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Dynamic Chiropractic – July 16, 2005, Vol. 23, Issue 15

Trunk Strengthening

By Kim Christensen, DC, DACRB, CCSP, CSCS

A vitally important aspect of spinal health is the functional strength and coordination of the trunk support musculature. Since doctors of chiropractic deal with patients suffering from back pain, and also want to help people prevent back problems, we must be able to provide exercise guidance and recommendations to improve trunk strength.

The best exercises for a specific patient are those that will be rapidly effective, are easy to learn and perform, and are safe (they don't worsen the current condition or aggravate other problems). The exercises should also help the patient regain normal alignment and easy, natural movement. And the end result should lessen the chances of similar, recurring problems. While decreased flexibility is a problem for some patients, most studies have found that what the lumbar spine needs is improved muscular and structural support, in order to withstand the rigors of daily life.1 Strengthening has been found to be the most necessary component of lumbar spine rehabilitation in our primarily sedentary society.2 But which type of trunk strengthening exercise is best? Here are several considerations:

Central Stabilizers

Specific exercises must develop "dynamic control of lumbar spine forces in order to eliminate repetitive injury to the intervertebral discs, facet joints, and related structures."1 Determining which exercises to recommend is not easy, as some research supports the need for abdominal strengthening (including the transverse abdominus), others advise pelvic tilts, and still others focus on the importance of strengthening the lumbar extensor muscles, including the multifidus lumborum. The bottom line is that patients' needs vary, and the exercises that worked for one may not necessarily work for the next. The solution is to use clinical testing, and in particular, postural evaluation, including functional testing, to identify the most appropriate and effective trunk-strengthening exercise routine.

Harrison's "mirror image" concept of postural examination and rehabilitation is an accurate and very easy method of determining which primary exercise is important to consider. By evaluating each patient's three-dimensional posture and noting any specific deviations from the ideal intrinsic equilibrium, the doctor is able to identify the sources of excessive biomechanical stress and recommend specific corrective trunk-strengthening exercises. If a patient stands with the spine tilted to the right, it means there is a structural imbalance that needs to be retrained, by strengthening the muscle groups that pull the spine to the left. This is the simple concept that underlies the "mirror image" approach to determining trunk strengthening exercises, as well as functional deficits.

Closed Kinetic Chain

Weaker or injured muscles can be quickly strengthened with the use of resistance, to stimulate increases in strength by increasing the "neural drive." Resistance can come from a machine, from weights, from elastic tubing, or by just using the weight of the body.

Open-chain exercises for the spine are done non-weight-bearing, either lying on the ground or immersed in water (which removes much of the effect of gravity). Since the spine is part of a closed kinetic chain when it is bearing weight during daily and sports activities, it requires the co-contraction of accessory and stabilizing muscles. Closed-chain exercising brings neck and back rehab closer to real-life positions, and explains why patients make more rapid progress when they are taught to exercise in a functional (upright) position. The stabilizing muscles, the co-contractors, and the antagonist muscles all have to coordinate with the major movers during trunk strengthening exercises performed in a closed kinetic chain.

Proprioception and Balance

For many patients, and especially athletes, an additional goal of low back rehab is to regain the fine neurological control necessary for accurate spinal and full-body performance. This means that about five to 10 minutes of each workout should be spent exercising while standing on one leg with the eyes closed, while standing on a mini-tramp, or using a rocker board. The advantage of these balance exercises is seen when patients return to sports activities and can perform at high levels without having to consciously protect their backs. Back exercises done on a rocker board or while standing on one leg may be more useful than those done on a gym ball, since the entire body is in a closed-chain position during the exercises.

Prevention/Wellness

Long-term lumbosacral stability is a combination of balanced strength, sufficient flexibility and joint mobility, and good structural alignment. A regular exercise program with attention to the spinal extensor and gluteal muscles is important. Maintaining proper weight and general physical fitness can be of great help. Reducing the peaks of stress to the region is also helpful, especially during aging.

If there is substantial degeneration of the lower lumbar discs, shock-absorbing orthotics may be helpful. The effects of structural imbalances, such as leg-length difference, pelvic unleveling, increased sacral base angle, and spondylolisthesis, must be recognized and may require management. For example, excessive pronation at the foot and ankle is very common, and is frequently associated with chronic pelvic and low back symptoms;3 stabilizing orthotics are helpful for resolution. Investigators have found that "alteration of normal foot mechanics can adversely influence the normal functions of the ankle, knee, hip, and even the back."4

When a comprehensive treatment program includes adjustments, structural support, and rehabilitation, patients will be better prepared to maintain their spinal health, and they will have a deeper, more personal understanding of chiropractic philosophy. They will have experienced the power of their own bodies to heal and regain health, and they will be empowered to keep them at a higher level of fitness and function.

References

  1. Mayer TG, Smith SS, Keeley J, Mooney V. Quantification of lumbar function. Spine 1985;10:765-772.
  2. Mooney V, Gulick J, et al. Relationships between myoelectric activity, strength, and MRI of lumbar extensor muscles in back pain patients and normal subjects. J Spinal Dis 1997;10:348-356.
  3. Rothbart BA, Estabrook L. Excessive pronation: a major biomechanical determinant in the development of chondromalacia and pelvic lists. J Manip Physiol Therap 1988;11:373-379.
  4. Katoh Y et al. Biomechanical analysis of foot function during gait and clinical applications. Clin Orthop Rel Res 1983;177:23-33.

Kim Christensen, DC, DACRB, CCSP, CSCS
Director, Chiropractic Rehabilitation and Wellness Program
PeaceHealth Hospital
Longview, Washington



Click here for previous articles by Kim Christensen, DC, DACRB, CCSP, CSCS.

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