonal fibres), side bending (the fibres that run from medial to lateral) and rotation (from anterior to posterior).



Transversus abdominis

The TA actys like a corset and narrows the circumference of the waist.  It’s the second part of our chain.  Because of it’s attachment to the thoracolumbar fascia around the spinal column, it acts in conjunction with the transversospinalis muscle group to help create axial lengthening of the spine by squeezing the spine like a sausage skin.

The TA is the deepest of the four trunk muscles: transversus abdominis, internal oblique, external oblique and rectus abdominis.  It attaches to the front of the pelvis (iliac crest and inguinal ligament).  At the back it attaches to the five lumbar vertebrae and above to the inner surface of the last seven ribs (where it “interdigitates”) with the diaphragm and at the front, the two halves are attached to the linea alba in aponeurosis: a sheet of pearly white fibrous tissue which takes the place of a tendon in sheet-like muscles having a wide area of attachment.

Contractions of these horizontal fibres results in a reduction of the diameter of the abdomen.  When the anterior aponeurosis is fixed (held stable) it increases lordosis (curvature of the lumbar spine).



Pelvic Floor

The Pelvic floor works with the diaphragm to form the upper and lower ends of the cylinder create by the transversus abdominis and the transversospinalis.

It’s main function is to hold the abdominal contents again gravity and to control what comes out and when.  That is, as well as holding parts of the pelvis together, the pelvic floor has muscles that control fluid flow.

A strong and effective pelvic floor is necessary o give birth and a healthy pelivc floor facilitates better sexual functioning in both men and women.

The pelvic floor is sometimes called the pelvic diaphragm because t contracts and relaxes in relation to the diaphragm when the transversus abdominis is active.



Iliopsoas and Quadratus Lumborum 

The Psoas, or iliopsoas as it is also called (because it joins the upper femur with the same tendon), is attached to each vertebrae (not the disks) of the lumbar spine.  It runs in front of (anterior to) the pelvis and atteches to the lesser trochanter of the femur.  There is a bursa at the front to the pelvis where the psoas bends over the bone to prevent friction.

It was thought that the psoas was a spinal muscle involved in increasing lordosis (anterior curving of the lumbar spine.  However, in part because this is a multi-articular muscle (passing over some 6 lumbar spinal joint joints and the hip and sacroiliac joints) it has a much more complex action.

It is responsible for: straightening (lengthening) the spine in conjunction with the posterior transversospinalis muscles.  It also pulls the lumbar spine into side bending flexion and rotation of the side opposite the contraction.

The Quadratus Lumborum originates from the posterior iliac crest and inserts into rib 12 and the transverse processes of the Lumbar Spine L1-L5.

It is comprised of both vertical and oblique fibres allowing it to pull rib 12 and all the others into side bending.  When the spine is fixed, it raises the pelvis to one side.  It is also an expiratory muscle.







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