Acute Effect of Noradrenergic Modulation on Motor Output Adjustment in Men

Purpose To determine the role of noradrenergic modulation in the control of motor output, we compared the acute effect of reboxetine (REB), a noradrenaline reuptake inhibitor, to a placebo (PLA) on knee extensors motor performance and cortical and spinal excitability. Methods Eleven young men took part in two randomized experiments during which they received either 8 mg of REB or a PLA. The torque produced during a maximal voluntary contraction (MVC) and its variability (i.e., coefficient of variation) during submaximal contractions ranging from 5% to 50% MVC were measured. Paired electrical (PES) and transcranial magnetic stimulation (TMS) were used to assess changes in voluntary activation during MVC, and corticospinal (motor-evoked potential (MEP)) and spinal excitability (Hoffmann (H) reflex) during contraction at 20% MVC. Results MVC torque and torque steadiness increased respectively by 9.5% and 24% on average in REB compared with PLA condition (P

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