PhD, Associate Professor V.N. Shlyakhtov¹
Dr.Biol., Professor R.M. Gorodnichev^1
1Velikie Luki state academy of physical culture and sport, Velikie Luki

 

Keywords: electrical and magnetic stimulation, functional state, motor system of athletes, sports activity.

Background. The functional state of athletes is diagnosed, among other methods, by means of the electrical stimulation of different structures of the central nervous system, peripheral nerves, and the muscular system itself. The electrical stimulation of the above structures makes it possible to assess their excitability, the rate of excitation on the spinal cord and peripheral nerves, the amplitude of motor responses and a number of other parameters reflecting the state of the athletes’ motor system [1]. With the introduction of the magnetic stimulation method, the possibilities for testing the state of the human brain have increased [4]. Currently, the magnetic stimulation method has supplemented the understanding of the locomotion control mechanisms, and data have been obtained on the excitability of the motor zone of the cerebral cortex in individuals specializing in different sports and having different levels of sports mastership [3]. It should be noted that so far, no studies have been conducted to identify the specific effects of the magnetic stimulation and electrical stimulation when evaluating the functional state of different structures of the central nervous system in athletes.

Objective of the study was to identify special aspects of the use of magnetic and electrical stimulation for diagnosing athletes’ motor abilities.

Methods and structure of the study. The study involved 12 sprinters and 12 long-distance runners aged 17-26 years. The experimental protocol provided for registration of motor responses of the lower limb muscles caused by the magnetic and electrical stimulation of the spinal cord (level T11-T12) and the tibial nerve in the popliteal fossa, as well as registration of motor responses during magnetic stimulation of the motor zone of the cerebral cortex. The electrodes diverting electroactivity (EMG) were fixed on the biceps and rectus muscles of the thigh, soleus and anterior tibial muscles of the lower leg. EMG and electrical stimulation of the spinal cord and peripheral nerve were carried out according to the generally accepted method using Neuro-MEP 8 ("Neurosoft" LLC, Russia). The magnetic stimulation of the motor zone of the cerebral cortex was conducted using Magstim Rapid 2 (Magstim company, UK).

Results and conclusions. The statistical analysis has shown that during the magnetic stimulation of the brain, the long-distance runners have a higher amplitude of evoked motor response (EMR) of all tested muscles and lower thresholds of EMR as opposed to the sprinters. Thus, the mean group amplitude of EMR of the biceps muscles in the long-distance runners was 0.56±0.06 mV and in the sprinters - 0.19±0.02 mV (p<0.05). The threshold value of EMR of this muscle in the long-distance runners reached an average of 0.71±0.03 Tesla, 32.6% lower than in the sprinters. The differences in the EMR amplitude in the examined groups of athletes may depend on the unequal amount of subcutaneous fatty tissue due to the orientation of their training and competitive loads. It is well known that the use of electric current in muscle activation is largely determined by the amount of fat tissue. Another reason for the differences in the amplitude of EMR may be the higher number of slow motor units in the muscles of the long-distance runners with a low excitation threshold [1]. In terms of the EMR thresholds, the lower thresholds in the long-distance runners were probably determined by the large number of slow low-thresholds in the studied muscles.

The magnetic stimulation and electrical stimulation of the spinal cord and tibial nerve, on the whole, gave a similar orientation of the EMR parameters in different sports specializations. The long-distance runners’ EMR range in all muscles exceeded that in the sprinters, while the EMR threshold was lower for the long-distance runners. For example, during the magnetic stimulation of the spinal cord, the EMR amplitude in the rectus muscle in the long-distance runners exceeded that in the sprinters by 0.48 mV, and during the electrical stimulation – by 1.23 mV. A similar trend in the EMR amplitude was observed during the tibia stimulation.

It should be noted that the EMR amplitude in the muscles of the long-distance runners exceeded that in the sprinters more significantly during the electrical stimulation of the spinal cord and peripheral nerve than during the magnetic stimulation. Thus, the EMR amplitude in the soleus muscle of the long-distance runners during the electrical stimulation exceeded that in the sprinters by 213.1%, and during the magnetic stimulation - by 148.5% only. The above dynamics of the registered EMR shows a more significant differentiation of the functional state of the motor system in long-distance runners and sprinters under the electrical stimulation conditions. These peculiarities in the effects of the stimulation methods can be explained by the different nature of the magnetic stimulation and electrical stimulation. Under the influence of the magnetic stimulation, excitation of the nervous and muscular tissue occurs only with the presence of a mediator in the form of an induced electric field, and the electric stimulus penetrates each of these tissues through surface or needle-conducting electrodes [2]. Consequently, the electrical stimulation has a more localized effect on the excitable tissues, which probably also determines the peculiarities of motor responses caused by two types of stimulation.

Conclusion. The magnetic stimulation and electrical stimulation of the central nervous system and peripheral nerves can be used in the diagnostics of the functional state of the motor system in athletes. The advantage of the magnetic stimulation is that it can be used to assess the excitability of the cerebral cortex.

 

References

1. Gorodnichev R.M. Sports electroneuromyography. Velikiye Luki: VLSIPC publ., 2005. 230 p.

2. Nikitin S.S., Kurenkov A.L. Magnetic stimulation in diagnosis and treatment of diseases of nervous system: doctor's guide. M.: SAShKO publ., 2003. 378 p.

3. Pukhov A.M., Ivanov S.M., Machueva E.N. et al. Plasticity of human motor system under local physical activity. Ulyanovskiy mediko-biologicheskiy zhurnal.  2017.  № 1. pp. 114-122.

4. Barker А.Т., Jalinous R.А., Freeston I.L. Non-invasive magnetic stimulation of human motor corteх .Lancet. 1985.  V. l. pp. 1106-1107.

 

Corresponding author: shlyahtov@inbox.ru

 

Abstract

Objective of the study was to identify special aspects of the use of magnetic and electrical stimulation for diagnosing athletes’ motor abilities.

Methods and structure of the study. The study involved 12 sprinters and 12 long-distance runners aged 17-26 years. The experimental protocol provided for registration of motor responses of the lower limb muscles caused by the magnetic and electrical stimulation of the spinal cord (level T11-T12) and the tibial nerve in the popliteal fossa, as well as registration of motor responses during magnetic stimulation of the motor zone of the cerebral cortex. The electrodes diverting electroactivity (EMG) were fixed on the biceps and rectus muscles of the thigh, soleus and anterior tibial muscles of the lower leg.

Results and conclusions. During the magnetic stimulation of the brain, the long-distance runners were found to have a higher amplitude of evoked motor response (EMR) of all tested muscles and lower thresholds of EMR as opposed to the sprinters. Thus, the threshold value of EMR of the biceps muscle of the thigh in the long-distance runners was 32.6% lower than in the sprinters. The effects of the magnetic and electrical stimulation of the athletes’ spinal cord and tibial nerve were generally the same. The amplitude of EMR of all muscles of the long-distance runners exceeded that of the sprinters; the EMR threshold was lower in the long-distance runners. During the electrical stimulation of the spinal cord and peripheral nerve, the amplitude of EMR of the muscles of the long-distance runners exceeded that in the sprinters more significantly than during the magnetic stimulation. For example, during the electrical stimulation, the amplitude of EMR of the soleus muscle in the long-distance runners was 213.1% higher than that in the sprinters, and during the magnetic stimulation - only 148.5% higher. Under the influence of magnetic stimulation of the spinal cord, the amplitude of EMR of the rectus muscle of the thigh in the long-distance runners exceeded that in the sprinters by 0.48 mV, and during the electrical stimulation - by 1.23 mV. Similar changes in the EMR amplitude were observed when stimulating the tibial nerve. The obtained results expand the scope of knowledge related to diagnostics of the functional state of the athletes’ motor system by means of magnetic and electrical stimulation of the central nervous system structures.