INTRODUCTION

In our longstanding studies we have ascertained that unilateral changes of functional state of neuromuscular system (NMS), particularly, changing velocity of voluntary relaxation (VVR) of skeletal muscles under the influence of different adaptogenic factors, depend on the fact that each of such impacts is more or less accompanied by tissue hypoxia and hypoxemia, which causes activation (inclusion) of the whole complex of antihypoxic and defense reactions. The most economizing and antihypoxic effect is provided by non-specific inhibitory-relaxation functional protective system (IRFPS) of organism against extreme impacts of different adaptogenic factors, which are accompaniedby abrupt disturbances in homeostasis and by tissue hypoxia. IRFPS works on the following principle: information about abrupt disturbances in homeostasis and ratio of the most important homeostatic constants is transmitted to central nervous system (CNS) through the channel of afferent feedback; it causes activation of inhibitory processes, decrease of CNS excitability, normalization of relaxation process and considerable acceleration of all skeletal muscles relaxation at the same time (Vysochin Y. V., Denisenko Y.P., 2007).

METHODS

For studying of mechanisms of regulation and coordination of any movements, control over the contractile and relaxation characteristics of skeletal muscles, a functional condition of central nervous (СNS) and neuromuscular (NMS) of systems we used the method of a computer polymyografy developed by Yu.V.Vysochin which is applied by preparation of athletes of national teams of the USSR, Russia and showed high informational content and reliability.

RESULTS AND DISCUSSION

In several sets of experiments, in which sportsmen of different levels of proficiency and different specialization took part, we have found direct significant dependence between special exercise performance (SEP) and, of course, sport results and VVR of skeletal muscles. In most kinds of sport meaning of SEP in the progress of sport results, especially at the stage of higher sport mastery was considerably higher then meaning of contractile properties of muscles. This fact in no way means that contractile properties of muscles do not play any role in efficiency mechanisms. On the contrary, they are very important because muscles contraction provide physical action. And duration of this work, i.e. exercise tolerance and, correspondingly, special exercise performance considerably depend on relaxation characteristics of muscles. The above-mentioned facts, in our opinion, are quite important for understanding of the role of miorelaxation in increase of SEP in all kinds of sport activities, because in each of them there are very high requirements in velocity, velocity tolerance or coordination, or different combination of these qualities, which directly depend on muscles VVR.

CONCLUSIONS

Experimentally big advantages of relaxation type of long-term adaptation were proved; this type of adaptation develops at sportsmen with high VVR of muscles and highly active IRFPS, and it provides achievement of the highest levels of exercise performance and preservation of health in extreme conditions at the same time. We also ascertained that heightened excitability of CNS is the main.