An Index of Gait Instability Based on Electromyographic Findings during the Development of Gait.

Abstract

To develop an index of gait instability from electromyographic information, we made observations on infants from the time they first began to walk independently at about one year of age until around three years of age. From our findings we obtained the following criteria. (1) Very unstable gait: As seen in a child within the first month of learning to walk the vastus medialis is active in the latter half of swing phase, the tibialis anterior and rectus femoris are active during stance phase, and activity of the vastus medialis is continuous. These electromyographic characteristics are not usually seen in subsequent childhood gait or in adult gait, and they serve as markers of very unstable gait. (2) Unstable gait: Activity of the gastrocnemius in the latter half of swing phase is generally noted only within the first three months after a child learns to walk, and that activity is interpreted as a sign of unstable gait. (3) Slightly unstable gait: Activity of the gastrocnemius in the first half of stance phase and continuous activities of the biceps femoris and gluteus maximus from initial contact with the floor until push off are found in children until three years of age. These activities are considered electromyographic markers of slightly unstable gait.

Application of an Electromyographic Index of Gait Instability to Developmental Process of Supported Walking in Normal Neonates and Infants.

“…We initially observed developmental process of supported walking in neonates and infants using an index of gait instability 5) . In interpreting the EMG pattern of supported walking in all subjects tested, we focused on the discharge pattern in the latter part of swing phase and in stance phase.…”

“…This is one of the more rhythmical walking-like patterns that we obtained in this neonate. The discharge patterns of leg muscles during newborn stepping are generally more irregular than in adult walking 3,5,10,11,15,19) .…”

“…Human gait without support is associated with muscle strength, balance, and postural control 1,2) . Although some people have to resort to supported walking by virtue of immaturity, aging, postoperative status, or disease, supported walking generally resembles the normal adult walking pattern except for the substitution of missing postural and balance elements with support [3][4][5][6][7] . However, to decide whether gait is stable or not is very difficult to evaluate from motion analysis alone, for example, by comparison with a normal pattern.…”

“…Okamoto et al 5) have determined signs of unstable walking from EMG activity patterns based on the developmental process of normal infant walking 3,[5][6][7][8][9] and normal adult walking 3,5,10,11) (Table 1), and have used them to analyze gait in terms of development processes and also as a way to electromyographically assess clinical process in gait training. They have reported that the vastus medialis is active in the latter half of swing phase, the tibialis anterior and rectus femoris are active during stance phase, and activity of the vastus medialis is continuous, as seen in a child within the first month of learning to walk.…”

“…Only a few attempts so far, however, have been made to study developmental changes of stepping by EMG, particularly in relation to gait instability. In this study, we applied the idea of the index of gait instability 5) to developmental changes during newborn stepping and infant supported walking.…”