Treatment and Response Factors in Muscle Activation during Spinal Manipulation.

Area of Science:

• Neuromuscular responses
• Spinal manipulation
• Paraspinal muscles

Background:

• Spinal manipulation elicits neuromuscular responses in paraspinal muscles.
• Understanding factors influencing these responses offers clinical insights.

Purpose of the Study:

• To quantify the impact of treatment factors (manipulation sequence, site) and response factors (muscle layer, location, side) on neuromuscular response to spinal manipulation.
• To analyze muscle activity onset delays and response counts.

Main Methods:

• Surface and indwelling electromyography recorded from 8 muscle sites during lumbar side-lying manipulations.
• 20 asymptomatic participants were studied.
• Mixed-model linear regressions, effect sizes, and equivalence testing were used for analysis.

Main Results:

• Treatment factors (sequence, L3 vs. SI site) showed no significant differences in response count or onset delay.
• Deeper multifidi muscles had shorter onset delays than superficial muscles.
• Left-sided muscles exhibited more responses and shorter onset delays compared to the right.
• Response rate decreased and onset delay increased with distance from the manipulation site.

Conclusions:

• Manipulation site specificity may not be crucial for lumbar spinal manipulation's neuromuscular response.
• Performing multiple manipulations in adjacent areas (L3, S1) does not significantly alter responses.
• Muscle response rate is higher and onset delay is shorter closer to the manipulation site.