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Influence of vertical posture development on the velocity properties of triceps surae muscle in normal children
Insights
Early childhood muscle development shows changes in contraction time after infants begin walking. Standing upright influences triceps surae muscle properties, affecting how quickly muscles contract.
Area of Science:
- Pediatric Physiology
- Muscle Biology
- Developmental Motor Control
Background:
- Infants develop postural control and motor skills during their first year.
- The transition to upright stance involves significant neuromuscular adaptations.
- Understanding muscle property changes is crucial for developmental insights.
Purpose of the Study:
- To investigate changes in triceps surae muscle contractile properties in children.
- To determine the effect of early upright posture development on muscle function.
Main Methods:
- Studied 9 normal children at the onset of independent standing and 6 weeks later.
- Measured isometric twitch contraction time and half-relaxation time.
- Utilized supramaximal indirect stimulation to assess muscle velocity properties.
Main Results:
- Contraction time of the triceps surae muscle significantly prolonged after children began standing.
- Half-relaxation time remained unchanged during the study period.
- Prolongation of contraction time reached levels comparable to 3-year-olds and adults.
Conclusions:
- The development of vertical posture influences triceps surae muscle contractile properties.
- Long-term muscle activation in supporting upright posture is a key factor.
- These adaptations highlight the neuromuscular plasticity during early development.
Abstract:
Contraction time and half-relaxation time of triceps surae muscle were studied in 9 normal children immediately after they began to stand alone and again 6 weeks later. The velocity properties of the muscle were recorded during isometric twitch induced by supramaximal indirect stimulation. The development of the vertical posture at the end of the first year was found to be associated with prolongation of the contraction time, reaching values observed in 3-year-old children and adults. During the same period the half-relaxation time did not change. Data are reported to show that the influence of the vertical posture on the contraction time is due to changes in the contractile properties of the muscle. It is assumed that the velocity properties of triceps surae are influenced by the long-term activation of the muscle in supporting the vertical posture.