Core Instability

Core instability is the result of failure of the joint supporting structures to maintain adequate joint congruity.

When we make any voluntary trunk movement, it is the "prime movers", the rectus abdominus, obliques, erector spinae etc., (the large superficial muscles) that are responsible for the gross multijoint movement. It is beyond our conscious control that the small multifidus, transversus abdominus and pelvic floor muscles are working to stabilize our spinal segments to control this movement.

These stabilizing muscles work reflexively, automatically in a healthy individual. When the back is injured either through a sprain or strain, or disc herniation or disc degeneration, these stabilizing muscles are weakened or inhibited and therefore don't support your spine when demands are made upon it. When that support is not there, the large superficial muscles take over. This can lead to excessive stresses and shear on the joints in the spine. If these large muscles are used regularly to perform movements, without the support of the stabilizing muscles, these movement patterns become ingrained and can lead to chronic pain and joint dysfunction, or instability.

 When the large "prime movers" are used excessively to try to support one's spine they fatigue quickly resulting in burning pain, aching, and "trigger points". In order to relieve the pain in these large superficial muscles you must re-educate and strengthen the deep stabilizing musculature. 

graphic depiction of stability
graphic depiction of instability

In simplistic terms, you may think of most joints as a curved surface that fits inside another curved surface, or ball and socket in a few cases. With some injuries, the socket part of the equation essentially becomes larger, so the ball moves around excessively. This can create damage to the joint surfaces and put excessive strain on the ligaments that support the joints.

Some signs of core instability are as follows:

  • positive active straight leg raise test
  • back pain with prolonged standing
  • neck or back pain after exercising
  • inability to sit still without frequently changing position
  • simple household chores cause back pain

Clinical research has shown that injury to the spine can result in an increased "neutral zone", resulting in core instability. The ligaments and other passive (nonmuscular) structures will only provide support toward the end of range of a joint. The stabilizing muscles of the spine have the potential to compensate for this core instability if they are strengthened, and recruited appropriately.

Exercise ball exercises will assist in the retraining and strengthening of these muscles in a functional range.
If you suffer from back pain, prior to starting a lumbar stabilization program, you should be evaluated by your family physician and physical therapist (PT). Your PT will design a program specific to your condition and monitor your rehabilitation. If you try an exercise that exceeds your abilities to stabilize your spine, you may make your pain worse.

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