title: Altered corticospinal transmission to the hand after maximum voluntary efforts.
abstract: BACKGROUND
  After maximal voluntary contractions (MVCs), responses to corticospinal tract stimulation change differently in arm and leg muscles. This study we examined responses in the first dorsal interosseous muscle (FDI).
  
  
  METHODS
  Stimulation of the corticospinal tract at the cervicomedullary motor evoked potentials in FDI. Stimuli were delivered before and after 10-s and 1-min MVCs. The reproducibility of changes in the cervicomedullary motor evoked potentials (CMEPs) was investigated. F-waves tested motoneuron excitability.
  
  
  RESULTS
  After the MVCs, the CMEP area was initially variable. By ~1 min after 10-s and 1-min MVCs, CMEPs in relaxed muscle decreased to 63 ± 15% and 52 ± 32%, respectively, of control and remained depressed for ~10 min. Responses evoked 2 days apart varied between subjects but not between days. After 10-s MVCs, F-waves were reduced at rest. During weak contraction, CMEPs but not F-waves were depressed.
  
  
  CONCLUSIONS
  Our results suggest that contraction produces changes at the corticomotoneuronal synapses to FDI. In addition, motoneuron excitability is reduced.
authors.affiliation: Neuroscience Research Australia and the University of New South Wales, Barker Street, Randwick, Sydney, New South Wales 2031, Australia.
authors.forename: Sabine
authors.initials: S
authors.lastname: Giesebrecht
authors.forename: Peter G
authors.initials: PG
authors.lastname: Martin
authors.forename: Simon C
authors.initials: SC
authors.lastname: Gandevia
authors.forename: Janet L
authors.initials: JL
authors.lastname: Taylor
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand / Q000294:innervation* / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D011712:Pyramidal Tracts / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D055815:Young Adult