[Structural variability of the functional system during activity and fatigue].

The object of the present paper is an analysis of factors causing considerable variability of functional systems (P. K. Anokhin) in their efferent part.

[Flexible and rigid connections in the regulation of motor activity].

The present investigation deals with the problem of versatile and rigid connections (N.P. Bechtereva), their functions and interrelations during repeated stereotype movements.

[Role of extrapolation and dynamic stereotype in the mechanisms of the formation and improvement of adequate motor coordinations].

Hardness (tonus), viscosity, bioelectric potentials, force and endurance of human muscles were studied. All these properties are subject to considerable alterations in conditions of fluctuations of muscle temperature, oxygen provision. They change permanently also in the process of dynamic work or static efforts (25, 50 and 75% of maximal strength).