Soleus and lateral gastrocnemius H-reflexes during standing with unstable footwear

Abstract : Introduction: Unstable footwear has been shown to increase lower extremity muscle activity, but the reflex response to perturbations induced by this intervention is unknown. Methods: Twenty healthy subjects stood in stable and unstable footwear conditions (presented randomly) while H-reflex amplitude and background muscle activity were measured in the soleus and lateral gastrocnemius (LG) muscles. Results: Wearing unstable footwear resulted in larger H-reflexes (normalized to the maximal M-wave) for the LG (+12%; P=0.025), but not for the soleus (+4%; P>0.05). Background activity of both muscles was significantly higher in the unstable condition. Conclusions: The H-reflex facilitation observed with unstable footwear was unexpected, as challenging postural conditions usually result in reflex depression. Increased muscle activity, decreased presynaptic inhibition, and/or more forward postural position may have (over-)compensated the expected reflex depression. Differences between LG and soleus H-reflex modulation may be due to diverging motor unit recruitment thresholds.
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https://hal-univ-bourgogne.archives-ouvertes.fr/hal-01302868
Contributeur : Caps - Université de Bourgogne <>
Soumis le : vendredi 15 avril 2016 - 12:20:20
Dernière modification le : vendredi 8 juin 2018 - 14:50:17

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Bernd Friesenbichler, Romuald Lepers, Nicola A. Maffiuletti. Soleus and lateral gastrocnemius H-reflexes during standing with unstable footwear. Muscle & nerve. Supplement., 2015, 51 (5), pp.764-766. ⟨10.1002/mus.24601⟩. ⟨hal-01302868⟩

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