Original Articles
The influence of a chiropractic manipulation on lumbar kinematics and electromyography during simple and complex tasks: A case study,☆☆

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Abstract

Objective: To investigate whether a more sophisticated and detailed analysis of both simple and complex tasks may yield more information regarding the short-term influence of an adjustment on spine biomechanics. Methods: The study used a single-subject, before-after design. Three-dimensional spine kinematics and trunk muscle electromyography were assessed during a variety of tasks performed by a professional golfer exhibiting non-specific, chronic, low back pain. The patient received a right-to-left and left-to-right spinous pull adjustment. Results: After the adjustment, changes were seen in all 3 axes of motion during a golf swing, with concomitant muscle responses. In addition, changes in the off axes of motion were seen during simple movement tasks. Conclusions: A more detailed spine kinematic analysis, specifically analysis of motion in the nonprincipled axes, yielded more information regarding the short-term influence of an adjustment on lumbar spine motion and muscle function. (J Manipulative Physiol Ther 1999;22:576–81)

Introduction

Optimal treatment of spine problems with manipulation must be based on a solid understanding of the effects on biomechanics. Immediate changes in lateral flexion in the cervical spine have been reported in the literature; however, to our knowledge, no research has been reported on the immediate influence of manipulation on lumbar range of motion (ROM). A long-term study1 found no correlation, after manipulative therapy, in the long-term changes in sagittal flexion ROM and pain scores. Typically, assessment of an adjustment's influence on spinal electromyography (EMG) has focused on simple static tasks.2 By using such simple measures of movement kinematics (ie, one plane or about one axis only), one may overlook the possibility of effects on motion about the other 2 axes, which can provide information on the quality of motion. In this article two suggestions are proposed as ways to better elucidate the short-term influence of an adjustment on spinal motion: (1) the use of full 3-dimensional analysis of spine kinematics and (2) analysis of more complex motor control tasks (eg, golf swing) rather than simple tasks that comprise a clinical test.

Specifically, this study presents documentation of the influence of a manipulation on lumbar spine kinematics about all 3 axes (flexion-extension, lateral bend, and axial twist) while performing motions of forward flexion, lateral bend, and axial twist, as well as during a complex motor task (the golf swing) because it was possible that the effects of manipulation would not be manifested until a complex task was assessed, requiring a large amount of coupled motion, with additional integration of kinesthetic components. In addition, trunk muscle activity was assessed before and after manipulation during these tasks, as well as during quiet stance.

Section snippets

Subject characteristics

Our subject, a 31-year-old carded member of the Professional Golfer's Association with chronic low back pain, was assessed before and after receiving a chiropractic manipulation. The fact that the subject was a professional golfer is important because professional golfers spend years developing consistent, efficient, and repeatable kinematic profiles to their golf swing.

Tasks

The sequence of events was as follows:

  • 1.

    3 trials of full flexion;

  • 2.

    3 trials of right and left lateral bend;

  • 3.

    3 trials of right and

Peak ROM changes during simple tasks

The subject showed no changes in peak ROM during simple flexion or axial twist tasks. During right lateral bend, the subject increased his ROM by 1.26 degrees (before, 26.93 degrees [0.15]; after, 28.19 degrees [0.49]). During left lateral bend, the subject increased his ROM by 4.63 degrees (before, 23.27 degrees [1.42]; after, 27.91 degrees [0.49]).

Changes in off-axes ROM during simple movement tasks

Average left lateral bending movement during peak flexion decreased from 4.92 degrees to 0.89 degrees (Fig 1).

. Lumbar spine, lateral-bend ROM

Discussion

The aim of this article is to evaluate the potential of more sophisticated analysis approaches to better elucidate the effects of manipulation on spinal biomechanics.

This single case study proves that documenting just a single axis of motion, usually the sagittal plane, may overlook clinically significant changes after manipulation in a subject's lumbar kinematics. This is seen in the changes found in peak lateral-bend ROM. Furthermore, simply assessing motion in the primary plane of movement

Conclusion

It must be stressed that this is a single case study with few trials. This limits the ability to draw a causal link between an adjustment and the changes found in this study. The data simply imply a need to consider tasks other than the usual clinical tasks to evaluate the effects of manipulation. Future work should consider these tasks by using a more rigorous study design and increased number of subjects, together with the use of a sham manipulation control group. Despite the limitations of

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Submit reprint requests to: Stuart M. McGill, PhD, Professor, Faculty of Applied Health Sciences, Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.

☆☆

Supported by the Natural Sciences and Engineering Research Council and the Canadian Memorial Chiropractic College.

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