The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and directly stimulating the afferent nerve. Studying H-reflex modulation provides insight into how the nervous system centrally modulates stretch reflex responses.A common measure of H-reflex gain is the slope of the relationship between H-reflex amplitude and EMG amplitude. To examine soleus H-reflex gain across a range of EMG levels during human locomotion, we used simulated reduced gravity to reduce muscle activity. We hypothesised that H-reflex gain would be independent of gravity level.We recorded EMG from eight subjects walking (1.25 m s-1) and running (3.0 m s-1) at four gravity levels (1.0, 0.75, 0.5 and 0.25 G (Earth gravity)). We normalised the stimulus M-wave and resulting H-reflex to the maximal M-wave amplitude (Mmax) elicited throughout the stride to correct for movement of stimulus and recording electrodes relative to nerve and muscle fibres. Peak soleus EMG amplitude decreased by ~30% for walking and for running over the fourfold change in gravity. As hypothesised, slopes of linear regressions fitted to H-reflex versus EMG data were independent of gravity for walking and running (ANOVA, P > 0.8). The slopes were also independent of gait (P > 0.6), contrary to previous studies. Walking had a greater y-intercept (19.9% Mmax) than running (-2.5% Mmax; P < 0.001). At all levels of EMG, walking H-reflex amplitudes were higher than running H-reflex amplitudes by a constant amount. We conclude that the nervous system adjusts H-reflex threshold but not H-reflex gain between walking and running. These findings provide insight into potential neural mechanisms responsible for spinal modulation of the stretch reflex during human locomotion.\n<\/p>\n","protected":false},"excerpt":{"rendered":"
The Hoffmann (H-) reflex is an electrical analogue of the monosynaptic stretch reflex, elicited by bypassing the muscle spindle and<\/p>\n","protected":false},"author":22,"parent":0,"menu_order":0,"template":"","format":"standard","meta":{"_acf_changed":false},"tags":[],"thema":[5870,5866],"produktgruppe":[5827],"literatur_kategorie":[7213],"class_list":["post-162378","literatur","type-literatur","status-publish","format-standard","hentry","thema-basics","thema-diagnostics-using-leonardo-pqct","produktgruppe-leonardo-en","literatur_kategorie-scientific-publications"],"acf":[],"_links":{"self":[{"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/literatur\/162378","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/literatur"}],"about":[{"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/types\/literatur"}],"author":[{"embeddable":true,"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/users\/22"}],"version-history":[{"count":0,"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/literatur\/162378\/revisions"}],"wp:attachment":[{"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/media?parent=162378"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/tags?post=162378"},{"taxonomy":"thema","embeddable":true,"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/thema?post=162378"},{"taxonomy":"produktgruppe","embeddable":true,"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/produktgruppe?post=162378"},{"taxonomy":"literatur_kategorie","embeddable":true,"href":"https:\/\/stratec-med.com\/en\/wp-json\/wp\/v2\/literatur_kategorie?post=162378"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}