筋電図からみた歩行開始期の特徴
岡本 勉 岡本 香代子
Electromyographic characteristics of infant walking at the onset of independent walking
Tsutomu OKAMOTO and Kayoko OKAMOTO
To determine the detailed electromyographic characteristics of infant walking at the onset of independent walking, we electromyographically studied the process of learning to walk in an infant who began walking for the first time on the 306 th day after birth . We examined the functional mechanisms of the leg muscles from the first day of walking until about 3 months after learning to walk.
1) Among the knee and hip joint muscles (the VM, the RF, and the BF) in the stance phase, the VM showed activity associated with holding a slightly flexed knee joint. A reciprocal pattern between the RF and the BF muscles came into play as the body inclined forward and backward, whereas a co contraction pattern of both muscles appeared when the body was erect. A reciprocal pattern between the TA and the LG helped to maintain balance to prevent falling forward or backward. Co-contraction patterns of these two muscles were seen to stabilize the ankle joint to maintain body balance. In the latter half of the swing phase, the VM and the LG showed strong activities with the knee extending and the ankle plantarflexing to prevent falling.
2) The discharge patterns during infant walking at the onset of independent walking were different from those of child and adult walking. The peculiar and strong discharges of infant walking at the onset of independent walking began to decrease or disappear about 1 month after learning to walk. Therefore, the discharge patterns observed until about 1 month after learning to walk may be considered discharge patterns peculiar to infant walking.
1歳頃の乳児が生後はじめて支持なしでひとり歩行を獲得することは、ヒトの移動運動の中では劇的で画期的な出来事である。
著者らは、1969年以来、歩行の習得･習熟過程を縦断的･横断的に動作筋電図記録してきた5〜9,14)。その結果、動作からは、McGraw4)、Bur-nett2)らも指摘しているように、独立歩行習得初期は上肢を外軽挙上し、接床期の間、歩隔(base)
関西医科大学 Kansai Medical University
