Post-activation depression of primary afferents reevaluated in humans

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Özyurt M. G., Topkara B., Şenocak B. S., Budan A. S., Yüce M. N., Türker K. S.

Journal of Electromyography and Kinesiology, vol.54, 2020 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 54
  • Publication Date: 2020
  • Doi Number: 10.1016/j.jelekin.2020.102460
  • Journal Name: Journal of Electromyography and Kinesiology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, CINAHL, EMBASE, MEDLINE, SportDiscus
  • Keywords: Electrical stimulation, Electromyogram, H-reflex, Motor control, Soleus muscle
  • Istanbul Gelisim University Affiliated: No

Abstract

Amplitude variation of Hoffmann Reflex (H-reflex) was used as a tool to investigate many neuronal networks. However, H-reflex itself is a subject to intrinsic changes including post-activation depression (P-AD). We aimed to investigate P-AD and its implication on motor control in humans. Upon tibial nerve stimulation in 23 healthy participants, peak-to-peak amplitude change of H-reflex was investigated using surface electromyography (SEMG) of soleus muscle. Variety of stimulus intensities, interstimulus intervals (ISIs), voluntary contraction levels/types and force recording were used to investigate the nature of P-AD. We have shown that P-AD was significantly stronger in the shorter ISIs. The only exception was the ISI of 200 msecs which had a weaker P-AD than some of the longer ISIs. Sudden muscle relaxation, on the other hand, further increased the effectiveness of the ongoing P-AD. Moreover, P-AD displayed its full effect with the first stimulus when there was no muscle contraction and was efficient to reduce the muscle force output by about 30%. These findings provide insight about the variations and mechanism of P-AD and could lead to improvements in diagnostic tools in neurological diseases.