PhD N.A. Gross¹
PhD T.L. Sharova¹
A.V. Molokanov^1
1Federal Scientific Center for Physical Culture and Sports, Moscow

Keywords: disabled children, functional response of the body, vestibular stimulation.

Background. The development of statokinetic stability is a prerequisite for the development of motor skills in disabled children. The key links of the statokinetic stability are the vestibular and proprioceptive systems, the stimulation of which is important for the regulation of the equilibrium function when performing the simplest movements. The vestibular apparatus is a part of the most complex mechanism allowing orienting in space and maintaining body balance when walking and performing various complex coordination movements. The vestibular apparatus is not simply an organ of equilibration but also a sensory system that helps perceive angular and linear accelerations, transform mechanical energy into the nerve signals that coordinate the autonomic nervous system (ANS) when changing the head or body position. The vestibular system receptors - vision, proprioceptive foot sensitivity, skin receptors - help recognize the spatial position of the body with a considerably precise determination of own position. In response, there are reflex contractions of the muscles, contributing to body straightening and postural equilibrium [1, 2].
Various external factors, as well as a number of pathological conditions related to the functional or organic changes in the vestibular system, cause changes in the overall functional state of the body [3, 5].
If a child gets used to moving horizontally, unusual upward and downward movements or lateral movements may cause dizziness, nausea, and disorientation. ANS response to a motor action is a symptom of bodily dysfunction. It may be a display of a disease of the nervous, cardiovascular, respiratory systems, or gastrointestinal tract.
In children with motor disabilities, vestibular dysfunction becomes evident at the early stages of the disease and is accompanied by disequilibrium and lack of pressure on the bottoms of the feet, which can cause pathological vegetative reactions when changing to a vertical position [2, 4].
There is a functional relationship between the motor (proprioceptive) analyzer and the vegetative reaction: motor activity reduces the intensity of the vegetative reaction to the vestibular analyzer stimuli. Under the influence of special training, motor, and vegetative reflexes caused by the vestibular analyzer stimuli are reduced and disappear [5, 6].
The vestibular system training and stimulation of the soles reduce the excitability of the organ of equilibration and prevent undesirable phenomena in ANS. In this case, the cardiovascular reaction to sudden changes in the body position in space and the stimulation of the foot proprioceptors in children with motor disorders should be carefully studied [6].
Objective of the study was to analyze the state of the cardiovascular system of disabled children during active exercises aimed to stimulate their vestibular system and support points of the feet when developing statokinetic stability.
Methods and structure of the study. We evaluated the functional response of the body of children diagnosed with cerebral palsy, autism, etc., including retarded development of psychomotor functions, at rest and after performing one exercise. The analysis was carried out based on the calculated endurance coefficient - EC (determined by the Kvas formula).
A child rotation test in "Gross’s simulator" was used to assess the cardiovascular reaction to changes in the spatial position of the body. The "Korvit" load simulator was used to assess the children’s bodily reaction to the stimulation of the plantar support zones.
Heart rate and blood pressure were measured before and after the test. When rotating in the Gross’s simulator, the child was in a vertical position, raised a short distance from the floor. The methodist rotated the child around its vertical axis, doing 15 revolutions in 30 seconds. Immediately during the 1st minute of recovery, the subjects’ heart rate and blood pressure were measured.
The irritating effect on the bottoms of the feet was provided by the plantar support load simulator "Korvit", which simulates the support resistance using the principle of pneumatic-mechanical pressure on the corresponding plantar support zones in real locomotion modes. Through this effect, the "simulator" forms a powerful afferent flow of impulses, which exert a regulatory effect on the central nervous system structures that controls movements, thus activating the support reactions of the feet. The 5-min "Slow Walk" mode was used to determine the functional response of the child’s body by measuring heart rate before and after the use of the "simulator".
The functional state of the cardiovascular system was rated using the Quaas formula to calculate the endurance coefficient based on the pulse rate and pulse pressure. The endurance coefficient is said to reflect the contractile function of the myocardium, the level of training, and the psychophysiological state of the body.
Normal endurance coefficient varies between 12 and 16. Its upward trend indicates weakened cardiac activity and is deemed an indicator of the vascular system detraining. Decreased endurance coefficient testifies to the improvement in heart activity. Moreover, the analysis of the types of the cardiovascular responses according to general assessment (1 - good adaptation, 4 – intense adaptation) that indicates the pathway to adaptation.
Sampled for the study were three groups of children: Group 1 - children diagnosed with cerebral palsy, Group 2 – those diagnosed with autistic spectrum disorders, Group 3 – those with other diagnoses, primarily with psychomotor retardation.
Results and discussion. The data on the cardiovascular reactions to the rotations in the Gross’s simulator are presented in Table 1.

Table 1. Cardiovascular reactions in children with disabilities from different groups tested in Gross’s simulator

All groups of children were found to have weakened cardiovascular function, as evidenced by the large deviation of the Quaas coefficient from the norm. At the same time, in children with autistic spectrum disorders and other diseases, who are more active in life, the endurance coefficient indicated a better functional endurance of the cardiovascular system than in the children with cerebral palsy.
After the test, which caused vestibular irritation, the children with cerebral palsy and autism were found to have the endurance coefficient rate improved in most cases (75% and 57%, respectively) than the children with other diagnoses - 40%.
The endurance coefficient increase proves the great potential of disabled children and they need to be engaged in active physical exercise.
Concerning the types of the cardiovascular response to physical loads, the test results showed that the improvement and deterioration were similar in all three groups: improvement - 20 to 35%, deterioration - 25 to 40%, no change - 10 to 55%.
The effects of the plantar support load simulator in the "Slow Walk" mode on the disabled children’s cardiovascular are presented in Table 2.

Table 2. Comparative data on changes in heart rate at rest and after physical loads using "Simulator"

The use of the "Simulator" at rest and after physical loads was accompanied by the increased pulse rate (in 70.6% of cases at rest and 85.2% - after exercise), which testifies to its functional effect on the children’s body. Decreased heart rate or unchanged condition indicates that individual children were not affected. This may be due to the fact that children who can walk constantly experience natural stimulation of the feet and the "Slow Walk" mode does not affect them greatly.
The fact that heart rate increases after the use of "simulator" indicates that this functional stress method is similar to natural walking and can contribute to the improvement of statokinetic reactions of the body.
Conclusions. In the initial state, the children of all groups were found to have a weakened cardiovascular system activity.
• Vestibular stimulation caused changes in the cardiovascular response relative to the initial state. Rotations in the Gross’s simulator contribute to the improvement in the functional response of the cardiovascular system of disabled children.
• The use of the plantar support load simulator "Korvit" in the "Slow Walk" mode affects the proprioceptive sensitivity of the foot, similarly to natural walking, which has a positive effect on statokinetic stability.

References

1. Barkhatova V.P. Neurotransmitters and extrapyramidal pathology. M.: Meditsina publ., 1988. 175 p.
2. Bernstein N.A. Physiology of movement and activity. M.: Nauka publ., 1990. 495 p.
3. Vasilevskiy N.N. On some biofeedback problems with feedback. Proc. 1st res.-practical conference “Biological feedback in medicine and sport”.». St. Petersburg, 1999. pp. 35-37.
4. Verner D. Rehabilitation of children with disabilities . M.: Filantrop publ., 1995. 654 p.
5. Verkhoshanskiy Yu.V. Basics of special physical training of athletes. M.: Fizkultura i sport publ., 1988. 148 p.
6. Gross N.A., Berkutova I.Yu., Goncharova G.A. Assessment of adaptation of physiological mechanisms in children with disabilities during exercise. Vestnik sportivnoy nauki. 2014. no. 6. pp. 46-48.

Corresponding author: rudra54@yandex.ru

Abstract
Objective of the study was to analyze the state of the cardiovascular system of disabled children during active exercises aimed to stimulate their vestibular apparatus and support points of the feet when developing statokinetic stability.
Methods and structure of the study. We evaluated the functional response of the body of children diagnosed with cerebral palsy, autism, etc., including retarded development of psychomotor functions, at rest and after performing one exercise. The analysis was carried out based on the calculated endurance coefficient - EC (determined by the Quaas formula).
Results of the study. The study showed that vestibular stimulation affects the cardiovascular response. It was found that, upon performing the test leading to vestibular stimulation, the endurance rates in the children with cerebral palsy and autism improved in most of the cases (75% and 57%, respectively), as opposed to the children with other diagnoses - 40%. As for the types of the cardiovascular response to such physical loads, the improvements and deteriorations in all three groups were approximately equal and amounted to: improvements - from 20 to 35%, deteriorations - from 25 to 40%, no changes - from 10 to 55%. The use of a "simulator" at rest and after training was accompanied by an increase in the heart rate (in 70.6% of cases at rest and in 85.2% after exercise), which indicated its functional effect on the children’s body.
Conclusion. In the initial state, the children of all groups were found to have a weakened cardiovascular system activity. Vestibular stimulation caused changes in the cardiovascular response relative to the initial state. Rotations in the Gross’s simulator contribute to the improvement in the functional response of the cardiovascular system of disabled children. The use of the plantar support load simulator "Korvit" in the "Slow Walk" mode affects the proprioceptive sensitivity of the foot, similarly to natural walking, which has a positive effect on statokinetic stability.