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Updated: Aug 6, 2026
Experimental Methods to Study Human Postural Control
Published on: September 11, 2019
Developmental changes in compensatory responses to unexpected resistance of leg lift during gait initiation
Marjorie Woollacott1, Christine Assaiante
1Department of Exercise and Movement Science, University of Oregon, Eugene, OR 97403, USA. mwool@oregon.uoregon.edu
Insights
Children develop early postural adjustments for gait initiation, but efficient reactions to balance threats emerge around 4-5 years old. This study tracked developmental changes in responses to perturbations during walking onset.
Area of Science:
- Developmental motor control
- Biomechanics of gait initiation
- Pediatric kinesiology
Background:
- Gait initiation involves complex postural adjustments.
- Understanding the development of these adjustments is crucial for pediatric motor development research.
- Early childhood walking development shows significant variability in response to external stimuli.
Purpose of the Study:
- To investigate the developmental trajectory of integrating postural adjustments during gait initiation in children.
- To identify the age at which children effectively respond to external balance perturbations during gait initiation.
- To analyze kinematic and electromyographic (EMG) changes associated with developing balance control in young walkers.
Main Methods:
- Utilized kinematic and electromyographic (EMG) analysis to assess motor responses.
- Employed a magnetic perturbation system to resist gait initiation on a force platform.
- Compared responses across distinct age groups: 1-year-olds, 2-3-year-olds, 4-5-year-olds, and adults.
Main Results:
- The capacity for preparatory postural adjustments during gait initiation is present early in development.
- Efficient reactive responses to balance perturbations during gait initiation are not established until 4-5 years of age.
- Younger children exhibited variable, primitive responses, while older children showed significant increases in trunk/leg oscillations and delayed, amplified muscle responses with coactivation.
Conclusions:
- While basic postural adjustments emerge early, sophisticated reactive balance control during gait initiation matures later in childhood.
- A distinct shift in motor response patterns occurs around 4-5 years of age, indicating improved reactive strategies.
- These findings highlight critical developmental milestones in pediatric balance and gait control.
Abstract:
The development of the ability to integrate postural adjustments into the gait initiation process was investigated in children, using both kinematic and electromyographic (EMG) analysis. Subjects included children of 1 year of age (1-4 months' walking experience), 2-3 years of age (9-17 months' walking experience), 4-5 years of age (3-4 years' walking experience), and adults. We perturbed the balance of the children during gait initiation to determine the point at which infants begin to develop and finally master the ability to respond to external threats to balance during the gait initiation process. A magnet attached to the force platform on which the child stood was activated and served to resist the child's gait initiation (metal plaques on the soles of the shoes were attracted by the magnet) and thus served as an external perturbation during the gait initiation process. Kinematic and EMG analysis indicated that, while the ability to use preparatory postural adjustments in the gait initiation process emerges early in development, the ability to react efficiently to perturbations during gait initiation does not develop until after about 4-5 years of age. Though even the youngest age groups showed some response to the perturbation, it was highly variable, indicating its primitive form. The main response to the perturbation was a slight decrease in latency and increase in amplitude in the muscles used for push-off for gait initiation. Interestingly there was a shift in response pattern at 4-5 years of age, in both kinematic and EMG patterns. The amplitudes of the lateral and anteroposterior trunk and stance leg oscillations were significantly increased. In addition, the muscle response amplitudes (hamstrings and second quadriceps burst) of the swing leg were significantly increased and delayed (hamstring and gastrocnemius), with coactivation of agonist and antagonist muscles at the knee and ankle joint, concomitant with an exaggerated foot height of the first step.
