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Electromyographic reflex responses to mechanical force, manually assisted spinal manipulative therapy
1Postdoctoral & Related Professional Education Department, Logan College of Chiropractic, St Louis, Missouri, USA. cjcolloca@neuromechanical.com
Spine
|June 20, 2001
Summary
Mechanical force, manually assisted spinal manipulative therapy (MFMA) consistently elicits neuromuscular reflex responses in patients with low back pain. These localized responses, measured via surface electromyography (sEMG), indicate a physiological mechanism for MFMA therapy.
Area of Science:
- Neuromuscular physiology
- Spinal biomechanics
- Musculoskeletal rehabilitation
Background:
- The physiological mechanisms underlying spinal manipulative therapy (SMT) for low back pain (LBP) remain incompletely understood.
- While SMT is known to elicit reflex responses in back muscles, their extent in LBP patients is not well-documented.
Purpose of the Study:
- To characterize and quantify electromyographic (EMG) reflex responses in paraspinal muscles during high-velocity, manually assisted SMT of the thoracolumbar spine and sacroiliac joints.
- To investigate the association between SMT application and EMG responses in patients with LBP.
Main Methods:
- Prospective clinical study involving 20 LBP patients undergoing localized, short-duration ( <5 msec) posteroanterior SMT thrusts.
- Surface EMG recordings (sEMG) were obtained from L5 and L3 erector spinae muscles, synchronized with force-time data.
- Analysis compared sEMG responses based on spinal level, contact point (spinous vs. transverse processes), and magnitude, defining positive responses based on established thresholds.
Main Results:
- Consistent, localized sEMG reflex responses were observed in paraspinal muscles following MFMA thrusts.
- Reflex response times averaged 2-4 msec, consistent with intraspinal conduction.
- 95% of patients exhibited positive sEMG responses, with thrusts on transverse processes yielding higher response rates (25.4%) than spinous processes (20.6%).
- Patients with more frequent LBP reported more pronounced sEMG responses.
Conclusions:
- This study provides the first evidence of neuromuscular reflex responses to MFMA spinal manipulative therapy in patients with low back pain.
- Mechanical stimulation of paraspinal muscles via transverse and spinous processes consistently produced localized sEMG responses.
- Understanding these neuromuscular characteristics may help elucidate the therapeutic benefits of SMT for musculoskeletal pain.