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Soleus and lateral gastrocnemius H‐reflexes during standing with unstable footwear
Author(s) -
Friesenbichler Bernd,
Lepers Romuald,
Maffiuletti Nicola A.
Publication year - 2015
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.24601
Subject(s) - h reflex , reflex , soleus muscle , physical medicine and rehabilitation , motor unit , facilitation , stretch reflex , medicine , electromyography , anatomy , gastrocnemius muscle , anesthesia , psychology , neuroscience , skeletal muscle
: 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. Muscle Nerve 51 :764–766, 2015