We tested whether a preceding muscle contraction changes reciprocal inhibition (RI) between forearm antagonists. Ri was studied in 14 healthy subjects by assessing changes in the H reflex (evoked by median-nerve stimulation) in forearm flexor muscles after conditioning radial-nerve stimulation at 0- and 20-ms intervals. The maximum sizes of the M wave (M-max) and H reflex (H-max) were also measured. After a long-lasting maximum voluntary handgrip contraction (mean rt SEM: 3.9 +/- 0.6 min) of ipsilateral forearm muscles, M-max and H-max were unchanged but RI was diminished. After contraction of the contralateral homologous muscles and after contraction elicited by ipsilateral muscle stimulation, RI remained unchanged. These results show that a preceding maximum voluntary contraction (lasting 30 s or more) reduces the activity of the spinal inhibitory interneurons mediating Ri. This finding may imply the need to reinterpret results from RI studies in normal subjects and in patients with movement disorders. (C) 2000 John Wiley & Sons, Inc.
|Titolo:||Postcontraction depression of reciprocal inhibition in human forearm muscles|
|Parole Chiave:||H reflex; Muscle contraction; Muscle fatigue; Postcontraction effects; Reciprocal inhibition; Spinal inhibitory interneurons|
|Settore Scientifico Disciplinare:||Settore MED/26 - Neurologia|
|Data di pubblicazione:||2000|
|Digital Object Identifier (DOI):||10.1002/1097-4598(200009)23:9<1335::AID-MUS3>3.0.CO;2-G|
|Appare nelle tipologie:||01 - Articolo su periodico|