When we discuss the core, we mean the trunk and the core muscles around it that support it. A stable core is one that doesn't sag or sway when the movements are performed by the arms, legs, or larger trunk muscles.
Spinal stabilization is composed of 3 subsystems
Stability can be defined as your ability to control movement of a joint around a neutral zone. Movement in this zone is accompanied by minimal resistance by soft tissues. Movement outside this zone is limited by ligament and muscle length and can be accompanied by discomfort due to stretching of these structures. Spinal instability can lead to back pain, poor posture, arthritis, disc degeneration, and nerve root irritation.
Spinal stability is
dependent on the structure of the spine (the boney alignment,
and the ligaments that hold each segment together). The muscular
support actively holds the spine in an optimum position (neutral
of the trunk may be divided into "mobilizers" and
"stabilizers". Mobilizers of the spine are the more
muscles that cross over multiple joints so that when they contract they
move many joints at once:
muscles are designed for quick,
powerful and explosive movements. Their capacity for
sustained activity is limited due to their muscle fibre type
composition. Therefore, their capacity to provide core stability is
primary deep stabilizers are the core muscles that go from spinal
segment to spinal segment:
fibre type the core muscles are
designed for long term,
prolonged use with a high capacity for endurance. They contract for
long periods to support us when we sit or stand for prolonged periods.
They control the fine movements that occur between vertebrae.
transversus abdominus is responsible for drawing in the abdominal wall
and increasing pressure within the abdomen thus stabilizing the spine
while the multifidus are responsible for finely adjusting vertebrae
with small movements. The pelvic floor muscles also play a role in
support of the spine. This middle layer of muscles provides the
majority of the low back stability by preventing excessive bending or
rotating of each vertebra. These are anticipatory muscles, meaning they
activate before any actual body movement occurs. With injury to the
lower back there is a delayed activation of the transversus abdominus
thus inhibiting the stabilizing function that it normally has. Injury
also causes a decrease in the level of activity of these muscles as
well as a loss of muscular endurance in these muscles. These changes can
occur within as short a period as 24 hours post-injury. It is important
to realize that these muscles will not reactivate on their own. Your
must retrain them to prevent recurring injury.
Other muscular systems also add stability to the spine: the latissimus dorsi and the gluteus maximus on the opposite side connect by way of the thoracolumbar fascia, the internal and external obliques and the hip adductors on the opposite side connected by way of the anterior abdominal fascia.
Neural control centres
provide sensory feedback from both
systems and are responsible for the timing of core muscles that support the
spine. When you go to open a heavy door, a coordinated, well timed
sequence of muscular contractions occur in your back to provide your
spine with the stability you need to open the door.
If you damage your back through a lifting injury or car accident, your ligamentous support system is damaged, therefore you need to use your active muscular support system (core muscles) to stabilize your spine. That involves not only strengthening but also coordinating and re-educating the surrounding musculature. The muscles' ability to contract and maintain stability depends on the speed and accuracy with which the information from joints and stretched ligaments is relayed. The important aspects of neural system development are therefore accuracy of movement, and speed of the reacting muscular contractions.
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