Lumbosacral Muscle Energy Technique produces immediate decreases in corticospinal and spinal reflex excitability in asymptomatic participants

Abstract

BackgroundLumbosacral HVLA has been reported to produce an immediate decrease in corticospinal and spinal reflex excitability, but muscle energy technique (MET), a commonly used technique involving voluntary isometric contraction, has not yet been explored. This study examined the effects of an application of MET to the lumbosacral joint on corticospinal excitability, as measured by motor evoked potentials (MEPs) using transcranial magnetic stimulation (TMS), and spinal reflex excitability, as measured by the Hoffman reflex (H-reflex). MethodsIn a controlled, repeated measure design, 12 asymptomatic volunteers (mean age = 26 ± 9.5 years; n = 5 males, n = 7 females) were measured for MEPs via TMS (10% above motor threshold) using a 110 mm double cone coil placed over the motor area of the brain, and H-reflexes from the tibial nerve using electrical stimulation, measured via surface electrodes over the gastrocnemius muscle. Data was collected at three time intervals: pre-intervention, following a control condition, and following the MET intervention. The MET intervention was performed bilaterally and engaged the rotation barrier at L5/S1 and used a light rotatory contraction force by the participant. Data for H-reflex and MEP amplitudes were normalised to the M-max amplitude, silent period (SP) duration was measured from the initial deflection of the MEP waveform until return of uninterrupted EMG and analysed using a one-way repeated measures ANOVA. ResultsA significant increase was found in evoked potential SP duration (F2,22 = 7.64; p = 0.03) over time. Post hoc analysis, with Bonferroni adjustment, revealed this significant change occurred following MET but not the control intervention, producing a medium effect size for MET (d = 0.52), but a small effect size for the control (d = 0.04). A significant change was found in H-reflex (F1.3,14.4 = 13.8; p = 0.01) over time, and post hoc analyses, with Bonferroni adjustment, showed that a decrease occurred after the MET intervention (p = 0.005). A medium effect size for MET was found (d = 0.59), whereas the effect following the control was small (d = 0.19). There were no significant changes in MEP/M-max ratio or MEP latency. ConclusionsAn application of MET applied to the lumbosacral joint produced a significant decrease in corticospinal and spinal reflex excitability, and no significant change occurred following the control intervention. The changes in SP duration and H-reflexes concur with previous results using HVLA, suggesting that both forms of manipulation may produce decreased motor excitability.