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Development of anticipatory postural adjustments during locomotion in children
1Karolinska Institute, Nobel Institute for Neurophysiology, Stockholm, Sweden.
Insights
Children
Area of Science:
- Motor Control
- Developmental Neuroscience
- Biomechanics
Background:
- Anticipatory postural adjustments (APAs) are crucial for maintaining balance during voluntary movements.
- Understanding the developmental trajectory of APAs in children is essential for identifying motor control maturation.
- Previous research has primarily focused on adult APA mechanisms.
Purpose of the Study:
- To investigate age-related changes in anticipatory postural adjustments during treadmill walking in children.
- To examine the influence of the step cycle phase on postural and voluntary muscle activity latencies.
- To characterize the developmental patterns of specific muscle activation during APAs.
Main Methods:
- Electromyography (EMG) and movement analysis were used to record muscle activity and kinematics from the arm and leg.
- Children aged 6-14 years walked on a treadmill while performing a pulling task.
- Latencies to muscle activation were measured relative to an auditory cue and analyzed based on age and step cycle phase.
Main Results:
- Postural leg muscle activity consistently preceded voluntary arm muscle activity across all age groups.
- Muscle activation latencies decreased with age, indicating faster responses in older children.
- Younger children exhibited less phase-dependent modulation of postural responses and delayed voluntary activity, suggesting developmental differences in motor planning and execution.
Conclusions:
- Anticipatory postural adjustments mature progressively from 6 to 14 years of age.
- Developmental changes in motor control include improved timing and phase-dependent modulation of postural responses.
- Immature postural muscle activation patterns in young children may reflect a non-fully developed motor control system.
Abstract:
1. Anticipatory postural adjustments were studied in children (6-14 yr of age) walking on a treadmill while pulling a handle. Electromyographs (EMGs) and movements were recorded from the left arm and leg. 2. Postural activity in the leg muscles preceded voluntary arm muscle activity in all age groups, including the youngest children (6 yr of age). The latency to both leg and arm muscle activity, from a triggering audio signal, decreased with age. 3. In older children the latency to both voluntary and postural activity was influenced by the phase of the step cycle. The shortest latency to the first activated postural muscle occurred during single support phase in combination with a long latency to arm muscle activity. 4. In the youngest children, there was no phase-dependent modulation of the latency to the activation of the postural muscles. The voluntary activity was delayed during the beginning of the support phase resulting in a long delay between leg and arm muscle activity. 5. The postural muscle activation pattern was modified in a phase-dependent manner in all children. Lateral gastrocnemius (LG) and hamstring muscles (HAM) were activated during the early support phase, whereas tibialis anterior (TA) and quadriceps (Q) muscles were activated during the late support phase and during the swing phase. However, in the 6-yr-old children, LG was also activated in the swing phase. LG was activated before the HAM activity in the youngest children but after HAM in 14-yr-old children and adults. 6. The occurrence of LG activity in postural responses before heel strike suggests an immature (nonplantigrade) gating of postural activity.(ABSTRACT TRUNCATED AT 250 WORDS)