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Skeletal muscle characteristics in children 9-15 years old: force, relaxation rate and contraction time

E Bäckman1, K G Henriksson

  • 1Department of Neurophysiology, University of Linköping, Sweden.

Clinical Physiology (Oxford, England)
|October 1, 1988
PubMed

Insights

This study examined muscle function in children aged 9-15. Key findings show muscle relaxation rate is similar to adults, but contraction time and force-frequency relationships change with age.

Area of Science:

  • Pediatric Physiology
  • Neuromuscular Function
  • Exercise Science

Background:

  • Understanding pediatric neuromuscular development is crucial for assessing muscle function.
  • Limited data exists on age-related changes in specific muscle contractile properties during childhood.

Purpose of the Study:

  • To establish reference values for muscle contractile properties in children.
  • To investigate age and sex differences in relaxation rate (RR), half contraction time to tetanus (CTT1/2), and force-frequency relationships.

Main Methods:

  • Supramaximal electrical stimulation of the ulnar nerve in 77 children (aged 9-15).
  • Recording of adductor pollicis muscle isometric contractions.
  • Analysis of relaxation rate, CTT1/2, force-frequency curves, and a fatiguability test in a subset of participants.

Main Results:

  • No significant sex differences were observed in RR, CTT1/2, or force-frequency parameters.
  • Muscle relaxation rate (RR) was consistent across the studied age range and comparable to adult values.
  • Half contraction time to tetanus (CTT1/2) showed a trend towards being shortest at age 15.
  • The relative force at 10 Hz stimulation frequency increased with age, indicating age-dependent alterations in the force-frequency relationship.

Conclusions:

  • Pediatric muscle contractile properties exhibit specific developmental trajectories.
  • Relaxation rate appears mature early, while other parameters like CTT1/2 and force-frequency response continue to develop through adolescence.
  • Reference values for these parameters are provided, aiding in the assessment of neuromuscular function in children.

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