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Effect of posture and body weight loading on spinal posterior root reflex responses
Author(s) -
MegíaGarcía Álvaro,
SerranoMuñoz Diego,
CominoSuárez Natalia,
delAma Antonio J.,
Moreno Juan C.,
GilAgudo Angel,
Taylor Julian,
GómezSoriano Julio
Publication year - 2021
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.15448
Subject(s) - supine position , reflex , h reflex , stimulation , stimulus (psychology) , electromyography , medicine , body weight , anatomy , spinal cord , anesthesia , physical medicine and rehabilitation , psychology , psychiatry , psychotherapist
Abstract The posterior root muscle response (PRM) is a monosynaptic reflex that is evoked by single pulse transcutaneous spinal cord stimulation (tSCS). The main aim of this work was to analyse how body weight loading influences PRM reflex threshold measured from several lower limb muscles in healthy participants. PRM reflex responses were evoked with 1‐ms rectangular monophasic pulses applied at an interval of 6 s via a self‐adhesive electrode (9 × 5 cm) at the T11–T12 vertebral level. Surface electromyographic activity of lower limb muscles was recorded during four different conditions, one in decubitus supine (DS) and the other three involving standing at 100%, 50%, and 0% body weight loading (BW). PRM threshold intensity, peak‐to‐peak amplitude, and latency for each muscle were analysed in different conditions study. PRM reflex threshold increased with body weight unloading compared with DS, and the largest change was observed between DS and 0% BW for the proximal muscles and between DS and 50% BW for distal muscles. Peak‐to‐peak amplitude analysis showed only a significant mean decrease of 34.6% (SD 10.4, p = 0.028) in TA and 53.6% (SD 15.1, p = 0.019) in GM muscles between DS and 50% BW. No significant differences were observed for PRM latency. This study has shown that sensorimotor networks can be activated with tSCS in various conditions of body weight unloading. Higher stimulus intensities are necessary to evoke reflex response during standing at 50% body weight loading. These results have practical implications for gait rehabilitation training programmes that include body weight support.