title: Impact of Spinal Manipulation on Cortical Drive to Upper and Lower Limb Muscles.
abstract: This study investigates whether spinal manipulation leads to changes in motor control by measuring the recruitment pattern of motor units in both an upper and lower limb muscle and to see whether such changes may at least in part occur at the cortical level by recording movement related cortical potential (MRCP) amplitudes. In experiment one, transcranial magnetic stimulation input-output (TMS I/O) curves for an upper limb muscle (abductor pollicus brevis; APB) were recorded, along with F waves before and after either spinal manipulation or a control intervention for the same subjects on two different days. During two separate days, lower limb TMS I/O curves and MRCPs were recorded from tibialis anterior muscle (TA) pre and post spinal manipulation. Dependent measures were compared with repeated measures analysis of variance, withpset at 0.05. Spinal manipulation resulted in a 54.5% ± 93.1% increase in maximum motor evoked potential (MEPmax) for APB and a 44.6% ± 69.6% increase in MEPmax for TA. For the MRCP data following spinal manipulation there were significant difference for amplitude of early bereitschafts-potential (EBP), late bereitschafts potential (LBP) and also for peak negativity (PN). The results of this study show that spinal manipulation leads to changes in cortical excitability, as measured by significantly larger MEPmax for TMS induced input-output curves for both an upper and lower limb muscle, and with larger amplitudes of MRCP component post manipulation. No changes in spinal measures (i.e., F wave amplitudes or persistence) were observed, and no changes were shown following the control condition. These results are consistent with previous findings that have suggested increases in strength following spinal manipulation were due to descending cortical drive and could not be explained by changes at the level of the spinal cord. Spinal manipulation may therefore be indicated for the patients who have lost tonus of their muscle and/or are recovering from muscle degrading dysfunctions such as stroke or orthopaedic operations and/or may also be of interest to sports performers. These findings should be followed up in the relevant populations.
authors.affiliation: Centre for Chiropractic Research, New Zealand College of Chiropractic, Auckland 1060, New Zealand. Heidi.Haavik@nzchiro.co.nz.
authors.forename: Heidi
authors.initials: H
authors.lastname: Haavik
authors.affiliation: Centre for Chiropractic Research, New Zealand College of Chiropractic, Auckland 1060, New Zealand. imran.niazi@nzchiro.co.nz.|Centre for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg 9220, Denmark. imran.niazi@nzchiro.co.nz.
authors.forename: Imran Khan
authors.initials: IK
authors.lastname: Niazi
authors.affiliation: Centre for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg 9220, Denmark. mj@hst.aau.dk.
authors.forename: Mads
authors.initials: M
authors.lastname: Jochumsen
authors.affiliation: Chirofit (Private Practice), 32a Normanby Rd, Mt Eden Auckland, Auckland 1024, New Zealand. diane@chirofit.co.nz.
authors.forename: Diane
authors.initials: D
authors.lastname: Sherwin
authors.affiliation: Centre for Chiropractic Research, New Zealand College of Chiropractic, Auckland 1060, New Zealand. tadarida7@gmail.com.
authors.forename: Stanley
authors.initials: S
authors.lastname: Flavel
authors.affiliation: School of Medicine, Koç University, Rumelifeneri Yolu, Sariyer, Istanbul 34450, Turkey. kturker@ku.edu.tr.
authors.forename: Kemal S
authors.initials: KS
authors.lastname: Türker
keywords: movement related cortical potential; neural adaptations; transcranial magnetic stimulation