The spinal column consist of 33
vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused),
and 4 coccygeal (fused).
Injury occurs when the spine and its supporting structures
can not withstand acute or chronic forces (ie compression, distraction,
shear).
The curvature of the spine is preserved
in part by the ligamentum
flavum, which runs between the posterior aspects of the verebral
bodies. The paraspinous musculature, which runs anterior to the
spine, works to counter balance the bodies center of gravity.
Normally, the anterior aspects of the spine bears most to the
body's load in an upright position.
In 2006, Over 27% of adults (18 years of age and over) had
low back pain in the past 3 months. Over 14% had recent neck
pain.
U.S. Dept of Health and Human Services, Centers for Disease
Control and Prevention, National Center for Health Statistics,
Health, United States, 2007.
75% of elite athletes have complained of back pain at some
point in their careers.
Spencer CW III, Jackson DW. Back injuries in the athlete.
Clin Sports Med. 1983; 2: 191-215.
Gerbino PG II, Micheli LJ. Back injuries in the youn athlete.
Sport Med Arthroscopy Rev. 1996; 4 : 122-131.
More than 75 percent of disk herniations occur below T8. The
peak is at T11-12 where there is greater spinal mobility. Central
protrusions are the mast common.
Okada Y, Shimizu K, Ido K, Kotani S (1997) Multiple thoracic
disc herniations: case report and review of0the literature. Spinal
Cord, 35: 182-186.
 According
to McGill. relatively few low back injuries occur from a single
event. He proposes a back injury most often occurs after a series
of excessive loads gradually and progressively reduced tolerance
to tissue failure. He further explains the injury process may
not always be associate with loads of high magnitude.
ACSM (2001), ACSM's Resource Manual for Guidelines for
Exercise Testing and Prescription, 4th ed, pg 117.
LBP Prognosis
Acute low-back pain (lasting less than 3 weeks) usually resolves
itself without any intervention
- 75% of individuals recover from acute low back pain within
3 weeks
- 90% of individuals recover from low back pain within 2 months
Chronic low-back pain (symptoms lasting more than 7 weeks)
- number one cause of disability in the United States
- the longer an individual suffers from CLBP, the worse the
prognosis
Carpenter DM, Nelson BW (1999). Low back strengthening
for the prevention and treatment of low back pain. Medicine and
Science in Sports and Exercise Jan; 31(1): 18-24 .
Low Back Debate
 McGill
condemns the use of isolated
lumbar spine machines claiming the compressive forces of
these devices can cause disc herniation based on a pig spine
model. Nelson recommends the use of these devices and has successfully
used these devices to treat chronic low back pain. See Erector
Spinae Weakness. McGill suggests certain exercises and movements
that flex the spine through the full range of motion be should
be eliminated although he admits several thousands of
cycles under a load to full range of motion are required to produce
disk herniations. It can be argued that potential injury would
be prevalent in this situation not due to full range of motion,
but rather due to overtraining or lack of progressive
adaptation. Nelson explains the avoidance of full range of
motion during exercise is a short term solution which promotes
deconditioning and consequently deterioration of the joint structures.
Eric Serrano, MD, (ExRx.net medical advisor) suggests these machines
can be useful in the early stages of rehabilitation. Dr. Serrano
prescribes more functional movements as the patient progresses,
introducing transverse / multiple plane exercises in the later
stages, particularly with athletes. Also see adaptation
criteria and Dr.
Nelson's audio interview.
McGill Stuart (2002), Low Back Disorders, pg 55. Textbook
Nelson, B.W., O'Reilly, E., Miller, M., Hogan, M. Wegner,
J.A., Kelly, C., (1995). The clinical effects of intensive, specific
exercise on chronic low back pain: a controlled study of 895
consecutive patients with 1-year follow up. Orthopedics, 18(10),
971-981.
Nelson, B.W. (1993). A rational approach to the treatment
of low back pain. J Musculoskel Med, 10(5), 67-82.
Sitting and Occupational Low Back Pain
Sitting by itself does not seem to increase the risk of low
back pain or sciatica. The risk, however, increases while sitting
in awkward posture, sitting for more than half of the workday,
and during whole body vibrations, such as in certain vehicles
and on machinery.
Eur Spine J. (2006). Association between sitting and occupational
LBP.
Walking & Low Back Health
Walking may benefit low back health by imposing a rotational
torque on the spine at an estimated 8° of rotation. The vertebral
disk undergoes this torque along with a slight degree of compressive
force from the upper body weight and contraction of the trunk
muscles. The torque is impressed on the annular fibers of the
intervertebral disks enhancing their rigidity.
Cailliet M (1996). Low back Pain. Soft Tissue Pain and
Disability, FA Davis Company Philadelphia. 3; 153-155.
Training Frequency
Training once per week may be just as effective as training
two or three session per week when measuring isolated lumbar
strength.
Graves JE, Pollock ML, Foster D, Leggett SH, Carpenter
DM, Vuoso R, Jones A (1990). Effect of training frequency and
specificity on isometric lumbar extension strength. Spine;15(6):504-9.
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Mediolateral
curve of the vertebral column.