Enhanced stretch reflex excitability in the soleus muscle during passive standing posture in humans

Sachio Shimba, Noritaka Kawashima, Yuji Ohta, Shin Ichiroh Yamamoto, Kimitaka Nakazawa

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The purpose of this study was to test whether the spinal reflex excitability of the soleus muscle is modulated as posture changes from a supine to a passive upright position. Eight healthy subjects (29.6±5.4 yrs) participated in this study. Stretch and H-reflex responses were elicited while the subjects maintained passive standing (ST) and supine (SP) postures. The passive standing posture was accomplished by using a gait orthosis to which a custom-made device was mounted to elicit stretch reflex in the soleus muscle. This orthosis makes it possible to elicit stretch and H-reflexes without background muscle activity in the soleus muscle. The results revealed that the H-reflex amplitude in the ST was smaller than that in the SP condition, which is in good agreement with previous reports. On the other hand, the stretch reflex was significantly larger in the ST than in the SP condition. Since the experimental conditions of both the stretch and H-reflex measurements were exactly the same, the results were attributed to differences in the underlying neural mechanisms of the two reflex systems: different sensitivity of the presynaptic inhibition onto the spinal motoneuron pool and/or a change in the muscle spindle sensitivity.

Original languageEnglish
Pages (from-to)406-412
Number of pages7
JournalJournal of Electromyography and Kinesiology
Issue number3
Publication statusPublished - 2010 Jun 1


  • H-reflex
  • Posture
  • Stretch reflex
  • Task-dependent modulation
  • Upright standing

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Biophysics
  • Clinical Neurology


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