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FEATURES OF HUMAN SPINAL INHIBITION DURING VOLUNTARY MOTOR ACTIVITY IN PERSONS DOING INCREASING INTENSITY GRADED PHYSICAL EXERCISES SPORTS

A. A. CHELNOKOV (1), L. T. KOSHKAREV (1), M. I. CHELNOKOVA (2) 1-VELIKIE LUKI STATE ACADEMY OF PHYSICAL EDUCATION AND SPORTS, VELIKIE LUKI, RUSSIA, 2-STATE AGRICULTURAL ACADEMY OF VELIKIE LUKI, VELIKIE LUKI, RUSSIA

Objective: the purpose of the research was to study of different types of spinal inhibition when performing voluntary movements in persons doing increasing intensity graded physical exercises sports. Materials and methods: 45 male took part in the research. Presynaptic inhibition of Ia afferents of soleus was evaluated using the technique of Y. Mizuno et al., nonreciprocal inhibition of α-motoneurons - by E. Pierrot-Deseilligny et al, and reciprocal inhibition of α-motoneurons - by C. Crone et al., in the state of relative muscular rest and during a 30-second isometric contraction with a force of 25% maximum voluntary contraction (MVC) using the multijoint medical-diagnostic complex «Biodex».
Results: it was established that weakening of inhibitory processes occurred in comparison with the state of relative muscular rest in the course of a 30-second isometric contraction; this pattern is related to the specificity of supraspinal excitatory and inhibitory effects on Ia and Ib interneurons in the spinal cord when performing a voluntary movement. The voluntary movement performed for 30 seconds was accompanied by an increased activity of the presynaptic inhibition of Ia afferents of foot flexor, unlike reciprocal and nonreciprocal inhibition.
Conclusions: the voluntary movement presynaptic inhibition must be actively regulating the excess afferent input to α-motoneurons of agonist and antagonist lower leg muscles, accelerating nonreciprocal and reciprocal inhibitory effects rendered on them, providing normal motor activity in man. New data derived from such research can be a theoretical basis for the study of physiological patterns of involvement of cortical and spinal neuronal inhibition networks underlying motor tasks of different complexity in athletes.
Keywords: 
presynaptic inhibition; nonreciprocal inhibition; reciprocal inhibition; H-reflex; muscles; Ia and Ib afferents; α-motoneurons; voluntary motor activity.