A.A. Grushin, professor, Ph.D., Honored trainer of the USSR and the Russian Federation
V.L. Rostovtsev, professor, Dr.Biol.
Smolensk State Academy of Physical Culture, Sport and Tourism, Smolensk

Key words: traditional, auxiliary training techniques, specific efficiency indicators, dynamic electrostimulation, main functional unit, athletic performance.

Introduction. Training process in almost every Olympic sport is characterized by the steady application programs of a certain number of training techniques and methods, their best combinations, the use of certain ratios of training intensity zones and amount of physical work. There are some athletes, who practice in approximately the same training regimen for many years, using conventional techniques and methods, repeating those types of training programs, which used to be effective for them. In addition, we can often see a cessation of growth of sports results, adapting to rising training load, fatigue and injury. It is necessary either to intensify the training process even more rigidly, or to introduce innovative effective techniques that contribute to immediate and long-term adaptation without the excessive intensification of physical load.

Problem statement. In the 80's of the last century, academician P.K. Anokhin carried out a series of experiments, in which it was found that while solving top-priority tasks a person faces (motor task as one of them) or while achieving, as the author put it, "the required result", a dominant - a consolidated system of involvement of energy-supply structures and mechanisms of that body part which is likely to perform this task, appears in the human body. All other structures adjust and help achieve the desired result [1]. Around the same time, professor I.P. Ratov suggested the idea of existence of the main units in the functional system of the human body [10].

Based on the findings of the research of these scientists, it is arguable that it suffices to affect the main functional units of athlete's neuromuscular apparatus for the changes to take place in the whole body.

In cross-country skiing two main functional units should be singled out in different phases of the skating stride cycle when moving along the distance: poling - it is the hand muscles (triceps muscle of arm - m. triceps brachi), the broadest muscle of back (m. latissimus dorsi) and the abdominal muscles (m.rectus abdominis) that are the tensest at this point. And pushing off with feet - it is the quadriceps muscle of thigh (m. quadriceps femoris) that is most tensed here.

Hence, a working hypothesis can be the fact that the auxiliary impact on at least one of the allocated functional units at the time of ultimate tension should lead to an enhancement of the entire motor pattern [11]. Moreover, we must provide the whole range of positive changes in the body of athletes, which, as numerous studies have shown, accompany the use of skin electrostimulation of muscles: improvement in circulation and lymph efflux [3,5,7], increase of cross-section of muscle tissue [13. 15], increase in physical strength [10], expansion in the number of macroergs (ATP, creatine phosphate and so on), increase in their enzymatic activity [2,4,6], oxygen utilization rate increase and reduction in muscle activity energy expenditure [8], increase of trophoenergetic processes, increase in the CNS activity and neurohumoral regulation of the body organs and tissues [9, 14].

The purpose of the study was to identify changes in special indicators of physical working capacity and sports result when using the aid of dynamic electrostimulation in the training process of cross-country skiers.

Materials and methods. In this study the m. quadriceps femoris was stimulated at the time of pushing off when moving using skating strides.

The characteristics of the test group of athletes are presented in Table 1.

Table 1. Age and qualification of the athletes of the test group.

The control test results (day 0 - the testing was conducted before the training sessions with the use of electrostimulation) are represented in Tables 2 and 3. In the current experiment, when analyzing the degree of impact of dynamic electrostimulation, we considered the indices of stride length - L_avg., m, frequency of steps - f avg., 1/min, maximum speed of movement in the track section  - V_avg., m/s. Besides, in the 30-meter track section we determined average heart rate - HR and sphygmic value (SV) of one meter of the distance. The sphygmic value of one meter of the distance was calculated by the HR formula: (V х 60), bpm [12]. The group equivalence was estimated by the indices of special fitness of the athletes. In each of the 4 attempts we timed the 2 strides of each athlete.

The athletes ran 4 laps non-stop, travelling in a circle 2400 m at the speed of 85-90% of competitive one. At the end of each lap the athletes accelerated at the specified ascending with competitive speed.

Table 2. Maximum speed of covering 30-meter track section with 5-degree ascending when moving using a V2 skating technique before experiment.

Based on the test results the athletes were divided pair-wise into equivalent groups: experimental - 5 people and control - 5 people. The experimental group used dynamic electrostimulation according to the developed program, the control one conducted all training sessions without dynamic electrostimulation. Both groups trained in accordance with one and the same methodology which was approved by the training council. All training sessions were conducted in natural training conditions in the snow when moving using skating strides. The classic experiment was carried out in Vuokatti (Finland).

Table 3. Stride length and frequency of steps in 30-meter track section with 5-degree ascending when moving using a V2 skating technique at maximum speed before experiment.

As seen from Tables 2 and 3, there are no significant differences between the registered indices.

Two objectives were set in this experiment:

1) to determine the efficiency of electrostimulation;

2) to determine the total training sessions with the use of electrostimulation and the number of sessions with electrostimulation per day.

For this purpose the experiment was planned as follows (Table 4): during the first 5 days the athletes from the experimental group used dynamic electrostimulation (DES) once a day, during the next 5 days of the study the experimental group was divided into two subgroups. One of which continued training once a day, the other trained using dynamic electrostimulation twice a day. During the second 5 days all athletes had two training sessions a day. 3 control tests were carried out, and neither of the athletes used dynamic electrostimulation.

Table 4. Classic experiment plan.

Starting from the 6^th day, the experimental group was divided into two subgroups:

Results and discussion.

Results of the 2^nd control test (after 5 days of training).

Тable 5. Changes in indices of special fitness in-between 1^st and 2^nd tests (after 5 days of training) in experimental and control groups (X±σ).

As the testing has shown, after 5 days of training no marked shifts in the 2^nd test were observed between the groups. In the experimental group an increase was marked in speed in the track section. The motor pattern trend in the athletes from different groups was also different. The stride length of the athletes from the experimental group increased compared with the control one. Such pattern of change in cross-country skiing was more efficient.

We determined significant changes in the indices during the 3^rd test.

Results of the 3^rd control test (after 10 days of training).

In the 3^rd test the trend of changes in the indices picked up even more: in the ascending section the speed in the experimental group increased owing to the longer stride length and lower frequency of steps compared with the control group (Table 6).

Table 6. Changes in indices of special fitness in-between 1^st and 3^rd tests in experimental and control groups (X±σ).

It turned out that dynamic electrostimulation had a major impact on special fitness and motor pattern of the athletes. There was a remarkable gain in speed when ascending. The 0,28 m/s difference in speed when ascending means that, at the speed of 7 m/s and, consequently, the result of 23 min 48 sec in the 10-km race, which is typical for the current period, the difference in time will be 40 sec or so (in case, when the race track includes an ascending of the mean steepness of 5 degrees). This difference in the athletic performance is impressive. According to other experiments (not listed here due to insufficient volume of the article), the winning edge of the experimental group after 7 training sessions with the use of dynamic electrostimulation is 18 sec compared with the control group.

Even more tangible differences were detected in the values of the sphygmic modes and the sphygmic value of one meter of the distance in-between the 1^st, 2^nd and 3^rd tests (Tables 7, 8).

Table 7. Changes in speed (V), HR and sphygmic value (SV) of one meter of distance in experimental and control groups in-between 1^st and 2^nd control tests (X±σ).

Table 8. Changes in speed (V), HR and sphygmic value (SV) of one meter of distance in experimental and control groups in-between 1^st and 3^rd control tests (X±σ).

It emerged that, compared with the control group, the speed of the athletes from the experimental group increased in advance in relation to the rise in the sphygmic level, which was expressed in significantly different changes in the sphygmic value of one meter of the distance in the 2^nd and, especially, in the 3^rd tests compared with the control one.

Conclusions. The tests have revealed a significant increase in the speed of moving using a V1 skating technique ascending, lowering of the sphygmic value of one meter of the distance, the upward trend of stride length at the same frequency of steps in the experimental group compared with the control group. All changes indicate the growth of special fitness of athletes in the experimental group, the efficient conversion of the motor pattern and the improved efficiency of the special structure of movements.

In the experimental group visible changes, caused by dynamic electrostimulation, took place upon the 5^th training session. In-between the fifth and tenth days of training the increase in the main indices turned out to be less sensible, however, it was significant compared with the first control test. Against the background of the already conducted 5 training sessions with the use of dynamic electrostimulation, dual trainings with the use of dynamic electrostimulation did not lead to any significant shifts.

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Corresponding author: grushin.aleksandr@mail.ru