Changes in the excitability of the H-reflex in wrist flexors related to the prone or supine position of the forearm in man.
The effect of the forearm position, prone vs. supine, on the excitability of the H-reflex in flexor carpi radialis (FCR) muscle was tested in nine adult volunteers by comparing the recruitment profiles of the H and M waves. The H-reflex size, normalized to the maximal M response, was lower when the forearm was supine than when it was prone, with an average reduction of about 50% over most of the H-recruitment curve. In three wrist positions, intermediate between prone and supine, the amount of reflex attenuation was related to the prono-supination angle. Control experiments excluded that the changes in the H reflex excitability were due to displacements of the stimulating or recording electrodes.
Baldissera
F
F
Istituto di Fisiologia Umana II, Università degli Studi di Milano, Via Mangiagalli 32, 20113, Milan, Italy. fausto.baldissera@unimi.it
Bellani
G
G
Cavallari
P
P
Lalli
S
S
D000328:Adult; D004576:Electromyography / Q000706:statistics & numerical data; D005260:Female; D005542:Forearm / Q000033:anatomy & histology / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000033:anatomy & histology / Q000502:physiology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000294:innervation / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D016684:Prone Position / Q000502:physiology; D012399:Rotation; D016683:Supine Position / Q000502:physiology; D014953:Wrist / Q000033:anatomy & histology / Q000502:physiology*