• Shambaugh P

• Back / physiology
• Electromyography
• Manipulation, Chiropractic
• Muscles / physiology

This study examines the effects of chiropractic adjustment on the muscles of the back. Vertebrae that are hypomobile may be held in that state by the erector spinae muscle group; adjusting such vertebrae should result in less muscle tension. By measuring the change in electrical activity, such relaxation can be observed. Hypomobile vertebrae were found by motion palpation. The patient was then placed prone and surface electrodes were placed over the upper trapezius, upper erector spinae (T3-T5), and lumbar erector spinae (L1-L3) muscle groups on both sides of the body. The patient was adjusted using full spine toggle recoil thrusts, and postadjustment readings were taken. Results from this study show that significant changes in muscle electrical activity occur as a consequence of adjusting. On average, a 25% reduction in muscle activity was observed across the 20 subjects tested, while no significant reductions were observed with the control group of 14 subjects. Significant reductions in side-to-side imbalances were also observed.

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