The core is a very broad term often used to describe the muscles around the trunk, including the abdominals and low back muscles. However, there is a very specific part of the core musculature, which is especially important from an injury prevention and rehabilitation perspective. This very important part of the core is the deepest layer of muscle in the midsection, also referred to as the ‘inner unit’ and it is comprised of four key muscles.
- Transversus Abdominis: Often referred to as the ‘TA’ for short, this is a flat sheet-like muscle which wraps around the torso from back to front and from the ribs to the pelvis. The fibres of this muscle run horizontally, so when it tightens it acts like a corset providing support to this entire region.
- Multifidus: This deep muscle runs up the length of the spine and has attachments onto each individual vertebra in the lumbar spine (aka low back). It helps provide stability to the spinal column. In continuing with the corset analogy above, the multifidus can be thought of as the strings that tie the corset together.
- Diaphragm: The diaphragm extends across the bottom of the ribcage, separating the thoracic and abdominal cavities. It serves an important function in both respiration and core stabilization. For the diaphragm to function optimally, it needs to provide stability and allow for respiration simultaneously.
- Pelvic Floor Muscles: The pelvic floor is a muscular sling, which stretches across the bottom of the pelvis, both from front to back and side to side. There is a close association between the pelvic floor and the transversus abdominis (TA), such that a contraction of the pelvic floor can help to facilitate a TA contraction and vice versa. A pelvic floor contraction is also important to maintain the abdominal contents within the abdominal cavity against the increased intra-abdominal pressure created by contracting the other muscles of the inner unit.
The muscles listed above need to be able to work together for the inner unit to function well as a unit and to provide stability in the lumbo-pelvic region. They support a healthy posture, and should turn on in anticipation of movement to help protect the low back. For example, before bending down to pick something up off the ground, the inner unit should turn on automatically. However, in people with a history of low back pain, there is often a delay in this anticipatory function and atrophy in these very important muscles. This is why the inner unit needs to be retrained to work properly after low back injuries in order prevent injury recurrence and persistence of back pain.
Physiotherapists are experts in this area and can help teach you how to re-train a healthy core. If you are currently experiencing low back pain or have had a previous low back injury and want to prevent a recurrences, please do not hesitate to book an assessment with one of our experienced registered physiotherapists. Contact us today!
Written By: Reanna Montopoli, FCAMPT Physiotherapist