title: H-reflex modulation in the human medial and lateral gastrocnemii during standing and walking.
abstract: BACKGROUND
  The soleus H-reflex is dynamically modulated during walking. However, modulation of the gastrocnemii H-reflexes has not been studied systematically.
  
  
  METHODS
  The medial and lateral gastrocnemii (MG and LG) and soleus H-reflexes were measured during standing and walking in humans.
  
  
  RESULTS
  Maximum H-reflex amplitude was significantly smaller in MG (mean 1.1 mV) or LG (1.1 mV) than in soleus (3.3 mV). Despite these size differences, the reflex amplitudes of the three muscles were positively correlated. The MG and LG H-reflexes were phase- and task-dependently modulated in ways similar to the soleus H-reflex.
  
  
  CONCLUSIONS
  Although there are anatomical and physiological differences between the soleus and gastrocnemii muscles, the reflexes of the three muscles are similarly modulated during walking and between standing and walking. Our findings support the hypothesis that these reflexes are synergistically modulated during walking to facilitate ongoing movement.
authors.affiliation: Program in Human Movement Science, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Makihara
authors.forename: Richard L
authors.initials: RL
authors.lastname: Segal
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Wolpaw
authors.forename: Aiko K
authors.initials: AK
authors.lastname: Thompson
mesh_terms: D000328:Adult; D001703:Biophysics; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography; D005260:Female; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D011187:Posture / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult