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Core Training: Considering Anatomy and Function in Spinal Flexion Exercises ~ Johann Windt

Up to eighty-five percent of the population will experience low back pain at some point during their lives.(1) In response to this potentially debilitating condition, the link between low back pain and core training has long been investigated. Numerous investigations have demonstrated that various core training regimes may help mitigate chronic low back pain.(2-4)

Optimal core training in the treatment of lower back pain is beyond the scope of this post, and has been written of elsewhere.(5) Instead, this post will serve as a brief reminder to consider a couple concerns associated with repeated spinal flexion exercises (ie. sit-ups and crunches) in core training and low back rehabilitation before encouraging or prescribing them.

Photo by The U.S. Army. Used with permission. All rights reserved. Source: flickr

Photo by The U.S. Army. Used with permission. All rights reserved. Source: flickr

Many people still consider spinal flexion exercises as a primary mode of core training. Dr. Stuart McGill, in particular, has highlighted two primary concerns with these exercises, especially if done for treatment or prevention of low back pain. One concern is anatomical, another functional.

First, data has demonstrated that unlike spinal compression, repeated spinal flexion consistently contributes to the deterioration of the intervertebral discs and increases the risk for disc herniation.(6-7) Furthermore, the execution of full sit-ups exacerbates this problem by placing a large compressive load in the lumbar spine in its flexed position.(8-9)

From a functional perspective, such exercises emphasize the production of power from abdominal muscles initiating the movement. However, in the majority of everyday situations and in most sporting instances, the core musculature is braced and transmits the force produced by the hips and legs.(10-11)

For both these reasons, it may be wise to replace exercises that emphasize spinal flexion with those whereby the core resists motion through the bracing of the abdomen.(12) Variations of the crunch, such as the curl-up, help to recruit the rectus abdominis adequately while sparing the lumbar spine.(11-12)

This is not a call to completely abandon spinal flexion exercises, but simply a reminder of one component of making wise, evidence-based decisions regarding core training for low back pain. Given the popularity of these exercises, understanding the above concerns can help inform practice and improve patient outcomes.

For more information on core-training and its role in injury prevention, rehabilitation and performance read Chapter 14 “Core Stability” and Chapter 26, “Low Back Pain” in Clinical Sports Medicine.

Johann Windt is a graduate student at the University of British Columbia under the supervision of Dr. Karim Khan. Windt’s experience as a strength and conditioning coach and trainer empowers his belief that exercise is medicine, the message that his current research promotes.

References:

1      Press J, Dvorak J. Low back pain. In Brukner P, Bahr R, Blair S, et al. eds. Brukner & Khan’s Clinical Sports Medicine. McGraw Hill 2012. 463–91.

2      Saal JS, Saal JA, Yurth EF. Nonoperative Management of Herniated Cervical Intervertebral Disc With Radiculopathy. Spine 1996;21:1877–83.

3      Manniche C, Lundberg E, Christensen I, et al. Intensive dynamic back exercises for chronic low back pain: a clinical trial. Pain 1991;47:53–63.

4      O’Sullivan PB, Phyty NDM, Twomey LT, et al. Evaluation of Specific Stabilizing Exercise in the Treatment of Chronic Low Back Pain With Radiologic Diagnosis of Spondylolysis or Spondylolisthesis. Spine 1997;22:2959–67.

5      McGill S. Low back disorders: evidenced-based prevention and rehabilitation. 2nd ed. Champaign, IL: : Human Kinetics 2007.

6      Callaghan JP, McGill SM. Intervertebral disc herniation: studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force. Clin Biomech 2001;16:28–37.

7      Tampier C, Drake JDM, Callaghan JP, et al. Progressive Disc Herniation. Spine 2007;32:2869–74.

8      McGill SM. The mechanics of torso flexion: situps and standing dynamic flexion manoeuvres. Clin Biomech 1995;10:184–92.

9      Juker D, McGill SM, Kropf P, et al. Quantitative intramuscular myoelectric activity of lumbar portions of psoas and the abdominal wall during a wide variety of tasks. Med Amp Sci Sports Amp Exerc 1998;30:301–10.

10   McGill S. Core Training: Evidence Translating to Better Performance and Injury Prevention. Strength Cond J 2010;32.

11   McGill S. Ultimate back fitness and performance. Backfitpro Inc 2009.

12   McGill SM. Low Back Exercises: Evidence for Improving Exercise Regimens. Phys Ther 1998;78:754–65.

 

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