Electromyographic Responses of Neck, Back, and Limb Outlet Muscles Associated With High-Velocity, Low-Amplitude Manual Cervical and Upper Thoracic Spinal Manipulation of Individuals With Mild Neck Disability: A Descriptive Observational Investigation.

OBJECTIVES: The purpose of this study was to investigate the extent of electromyographic responses associated with manual high-velocity, low-amplitude (HVLA) spinal manipulation systematically applied to the upper and lower cervical and upper thoracic spines in a cohort with mild neck disability. METHODS: The study was a descriptive observational investigation, with all participants receiving the same interventions. Nineteen participants with mild neck disability received 6 manual HVLA manipulations to the cervical and upper thoracic spine. Bipolar surface electromyography electrode pairs were used to measure responses of 16 neck, back, and limb outlet muscles bilaterally. The number of electromyographic responses was then calculated. RESULTS: Electromyographic responses associated with cervical and thoracic manipulation occurred in a median of 4 of the 16 (range: 1-14) recorded muscles. Cervical spinal manipulation was associated with the highest rates of electromyographic responses in neck muscles, whereas responses in back muscles were highest after upper thoracic manipulation. CONCLUSION: Cervical spinal manipulation was associated with the highest rate of electromyographic responses in muscles of the cervical spine (sternocleidomastoid and splenius cervicis), whereas responses in back muscles (upper and middle trapezius, latissimus dorsi, and longissimus thoracis) were highest after upper thoracic manipulations. This result suggests that electromyographic muscular responses associated with spinal manipulation primarily occur locally (close to the target segment) rather than distally.