[The facilitation and inhibition of monosynaptic reflexes in the upper extremity of nursing infants].

The upper extremity H-reflex was investigated in healthy children, aged from 3 to 15 months. The electromyographic reflex responses of m. abduct or digiti min.

Excitation-contraction latency in the muscles of children and adults.

Excitation-contraction latency in the fast flexor carpi ulnaris and in the slow triceps surae muscles was studied in healthy children aged one month, 10 months and three years, and in adults. The tests were carried out during isometric twitch following supramaximal indirect stimulation. Excitation-contraction latency was found to increase with age in both the fast and slow muscles.

Influence of vertical posture development on the velocity properties of triceps surae muscle in normal children.

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.

Dynamic properties of partially denervated muscle in children with brachial plexus birth palsy.

Contraction time, time to peak rate of tension development, half-relaxation time and maximum twitch tension of partially denervated flexor carpi ulnaris muscle were measured in children with brachial plexus birth palsy. The extent of weakness of the affected muscle was assessed by expressing its maximum twitch tension as a percentage of the tension of the contralateral normal muscle. Contraction time, time to peak rate and half-relaxation time were prolonged in children with severe weakness, while in children with moderate weakness only half-relaxation time was prolonged.

Force and contraction time relation in skeletal muscles of children and adults.

The force and contraction time relation was studied in twitch isometric contraction of flexor carpi ulnaris muscle (FCU) and triceps surae (TS) in 5-week-old infants, 3-year-old children and adults. Contraction time (CT), duration of the plateau of active state (PAS), and time of the decline of active state (DAS) do not change with increasing force of contraction of FCU in all three age groups and in TS in 5-week-old infants. CT and DAS decrease with increasing force of contraction in 3-year-old children and in adults.

[Staircase phenomenon in children with progressive muscular dystrophy and dermatomyositis].

The electrical and mechanical activity of the isometric twitch of flexor carpi ulnaris muscle during two per second indirect supramaximal stimulation for 90 sec was examined in 14 children with muscular distrophy and 8 children with dermatomyositis. The muscle electrical responses show no significant changes in the amplitude of its first negative phase. The first derivative of the dinamogram shows some of the following abnormalities in 8 of the examined children with muscular distrophy and in 2 of these with dermatomyositis: 1.