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1. Tight Hamstrings: In our modern world, we sit all day and our hamstrings are allowed to gradually shorten. If you are a runner, you never really stretch out your legs, so your hamstring is not stretched to its full length then either. Same with cycling. So what? Well tight hamstrings limit the mobility of the pelvis during activities such as bending and lifting, which in turn, requires that the lumbar spine take up the slack. Over time, this shift of motion responsibility to the lumbar spine will have the effect of increasing the mobility in one or two motion segments of the spine. (A motion segment is a disc plus the vertebra attached above and below.) The bottom line is that tight hamstrings are a causative factor to the unstable motion segment of the lower lumbar spine.
Much is said about the core. Almost everybody is offering "Core Stability Programs" now. So what gives? First one should understand the etiology of core instability:
2. Weak Abdominals: Our sedentary lifestyle again is responsible for the chronic weakness in our abdominals. There is a "stretch weakness" that exists as well with the abdominals being inhibited by the tight hip flexors and lower back muscles. This is referred to as a "lower cross syndrome". Tightness of hip flexors, coupled with weakness of the abdominals, especially the lower abs reduces the capacity of the trunk to successfully" stabilize" the lower back.
3. Progressive Failure of the Disc: Over time, as we age, it is very common for the disc itself to fail. Failure of the disc over time for several reasons including mechanical wear and tear, leads to excessive "play" in the motion segment making segmental instability a very real problem in many people. Coupled with tight hamstrings, weak abdominals and tight hip flexors, the unstable segment is put under more duress during motion, and as such bears the load of bending and lifting that should rightfully be borne by other structures.
4. Restricted Thoracic Spine: The T-spine is naturally restricted and over time becomes even more restricted resulting in reduced backward bending ROM and reduced ROM into rotation. The loss of this ROM leads to an increased demand for movement in the lower lumbar spine as well as the cervical spine.
When you put all this together with the fact that we have become a sedentary population, over weight and out of shape it is no surprise that the spine breaks down and structures in the spine fail.
Add to that one more fact:
5. Deep Muscle Inhibition: Pain the back is coupled with deep paraspinal muscle guarding, which in turn produces prolonged inhibition of those same muscles through a neurological mechanism. This gradual weakening of the deepest muscles adjacent to the spine are the final "nail in the coffin" of the unstable segment.
OK, so what about core stability exercises, do they work?
In short, the answer is "yes". What core exercises do is stabilize the spinal column by squeezing the organs against the front of the spine and wrap the the trunk in a casement of muscle that is rock hard front and back. The idea is to provide support to the spine through positive pressure that prevents the spine from collapsing or moving excessively under load.
Complementary to the core stability exercises, another key is to strengthen the deep spinal muscles, such as multifidus, in order to provide local stability on a segmental level.
So to summarize, in order to improve athletic performance, reduce segmental back pain, stabilize the lower back and the core, you need to do a good solid core program. I will elaborate on that in a later post.