Dr.Biol., Professor  R.V. Tambovtseva¹
Postgraduate D.I. Sechin^1
1Russian State University of Physical Education, Sport, Youth and Tourism (SCOLIPE), Moscow

Keywords: normoxia, hypoxia, sensory and motor functions, combat athletes, reaction time, light, sound, choice.

Background. The interest in the psychophysiological characteristics of combat athletes stems from the factors causing different pathogenic mechanisms of hypoxic conditions, i.e. the use of submission holds (mechanical blockage of respiration; "blood constriction" by compressing carotid arteries and blocking the blood flow to the brain, etc.) and excessive functional loads [3, 4]. Load hypoxia, which results from excessive functional loads, leads to the disruption of oxidative phosphorylation in mitochondria and decreased activity of energy-dependent processes associated with acidosis and loss of energy substrates. Submission holds prevent an opponent from the effective realization of motor programs and cause unconsciousness, which leads to a negative impact on the competitive result and a reduction in the efficiency of motor programs. Therefore, an important element of athletic performance is the athlete’s ability to execute motor programs, when hypoxic conditions occur [5, 6], at the level necessary to eliminate the influence of the factors causing these conditions.
Objective of the study was to assess the stability of sensory and motor functions in highly qualified combat athletes after hypoxic stimulation.
Methods and structure of the study. The experiment was run at the Research Laboratory of the N.I. Volkov Sports Biochemistry and Bioenergy Department at Russian State University of Physical Education, Sports, Youth and Tourism. Sampled for the experiment were 15 combat athletes (engaged in judo and mixed martial arts) aged 20-25 years and having various sports qualifications: from CMS to WCMS. All subjects gave their written consent to participate in the experiment with the use of hypoxic stimulation. The athletes' psychophysiological characteristics were determined using the hardware and software complex "Sports psychophysiologist" [1] and the hypoxicator "Everest-1, v. 07m" (hypoxic test method).
The experiment was carried out according to the following program: 1. A preliminary psychophysiological study aimed to obtain the indices of thinking, motor responses, and functions under normal conditions. 2. Experimental exposure to normobaric hypoxia (10% oxygen gas mixture) for 30 minutes in standard laboratory conditions. 3. Re-testing of psychophysiological characteristics aimed to detect changes in the indices of thinking, motor responses, and functions under the influence of the hypoxic stimulus.
Results and discussion. Table 1 presents the response and central delay rates, which indicate a decrease in the response rate under the influence of the hypoxic stimulus.

Table 1. Response and central delay rates in combat athletes

Note: * - the differences are significant at p<0.05; LRT – light response time; SRT – sound response time; CRT – choice reaction time; CDR – central delay response.

In addition, there was a statistically significant decrease in the sensorimotor reaction rate in the dominant hand. This indicator in the non-dominant hand indicated a similar trend to that observed in dominant one. The sensorimotor reaction rate in the lower limbs was characterized by a mixed trend, which was not confirmed by the statistically significant differences, except for the light response time for the non-dominant leg.
Table 2 presents the thinking indices in the athletes (individual minute, errors made when learning the angular velocity of object motion, errors made when assessing the segments, errors made when assessing and learning the angles).

Table 2. Thinking indices in combat athletes

Note: * – the differences are significant at p<0.05

The "Individual Minute" test conducted using the hypoxic stimulus revealed no changes in the athletes' psychoemotional state. The reduction in the percentage of errors after the removal of the hypoxic stimulus was at the level of a strong tendency, and in the case of errors made while measuring the segments, this tendency was statistically significant (p<0.05).
Tables 3 and 4 present the dynamics of changes in the hand movement rate per 60 sec, however, these changes are not significant.

Table 3. Dynamics of changes in hand movement rate in combat athletes under conditions of normoxia and hypoxia (number of taps per 10 sec)

The dynamics of the dominant hand movement rate did not change statistically significantly, namely, there was an increase in the number of taps in the 1st and 6th 10sec intervals and a slight decrease in the number of taps from the 2nd to 5th 10sec intervals. The dynamics of changes in the non-dominant hand movement rate under the influence of the hypoxic stimulus was found to be similar to that of the dominant hand.
Table 4 presents the dynamics of changes in the leg movement rate in the combat athletes under the conditions of normoxia and hypoxia.

Table 4. Dynamics of changes in leg movement rate in combat athletes under conditions of normoxia and hypoxia (number of taps per 10 sec)

It was shown that the detected changes in the leg movement rate were similar to that of hand movements and were not statistically significant. This phenomenon, being associated with a decrease in the limb movement speed under the influence of the hypoxic stimulus, can subsequently be viewed as a factor that negatively affects the athletes' performance as they advance in the tournament bracket.
Table 5 present the indices of functional mobility (lability) of the visual sensory and central nervous systems during information perception and processing.

Table 5. Indices of critical frequency of light flashing and paired light pulses

Note: * – the differences are significant at p<0.05; CFLF – critical frequency of light flashing; CFPLP – critical frequency of paired light pulses.

The findings showed the statistically significant changes in the critical frequency of light flashing and paired light pulses, which in our case reflected increased eye fatigue in the athletes.
Conclusions:
• The combat athletes were found to have a high degree of psychophysiological stability and a pronounced ergogenic effect of hypoxic stimulation. These phenomena were due to the specificity of the training and competitive activities within the sports disciplines in question and the presence of submission elements, which are mentioned in the list of technical actions permitted for use in the competitions.
• The analysis of the tabular values revealed no pronounced negative changes in the psychophysiological characteristics under study. Although the athletes were found to have increased eye fatigue, under the conditions of hypoxia their reaction time reduced, so did the number of errors made when performing the tasks related to thinking.
• Apart from the benefits of the phenomenon under study, coaches and athletes must consider the negative changes associated with the decrease in the limb movement rates and the increase in the degree of eye fatigue, which may have a negative impact on the athletes' performance as they advance in the tournament bracket.
• Given the provisions presented, it is reasonable to make preliminary use of hypoxic tests to predict changes in the psychophysiological characteristics of athletes. The data obtained may be potentially important for individual planning of athletic training.

References

1. Koryagina Yu.V., Nopin S.V. Hardware and software systems to study athletes' psychophysiological characteristics. Voprosy funktsionalnoy podgotovki v sporte vysshikh dostizheniy. 2013. v. 1. no,1. pp. 70-78.
2. Nesterov S.V. Effect of acute experimental hypoxia on cerebral circulation and autonomic regulation of heart rate in man. PhD diss. abstr., Sechenov IEPB. RAS. Saint Petersburg, 2004. 20 p.
3. Rules of “judo” sport (approved by the order of the Ministry of Sports of Russia dated 01.06.2017 No. 482).
4. Order of the Ministry of Sports of Russia dated 02.02.2016 No. 92 “On approval of the rules of "mixed martial arts "(MMA) sport".

Corresponding author: ritta7@mail.ru

Abstract
Objective of the study was to test stability of sensory and motor functions in highly qualified combat athletes after hypoxic stimulation.
Methods and structure of the study. The experiment ran at the Muscular Activity Bioenergy Laboratory of the N.I. Volkov Sports Biochemistry and Bioenergy Department. Sampled for the experiment were 15 athletes aged 20 to 25 years. The study was conducted according to the standard laboratory program using psychophysiological and hypoxic tests.
Results of the study. The study found a pronounced ergogenic effect of hypoxic stimulation on the psychomotor system of athletes, associated primarily with the sport-specific peculiarities of the training and competitive activities and presence of chokeholds.
Conclusion. Based on the analysis of the table values, it was concluded that there were no pronounced negative changes in all the psychophysiological indicators under study. Despite increased fatigue of the visual analyzer resulting from hypoxic stimulation, there was a decrease in the reaction time and in the number of errors made when completing the tasks related to mental activity.