J. Donald Dishman, Douglas S. Greco and Jeanmarie R. Burke
The purpose of this study was to determine if high-velocity, low-amplitude spinal manipulation (SM) altered the effects of corticospinal excitability on motoneuron activity innervating the paraspinal muscles. The transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEPs) were recorded from relaxed lumbar erector spinae muscles of 72 asymptomatic subjects. The MEP amplitudes were evaluated pre-SM and post-SM or conditions involving prethrust positioning and joint loading or control. There was a transient increase in MEP amplitudes from the paraspinal muscles as a consequence of lumbar SM without concomitant changes after prethrust positioning and joint loading or in control subjects.
There is a postsynaptic facilitation of motoneurons and/or corticomotoneurons innervating paraspinal muscles as a consequence of SM. It appears that SM may offer unique sensory input to the excitability of the motor system as compared to prethrust positioning and joint loading and control conditions.
Journal of Manipulative and Physiological Therapeutics, 2008, 31(4),258-270