H-reflex and M-wave responses after voluntary and electrically evoked muscle cramping

Jan-Frieder Harmsen*, Christopher Latella, Ricardo Mesquita, Alessandro Fasse, Moritz Schumann, Michael Behringer, Janet Taylor, Kazunori Nosaka

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Purpose Despite the widespread occurrence of muscle cramps, their underlying neurophysiological mechanisms remain unknown. To better understand the etiology of muscle cramps, this study investigated acute effects of muscle cramping induced by maximal voluntary isometric contractions (MVIC) and neuromuscular electrical stimulation (NMES) on the amplitude of Hoffmann reflexes (H-reflex) and compound muscle action potentials (M-wave). Methods Healthy men (n = 14) and women (n = 3) participated in two identical sessions separated by 7 days. Calf muscle cramping was induced by performing MVIC of the plantar flexors in a prone position followed by 2.5-s NMES over the plantar flexors with increasing frequency and intensity. H-reflexes and M-waves evoked by tibial nerve stimulation in gastrocnemius medialis (GM) and soleus were recorded at baseline, and after MVIC-induced cramps and the NMES protocol. Results Six participants cramped after MVIC, and H-reflex amplitude decreased in GM and soleus in Session 1 (- 33 +/- 32%, - 34 +/- 33%, p = 0.031) with a similar trend in Session 2 (5 cramped, p = 0.063), whereas the maximum M-wave was unchanged. After NMES, 11 (Session 1) and 9 (Session 2) participants cramped. H-reflex and M-wave recruitment curves shifted to the left in both sessions and muscles after NMES independent of cramping (p

Original languageEnglish
Pages (from-to)659-672
Number of pages14
JournalEuropean Journal of Applied Physiology
Issue number2
Early online date27 Nov 2020
Publication statusPublished - Feb 2021


  • Maximal voluntary isometric contraction
  • Gastrocnemius medialis
  • Soleus
  • Neuromuscular electrical stimulation
  • Hoffmann reflex

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