摘要：The disorder level in standing posture of the aged was evaluated by the disappearance period of electric discharge in musculus gastrocnemius(Silent Period). Subjects were nine aged people and ten healthy young people . They were ordered to stand in the upright position on both flat floor and forwardly sloped plate by 20 degrees with a vibrators fastened on both tendon achilles. Vibration at the frequency of 70 Herz was appliedfor one minutes, and tibial nerve was stimulated with the supramaximal electrical stimulation at 0.2 Herz of frequency.1) Under the resting condition, silent period of the aged was 24.0ms on flat floor and 10.8ms on sloped plate longer than those of young people.2) Both aged and young people showed longer silent period during receiving vibration than under the resting condition.Prolongation of silent period which implies lowered excitability of α motorneurons at the cornua anterius of spinal cord at the upright position suggested that the upper central nervous systems might control greatly outside stimulation on proprioceptors.
关键词：silent period; control system in standing posture; vibratory reflex
