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Publication date: 01.07.2022
DOI: 10.51871/2782-6570_2022_01_02_1
UDC 796.071; 616-003.96
MANIFESTATIONS OF NEUROPLASTICITY IN NEUROMOTOR PARAMETERS OF ATHLETES OF VARIOUS SPORTS UNDER SUBMAXIMAL AND MAXIMAL LOADS
Yu.V. Koryagina, S.V. Nopin, S.M. Abutalimova, G.N. Ter-Akopov
FSBI “North-Caucasian Federal Research-Clinical Center of the Federal Medical and Biological Agency”, Essentuki, Russia
Annotation. The purpose of this study was to examine and compare neuromotor parameters in athletes, according to characteristics of the neuromuscular system at rest and under submaximal and maximal loads with different direction of the training process. The study involved 110 elite athletes (Masters of Sports and Masters of Sports of International Class). As a result of studying characteristics of the neuromuscular apparatus at rest (according to the data from stimulation electromyography), under submaximal (according to the data from surface electromyography when performing the Bosco repetitive jump test) and maximal (according to the data of surface electromyography when performing weightlifting exercises) loads, we have identified the manifestations of neuroplasticity, associated with fatigue compensation phenomena, urgent and long-term adaptive changes in the neuromuscular system to specific physical activity.
Keywords: neuroplasticity, neuromotorics, athletes, functional state, submaximal load, maximal load, neuromyography.
Introduction. Neuromotorics is the specifically organized type of motor activity, based on neuropsychology (connection of the brain functioning and mental functions) and directed towards developing functions of the brain structures through movement (motor skills). Voluntary movement (physical exercises, technique of motor actions) occurs under control of consciousness, manifestation of motor qualities – with participation of conation. Therefore, the neurodynamic characteristics of a man are a fusion of psychological and physiological mechanisms for managing movements, motor actions, reflected in the manifestation of various motor qualities. Athletic actions are described by not only the degree of perception, but also the structure of the main variables of movement: dynamic, temporal and spatial [1].
Scientists of the modern sports physiology, when analyzing central and peripheral mechanisms of adaptation to the specific sports activity, note with increasing frequency the phenomena of neuroplasticity [2] – the ability of neural networks in the brain to change through growth and reorganizing. These changes vary from separated neural pathways, which create new connections, to systematic correction, such as cortical remapping. According to the data given by different researchers, the adaptation of a man’s motor system to the specific sports activity is shown through changes of sensorimotor reactions [3-4], plastic functional rearrangements in the neuromuscular apparatus [5-7] and neural structures of motor control [8]. In this connection, studies of neuroplasticity in the characteristics of neuromotor processes of a man during sports activity are relevant.
The purpose of this study was to examine manifestations of neuroplasticity in neuromotor parameters of athletes, specialized in different sports.
Methods and organization. The study involved 110 elite athletes (Masters of Sports, Master of Sports of International Class). It included 12 boxers (women), 52 weightlifters (35 men and 17 women), track-and-field athletes (6 men), triathlon athletes (8 men), mixed martial artists (8 men), volleyball players (7 men), fencing (7 men) and field hockey players (10 men).
The muscle electroactivity characteristics at rest were identified with the stimulation electromyography (EMG). To identify motor response from the extensor digitorium brevis of the foot, innervated by the peroneus nerve, we have stimulated the following points: “tarsus”, “head of fibula” and “popliteal fossa” with the 4-channel hardware and software complex “Neuro-MVP” produced by Neurosoft (Ivanovo). The electric stimulation was made with rectangular pulses, stimulation time – 0.2 ms, the electric current was selected individually in the range of 15-30 mA.
The neuromotor parameters when performing the submaximal load was identified with the Bosco repetitive jump test (for boxers). The test (maximal vertical jumps for 60 s) is carried out on tensodynamic platforms with the recording electrophysiological signals using the wireless EMG. The program registers and analyzes following indicators: maximal push strength before the jump for each 15-second jump interval, average specific capacity of jumps, average jump height, mean root square deviation of the jump height, maximal jump height, number of jumps, values of bioelectric EMG potentials of the rectus femoris, the biceps femoris, the fibularis longus and the gastrocnemius (in each leg) for periods of 0-15 s, 15-30 s, 30-45 s, 45-60 s. We have calculated the fatigue index and the maximal push strength, maximal capacity and strength endurance.
We have also identified neuromotor parameters (according to the data from neuromyography) in athletes when performing competitive weightlifting exercises (under maximal load).
The study was carried out with the Smart BTS motion system. For the biomechanical analysis of movement and test exercises, we have developed special diagnostic protocols in form of computer programs for the BTS SMART-Clinic software:
1) “Bosco repetitive jump test” (Certificate of the computer program registration No. 2021619879, 18.06.2021) [9] (fig. 1);
2) “Biomechanical and electromyographic express evaluation of the weightlifting snatch” (Certificate of the computer program registration No. 2020660142, 28.08.2020) [10];
3) “Biomechanical and electromyographic express evaluation of the weightlifting clean and jerk” (Certificate of the computer program registration No. 2020660143, 28.08.2020) [11].
These programs allow a quick assessment of biomechanical and electrophysiological parameters of the competitive weightlifting exercises (fig. 2)
Fig. 1. Program window with test results
Fig. 2. Beginning of the Squat phase 3.2 (А – snatch, B – clean and jerk)
The programs register and record in result protocols temporal, strength, speed indicators, indicators of distance, kinematics, capacity, as well as electrophysiological parameters (average and maximal EMG amplitude of a muscle, dominating (peak), average and median frequency of the muscle bioelectric activity of the left and right trapezius, the quadriceps femoris, the biceps femoris and the gastrocnemius.
All test subjects gave an informed consent for participation in compliance with the WMA Declaration of Helsinki, as well as a permission for personal data processing. The study was approved by the bioethics committee in the FSBI “North-Caucasian Federal Research-Clinical Center of the Federal Medical and Biological Agency”.
The statistical data processing was made with the Statistica 13.0 software, differences between groups were identified with the Mann-Whitney U-test.
Results and discussion. Neuroplasticity in muscle electric activity characteristics in athletes at rest. The study of muscle electric activity indicators with the stimulation EMG has revealed that values of amplitude and M-response area in track-and-field athletes was higher (р⩽0.03) in the “tarsus” stimulation point (amplitude – 7.28±2.36 mV, area – 22.88±7.29 mV×ms), than in mixed martial artists (amplitude – 4.16±1.17 mV, area – 12.85±5.03 mV×ms). In the “head of fibula” and “popliteal fossa” points, the M-response amplitude of track-and-field athletes (“head of fibula” – 7.77±2.60 mV, “popliteal fossa” – 8.00±2.30 mV) differs significantly from the same indicator of triathlon athletes (“head of fibula” – 5.45±1.74 mV, р⩽0.01, “popliteal fossa” – 5.45±1.90 mV, р⩽0.03) (fig. 3).
Fig. 3. Motor response amplitude, registered from the extensor digitorium brevis when stimulating the peroneus nerve on the right in male athletes
The nerve conduction velocity (NCV) in the “tarsus” – “head of fibula” segment on the right in weightlifters (54.43±4.02 m/s) is statistically higher, than in triathlon athletes (48.43±5.03 m/s, р⩽0.04), volleyball players (48.44±2.61 m/s, р⩽0.004) and hockey players (49.33±3.89 m/s, р⩽0.02). The NCV in the “tarsus” – “head of fibula” segment on the left is higher in weightlifters (53.88±1.55 m/s), than in fencers (48.10±5.00 m/s, р⩽0.02), mixed martial artists (48.98±2.89 m/s, р⩽0.02) and field hockey players (49.73±3.70 m/s, р⩽0.02).
Therefore, the specific adaptation to sports activity characterizes the plasticity of the neuromuscular system in athletes. Athletes of cyclic and acyclic sports, who train mainly speed-strength qualities, have higher values of muscle fiber bioelectric activity compared to the parameters of athletes in situational sports.
Manifestations of neuroplasticity in neuromotor indicators of athletes when performing the Bosco repetitive jump test (under submaximal load). The study of neuromotor indicators in the lower extremities when performing the Bosco repetitive jump test has revealed that the greatest biomechanical parameters in female boxers during its 1st period were due to high stress, and therefore activation and synchronization of motor units primarily in the rectus femoris (1-4 period on the right: 1.46±0.59 mV; 1.39±0.55 mV; 1.16±0.54 mV; 1.30±0.48 mV; on the left: 1.10±0.29 mV; 0.65±0.33 mV; 1.24±0.29 mV; 1.25±0.59 mV). During the 3rd and the 4th period of the test, the stress in the biceps femoris that supports body stabilizing in case of landing and pushing becomes stronger (1-4 period on the right: 0.71±0.40 mV; 0.61±0.30 mV; 0.58±0.32 mV; 0.57±0.31 mV; on the left: 1.15±0.36 mV; 0.62±0.35 mV; 1.17±0.35 mV; 1.31±0.64 mV). This, as well as an increase of muscle electric activity in the left leg and a decrease of physical parameters by the end of the test (number and height of jumps) indicates the development of first compensated and then uncompensated fatigue.
Dynamics of electric activity indicators of leading muscles in the lower extremities that support jump movements during the multiple jump test allows describing local physiological processes and neuroplasticity phenomena, which cause the manifestation of functional capabilities and fatigue.
Manifestations of neuroplasticity in neuromotor parameters of athletes when performing competitive weightlifting exercises (under maximal load). When examining the amplitude and frequency parameters of the surface EMG of working muscles during performance of weightlifting exercises from the point of plasticity of the nervous system and neurodynamic properties [2], we have found a significant increase of EMG indicators within phases of the weightlifting snatch. Male weightlifters have shown multiple enhancements of the amplitude of muscle EMG, compared to the resting state, in separate occasions – up to 40 times. The electroactivity of the trapezius is increasing in both men and women. Average EMG amplitude within separate phases increases 33 times in women (average EMG amplitude of the left trapezius during the Squat phase 3.1) and up to 40 times in men (average EMG amplitude of the left trapezius during the Squat phase 3.1). The electric activity of all muscles increases more in men than in women. During performance of the exercises, the average EMG amplitude increases mainly, frequency characteristics change no more than 2.2 times (in women – the dominant (peak) frequency of the left biceps femoris in the Snatch phase 2.1; in men – the dominant (peak) frequency of the right trapezius in the Snatch phase 2.1).
Conclusion. Therefore, the conducted research of neuromotor parameters in athletes, according to the characteristics of the neuromuscular system at rest and under submaximal and maximal load has demonstrated manifestations of plasticity of these parameters, associated with compensation phenomena in case of fatigue, urgent and long-term adaptation changes of the neuromuscular system to specific physical loads.
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INFORMATION ABOUT THE AUTHORS:
Yulia Vladislavovna Koryagina – Doctor of Biological Sciences, Professor, Head of the Biomedical Technologies Center, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Sergej Victorovich Nopin – Candidate of Technical Sciences, Lead Researcher of the Biomedical Technologies Center, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Sabina Malikovna Abutalimova – Researcher of the Biomedical Technologies Center, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki.
Gukas Nikolaevich Ter-Akopov – General Director, FSBI “North-Caucasian Federal Research-Clinical Center of Federal Medical and Biological Agency”, Essentuki.
For citation: Koryagina Yu.V., Nopin S.V., Abutalimova S.M., Ter-Akopov G.N. Manifestations of neuroplasticity in neuromotor parameters of athletes of various sports under submaximal and maximal loads. Russian Journal of Sports Science: Medicine, Physiology, Training, 2022, vol. 1, no. 2. DOI: 10.51871/2782-6570_2022_01_02_1