title: Intracortical inhibition in the soleus muscle is reduced during the control of upright standing in both young and old adults.
abstract: OBJECTIVE
  In a previous study, we reported that a short-interval intracortical inhibition (SICI) decreases in old but not in young adults when standing on foam vs. a rigid surface. Here, we examined if such an age by task difficulty interaction in motor cortical excitability also occurs in easier standing tasks.
  
  
  METHODS
  Fourteen young (23 ± 2.7 years) and fourteen old (65 ± 4.1 years) adults received transcranial magnetic brain stimulation and peripheral nerve stimulation, while they stood with or without support on a force platform.
  
  
  RESULTS
  In the soleus, we found that SICI was lower in unsupported (35 % inhibition) vs. supported (50 %) standing (p = 0.007) but similar in young vs. old adults (p = 0.591). In the tibialis anterior, SICI was similar between conditions (p = 0.597) but lower in old (52 %) vs. young (72 %) adults (p = 0.030). Age and standing with or without support did not affect the Hoffmann reflex in the soleus.
  
  
  CONCLUSIONS
  The current data suggest that the motor cortex is involved in standing control, and that its role becomes more prominent with an increase in task difficulty.
authors.affiliation: Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands. selmapapegaaij@gmail.com.
authors.forename: Selma
authors.initials: S
authors.lastname: Papegaaij
authors.affiliation: Laboratory of Applied Biology, Faculty for Motor Sciences, Université Libre de Bruxelles, CP 640, route de Lennik 808, 1070, Brussels, Belgium.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Baudry
authors.affiliation: Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.|Department of Biomechanics, Faculty of Physical Education and Sport Sciences, Semmelweis University, Alkotás utca 44, Budapest, 1123, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Négyesi
authors.affiliation: Department of Medicine, University of Fribourg, Ch. du Musée 8, 1700, Fribourg, Switzerland.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Taube
authors.affiliation: Center for Human Movement Sciences, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.|Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK.
authors.forename: Tibor
authors.initials: T
authors.lastname: Hortobágyi
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006181:H-Reflex / Q000502:physiology; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D011187:Posture / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: Aging; Balance; Peripheral nerve stimulation; Short-interval intracortical inhibition; Transcranial magnetic stimulation