title: Eight weeks of local vibration training increases dorsiflexor muscle cortical voluntary activation.
abstract: The aim of this study was to evaluate the effects of an 8-wk local vibration training (LVT) program on functional and corticospinal properties of dorsiflexor muscles. Forty-four young subjects were allocated to a training (VIB,n= 22) or control (CON,n=22) group. The VIB group performed twenty-four 1-h sessions (3 sessions/wk) of 100-Hz vibration applied to the right tibialis anterior. Both legs were tested in each group before training (PRE), after 4 (MID) and 8 (POST) wk of training, and 2 wk after training (POST2W). Maximal voluntary contraction (MVC) torque was assessed, and transcranial magnetic stimulation (TMS) was used to evaluate cortical voluntary activation (VATMS), motor evoked potential (MEP), cortical silent period (CSP), and input-output curve parameters. MVC was significantly increased for VIB at MID for right and left legs [+7.4% (P= 0.001) and +6.2% (P< 0.01), respectively] and remained significantly greater than PRE at POST [+12.0% (P< 0.001) and +10.1% (P< 0.001), respectively]. VATMSwas significantly increased for right and left legs at MID [+4.4% (P< 0.01) and +4.7% (P< 0.01), respectively] and at POST [+4.9% (P= 0.001) and +6.2% (P= 0.001), respectively]. These parameters remained enhanced in both legs at POST2WMEP and CSP recorded during MVC and input-output curve parameters did not change at any time point for either leg. Despite no changes in excitability or inhibition being observed, LVT seems to be a promising method to improve strength through an increase of maximal voluntary activation, i.e., neural adaptations. Local vibration may thus be further considered for clinical or aging populations.NEW & NOTEWORTHYThe effects of a local vibration training program on cortical voluntary activation measured with transcranial magnetic stimulation were assessed for the first time in dorsiflexors, a functionally important muscle group. We observed that training increased maximal voluntary strength likely because of the strong and repeated activation of Ia spindle afferents during vibration training that led to changes in the cortico-motoneuronal pathway, as demonstrated by the increase in cortical voluntary activation.
authors.affiliation: Laboratoire Interuniversitaire de Biologie de la Motricité, Université de Lyon, Université Jean Monnet Saint-Etienne, Saint-Etienne, France.
authors.forename: Robin
authors.initials: R
authors.lastname: Souron
authors.affiliation: Laboratoire Interuniversitaire de Biologie de la Motricité, Université de Lyon, Université Jean Monnet Saint-Etienne, Saint-Etienne, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Farabet
authors.affiliation: Laboratoire Interuniversitaire de Biologie de la Motricité, Université de Lyon, Université Jean Monnet Saint-Etienne, Saint-Etienne, France.|Myology Unit, Referent Center of Rare Neuromuscular Diseases, Centre Hospitalier Universitaire Saint-Etienne, France; and.
authors.forename: Léonard
authors.initials: L
authors.lastname: Féasson
authors.affiliation: Laboratoire Interuniversitaire de Biologie de la Motricité, Université de Lyon, Université Jean Monnet Saint-Etienne, Saint-Etienne, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Belli
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Guillaume Y
authors.identifier: http://orcid.org/0000-0002-6395-0762
authors.initials: GY
authors.lastname: Millet
authors.affiliation: Laboratoire Interuniversitaire de Biologie de la Motricité, Université de Lyon, Université Jean Monnet Saint-Etienne, Saint-Etienne, France; thomas.lapole@univ-st-etienne.fr.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lapole
mesh_terms: D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011897:Random Allocation; D055070:Resistance Training / Q000379:methods* / Q000639:trends; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods / Q000639:trends; D014732:Vibration; D055815:Young Adult
keywords: Boltzmann modeling; cortical voluntary activation; corticospinal excitability and inhibition; local vibration; transcranial magnetic stimulation