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Electromyographic characteristics at the onset of independent walking in infancy
1Department of Liberal Arts, Kansai Medical University, Osaka, Japan. okamoto@makino.kmu.ac.jp
Insights
Infant walking shows unique electromyographic patterns, including excessive muscle activity for stability and balance. These patterns mature as muscle strength and balance improve with age.
Area of Science:
- Developmental biomechanics
- Pediatric motor control
- Neuroscience
Background:
- Independent gait acquisition is a critical developmental milestone.
- Understanding the neuromuscular control of infant walking is essential for identifying developmental trajectories.
Purpose of the Study:
- To characterize the electromyographic (EMG) patterns during the early stages of independent infant walking.
- To longitudinally track changes in muscle activity from 10 months to 3 years of age.
Main Methods:
- Longitudinal recording of electromyograms (EMG) from leg muscles during walking.
- Analysis of muscle activation patterns during different gait phases (stance, swing).
Main Results:
- Infant gait exhibits distinct EMG characteristics compared to adult gait, particularly in the first month post-acquisition.
- Specific muscle activation patterns (vastus medialis, rectus femoris, biceps femoris, tibialis anterior, gastrocnemius) were observed for stability and center of mass control.
- Excessive muscle activity was noted, correlating with immature muscle strength and balance systems.
Conclusions:
- The observed electromyographic patterns reflect compensatory strategies for underdeveloped motor control in early walkers.
- Maturation of muscle strength and balance systems leads to a reduction in the excessive myoelectric activity seen in infant gait.
Abstract:
In order to elucidate electromyographic characteristics of infant walking at the onset of independent gait, we longitudinally recorded electromyograms from muscles of both legs during the learning process of walking in an infant, from ten months after birth until about three years of age. We found electromyographic characteristics of infant gait up to around one month after learning to walk that are not usually seen in adult gait. In stance phase from foot contact until push off, the role of the vastus medialis for maintaining stability became clear as a slightly squatted position was used to lower the center of gravity. Orderly reciprocal or cocontraction patterns of activity in the rectus femoris and biceps femoris or in the tibialis anterior and gastrocnemius were found to be related to returning the body's center of mass toward its initial position. In the latter half of swing phase, the vastus medialis and gastrocnemius showed strong activities with the knee extending and ankle plantarflexing for active leg extension to prevent falling. These characteristically excessive muscle activities in infant walking are considered to express weak muscle strength and an immature balancing system. As months and years pass, the muscles become stronger and balance matures, obviating the need for so much myoelectric activity.