Refresh your understanding:

  • Osteitis Pubis is caused when adductors are overworked over time.
  • Your personal biomechanics (the patterns that fire your muscles/move your joints) lead to the OP mechanics (hip drop, pronation, anterior pelvic tilt, locked SIJ and knocked knees) that cause OP.
  • Your personal biomechanics must be corrected to stop overloading your adductors.
  • The Deep Front Line (DFL) is the foundation of your body, responsible for the stability and alignment of your entire body. The DFL relies on 6 biomechanical/functional systems (arches, glutes, core, SIJ/Pelvic Floor, Oblique Chains, Balance).
  • Dysfunction/lack of coordination in and between these 6 systems leads to the poor OP mechanics that cause OP.
  • By maintaining good alignment (centre of gravity) the load/force of movement can be evenly distributed across the entire length of the DFL (and therefore the body) rather than being concentrated in the adductors.
  • The arch ensures a stable foundation to your DFL. The glutes ensure that your hip (and therefore femur, the longest bone in your body) is safely secure in its socket.
  • The core’s role is to ensure the stability and alignment of the pelvis, lower spine (lumbar) and rib cage within the DFL.


A functional, mobile sacroilliac joint is necessary for basic movements like walking, running, squatting and changing direction. When the SIJ is locked the body twists and over rotates the spine, rib cage and hip to compensate for the lack of movement at the pelvis.

The Pelvis and Sacroiliac Joint: the very ‘middle’ of your body.

The pelvis is made up of 3 parts. There are the two sides of the pelvis (illiums) and the sacrum. The front of each illium connects at the pubic bone/pubic symphysis.


The back of each ilium connects to either side of the Sacrum, making two Sacroiliac joints (SIJs).

Each ilium also contains the socket for each hip joint. Left leg connects to left ilium and therefore left SIJ, right leg to right ilum and right SIJ.

Each leg can move in its own direction. That is to say, you can move one leg forward and one leg backwards at the same time (walking).

The pelvis sits at the centre of your body. It is the base of your spinal cord and the beginning of your legs. Pelvic stability is incredibly important to human movement. If you fail to stabilize your pelvis you are leaving both your hip socket and your lower back vulnerable, a big reason for the hip replacements and lower back injuries people experience.

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Sacroiliac joint and moving: flexibility vs stability


As the front foot lands, the back foot and leg stretches behind the body. The side of the connected to the back leg rotates forward (anterior) to assist this movement.


The front leg is stretched in front of the body as you take a step. The pelvis rotates backwards (posterior) to accommodate this movement.


From behind you can see that each pelvis must rotate in a separate direction.

If you  walk/run you  need to put one foot in front of the other. You lift your leg and stretch it forward. When your front foot lands, your back foot and leg is already stretching behind you.

Each side of your pelvis has to rotate in a different direction to accommodate each leg. Your front foot illium will need to rotate forward, your back foot illium backwards.

This is a challenging task. You’re asking each side of your pelvis to move in a different direction at the same time. This needs flexibility and mobility, specifically at the SIJ.

Form closure: Maximal SIJ stability, no mobility

puzzle sij-puzzle

The SIJs are unique joints. Each side of the illiium and sacrum contains a set of interlocking surfaces. Essentially each SIJ fits together snuggly like jigsaw pieces. This is called form closure.


The space between the sacrum and illium is minimal. Form closure provides maximum stability and is extremely useful when lifting heavy objects. The sacrum is the base of your spine so you want maximum stability in dangerous situations that threaten to sever your spinal cord!

Form closure however is not good when your running/walking. Whilst stability is required, you also need each illium to rotate in a different direction. This cannot occur if both illiums are locked securely together.

Pelvic floor contraction = Form closure = SIJ locked


The pelvic floor attaches to every part of the inside of your pelvis. When the pelvic floor contracts it pulls the sacrum and both the illiums towards the centre, strongly locking the SIJ in form closure.

Force closure: Reduced stability, increased mobility

Force closure is the method of SIJ stability we use when we require movement and flexibility.  Unlike Form closure, Force closure uses the DFL, particularly our deep and superficial core, to stabilize the pelvis at the front where the core muscles reside.


As you can see, force closure creates space/releases the SIJ joint. It allows for the rotations needed in split leg movements such as walking/running.

Tranverse abdominis/Deep Core = Force closure = SIJ released


The transverse abdominis has broad attachments across the top of both sides of the pelvis. When it contracts it pulls the front of the two illiums together. As the front closes the back of each illium moves away from the sacrum, which releases the SIJ.

The Transverse abdominis activation (through the deep core activation) takes over responsibility for the sacroilliac joint to provide stability and mobility through force closure.

Force Closure vs form closure: Transverse abdominis (deep core) vs the Pelvic Floor

If you haven’t guessed already, an over tightened/locked pelvic floor plays a big role in the OP mechanic of a locked SIJ/Pelvis. What you might not appreciate is the battle your pelvic floor and deep core are engaged in under the surface.

The pelvic floor can operate fascially and muscularly. Operating fascially the pelvic floor absorbs load like a rubber band, stretching and elongating. This load is then distributed evenly across the body through the DFL.

When the pelvic floor is operating muscularly it is bracing, pulling the sides of the pelvis together into locked, form closed position.

Pelvic floor and Transverse abdominis: antagonists




The transverse abdominis and pelvic floor operate in an antagonistic manner (against each other). When the TA (deep core) contracts it pulls the front of the pelvis together to allow space/mobility at the back in the SIJs. When the pelvic floor contracts it pulls the back of the pelvis/SIJ together which locks the SIJ as it pulls the front of the pelvis apart.

If the two contracted together there would be a stalemate; no movement would occur in the SIJ. Deep core contraction sends a signal through the DFL to the pelvic floor telling it to relax muscularly and stabilize load fascially.

Conversely pelvic floor contraction sends a signal through the DFL to the core telling it to relax, the SIJ is being form closed and the TA should not contract because it will pull the SIJ out of form closure.


  • Deep Core contracts – front of pelvis  together for mobility (running)
  • Pelvic floor contracts – back of pelvis  together for stability (lifting).

Pelvic Floor Release and Deep core activation; a key skill

OP patients present with an over contracted, braced/locked pelvic floor. Your deep core has been dysfunctional so your body is in the habit of  relying on your pelvic floor for stability. Deep core activation can become difficult as the stronger over active pelvic floor prevents the deep core from firing.

It’s the connection and coordination of both systems that allows for healthy, effective pelvic rotations in running, jumping and changing of direction movements.

Learning how to actively release your pelvic floor, while activating your deep core is a key skill in overcoming OP and achieving Force closure. This will allow for healthy split leg movements such as running, jumping and changing direction. Your adductors will not be overloaded by compensatory pelvic rotations, twists and sways.

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