The aim of the current study was to investigate, using a controlled, repeated measure design, the neurophysiological responses following an acute bout of muscle energy technique (MET). Transcranial magnetic stimulation elicited motor evoked potentials using a 110 mm double cone coil placed over the motor area of the brain, while Hoffman reflexes (H-reflex) were measured from the posterior tibial nerve using electrical stimulation. Responses were measured using surface electromyography electrodes placed over the lateral head of the gastrocnemius muscle in 12 asymptomatic volunteers. An MET aimed at the lumbosacral joint was performed bilaterally. Data were collected pre-intervention, after a control intervention, and after the MET intervention. A significant increase was found in evoked potential silent period (SP) duration (F2,22 = 7.64; p = 0.03) over time following MET, but not the control intervention. A significant decrease was found in H-reflex (F1.3,14.4 = 13.8; p = 0.01) over time following the MET intervention. MET applied to the lumbosacral joint produced a significant decrease in corticospinal and spinal reflex excitability, suggesting overall decreased motor excitability.