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Injury Prevention

Low back pain

Danny O'Dell explains the physiology and anatomy of the spine and some of the reasons for low back pain

The main purpose of the spine is to support the upright position and allow the body to move about during normal activities, including sports performance. The bony structure of the spinal column protects the spinal cord and its branching out nervous system. The individual vertebrae synergistically act as built in shock absorbers for the trunk. The vertebrae give the structural support to the spine.

Spine structure

The four curves of the normal back allow for flexibility and shock absorption. Included in the anatomy of the back are the facet joints where each vertebra meets. These control direction and the amount of spinal movement. The ligaments that connect the vertebrae together and the non vertebral discs are the final pieces of the spinal picture.

The non vertebral discs can rupture causing in some cases instant pain. They are sometimes considered the shock absorbers of the spine and allow for the great deal of flexibility inherent in the spine. Recent research by Stuart McGill and associates has disputed the 'shock absorbing' characteristics of the spinal column.

The spinal column is broken into five major areas:

  • The Cervical, beginning at the base of the skull, consists of seven vertebrae
  • The Thoracic (mid back) portion incorporates twelve vertebrae
  • The Lumbar region begins at the ending of the thoracic and ends with the lowest vertebrae attaching at the sacrum/pelvis. This is the area where most injuries occur. The L-5, S-1 segment is the most likely to be damaged of all the vertebrae in the back structure because it is the recipient of the greatest load bearing in comparison to the rest of the spinal column
  • Sacral-pelvis is the triangular bone that is inside the pelvis
  • Coccyx commonly known as the tailbone is the final part of the spine.

The lumbar region is the source of most of the lower back problems worldwide. In fact 8 out of 10 adults will experience lower back pain at some point in their lives. According to the National Strength and Conditioning Association about 5 million Americans suffer from acute or chronic back pain. This condition accounts for over 90 million lost production days a year in the United States alone. Just imagine what it is world wide!

The vertebrae of the lumbar region are larger than those of the cervical and thoracic areas. These vertebrae are responsible for supporting the body's weight. Extremely powerful lumbar muscles attach to this part of the spine.

The facet joints connect the vertebrae above and below one another and their shape restricts rotational movement of the lumbar spine. Flexion to the side, and extension and flexion of the lower back are all controlled by the lumbar facet joints. Amazingly, enough they are non-weight bearing and acting in a passive manner unless the spine is extended or arched backward. The slight curve of the lower back is produced by the shape of these vertebrae and this curve is different for each individual.

It should not be a surprise to learn that different postures alter the pressure on the inter-vertebral discs. Review the following chart and notice the tremendous differences of load supported by the back in the various body positions. Especially note the last entry 269% of body weight simply by not using good body position to lift an object of only 44 pounds.

Chart of pressures on the discs, expressed as a percentage of body weight, for various activities (NSCA, n.d.)[1]

Position/activity Disc pressure expressed as a % of body weight
Supine with both knees flexed 5%
Supine lying face up 25%
Side-lying 75%
Seated in a flexed position 85%
Standing 100%
Coughing or sneezing 105 to 135%
Walking 115%
Rotation 120%
Side bending 125%
Small jumps 140%
Laughing 140 to 150%
Standing and bending forward 150%
Lifting 44 pounds with the back straight and the knees bent (good body mechanics) 173%
Lifting 44 pounds with the back bent and the knees straight (poor body mechanics) 269%

Simply looking at the chart should be an important reminder to always use proper body mechanics whenever lifting objects. The 5th lumbar-1st sacral vertebral area (L5-S1) is the site that causes most of the problems simply because this joint area carries more weight than any other vertebral joint in the spinal complex! Most people, when they 'hurt' their back, generally hold onto this area when they stand up again that is if they can even stand up after bring injured. In retrospect it is easy to see why there are so many lower back injuries each year. It does not take a great deal of weight to cause grief, just poor positioning during a lift.

A few of the causes of low back pain are:

  • Poor overall posture
  • Slumped over, flexion of the lower back
  • Poor back posture " Stress and daily work habits
  • Riding in a vehicle for hours on end without a break especially in a vibrating vehicle which is very hard on the lower back
  • Lack of flexibility
  • Lack of flexibility in the hip joint which causes the back to compensate by flexing/bending forward
  • Deterioration of general physical fitness
  • Overweight
  • Lack of endurance in the extensor muscles of the lower back
  • If fit then incorrect lifting techniques being utilized
  • Rounded back when lifting " Bending forward during a lift
  • Failure to flex at the hip and substituting the lower back to make up for the lack of flexibility in the hip joint

Types of pain

Low back pain comes in two variations neither of which is good. Probably the more intense of the two will be the acute episodes. These come on suddenly and are very intense in the pain aspect. They will occur from doing something unusual, something that is not part of your normal activity or if it is normal then you are doing it the wrong way and become injured. Pain that arises generally lasts but a short time and then disappears.

Acute strains (muscle injury) and sprains (injury to the ligaments) are often times caused by lifting improperly, twisting while lifting, or even just twisting and by falling accidents. These injuries cause tearing, bleeding and irritation of the lower back muscles or the ligaments of the vertebral tissues in the lumbar region. Generally a specific incident can be identified as the culprit causing the pain.

The second type of back pain is more insidious as it may result from any movement for unknown reasons or by overdoing a normal activity. It also periodically reoccurs throughout a lifetime with no apparent reason. McGill and associates believe the tissues have reached the end of their tolerance for abuse and there is no more leeway so they become injured.

Chronic strains and sprains result from hours, days, or even years of undue stress placed upon the joints and muscles of the lumbar region. Poor posture stress in ones daily life or some common mechanical back problem, such as scoliosis, can predispose a person to chronic back injury and the associated pain.

Not only do the muscles and ligaments become injured but also so can the discs themselves. Degeneration tears or cracks may disrupt the normal state of these vertebrae discs. Sudden movements in a twisting manner can cause almost immediate pain. Once the discs crack open, the material inside them may begin to bulge outward onto the nerves of the lower body. Often times this causes numbness or weakness in the lower extremely.

Two common causes of bulges are sitting or standing in a forward slumped position or by twisting the torso while lifting an object. Which incidentally everyone does every single day! Can you grab the groceries from the back seat or trunk and lift them out with out twisting? Hardly! So this is an area that needs attention. Hint: turn with the hips, midsection and shoulders as a unit to avoid damage to the back.

In most cases, injuries are preventable if proper attention is paid to the attending causes. Education and maintenance of a strong musculature in the back and surrounding areas are the two crucial elements in the prevention of back injuries. Educate yourself about the causes of and the prevention of back injuries. During this process, learn the correct body mechanics of posture while standing, sitting, and laying down or in lifting objects. Learn correct back saving motor movements.

Exercise to maintain and increase the strength of your back and all the supporting musculature surrounding it. Specifically increase the strength of the core of your body, i.e. the area from the knees to the shoulders.

Constantly be aware of your posture and body mechanics as you lift or move about. Exercise appropriately and consistently each day to improve your physical fitness level. Follow the solid principles of exercise prescription of load, duration and frequency and warming up and cooling down for each session. Feed your body good food and liquids each day by following a solid nutrition plan.


References

  1. NSCA (n.d) Training and rehabilitation for the lower back. Quick series guide to:

Article Reference

This article first appeared in:

  • O'DELL, D. (2004) Low back pain. Brian Mackenzie's Successful Coaching, (ISSN 1745-7513/ 18 / December), p. 1-3

Page Reference

If you quote information from this page in your work then the reference for this page is:

  • O'DELL, D. (2004) Low back pain [WWW] Available from: https://www.brianmac.co.uk/articles/scni18a1.htm [Accessed

About the Author

Danny O`Dell is a NSCA Certified Strength and Conditioning coach from the USA. He is the author of a number of training manuals including: The Ultimate Bench Press Manual, Wilderness Basics, Strength training Secrets, Composite training and Power up your Driving Muscles. Danny has published articles in national and international magazines describing the benefits of living the healthy fitness lifestyle.

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