Determination of Neuromuscular Control of the Upper Limbs in Children - Case Study Determination of Neuromuscular Control of the Upper Limbs in Children Case

: The objective of this case study is to observe the existence of an anticipation mechanism at the muscle groups level of the upper limbs. We tried to highlighted this anticipation process by measuring the potential of surface electric for some muscle groups representing the kine-matic chain on the right side, involved in the motor action of catching a basketball and a 3kg medicine ball with two hands to the chest. We conducted a case study of a 13-year-old child, female gender. As a measurement method, we used surface electromyography signals of the EMG Trigno Delsys wireless system with 16 electrodes. We determined the moment when the muscles come into action by increasing the potential of surface electric and the moment when the action of catching the ball takes place, using the information provided by the accel-erometers incorporated in the sensors of the Delsys equipment used. Therefore, we obtained information about how different muscle groups come into action which helped us to get an idea of how the child's movement is structured. Based on results of accelerations and EMG signals acquired we have formulated conclusions regarding the neuromuscular control of the tested subject. We also planned for the future to test a larger group of participants in the study research of anticipation mechanism in children who do not practice any performance sports.


Introduction
The research into the mechanism of anticipating human motor behavior is a challenge for both PhD students and researchers in sports science and physical education, because of movement that require sending a nerve command in the motor cortex which is involved in controlling voluntary body movements to initiate a motor action. Voluntary movement controlled by the cortex expresses the human intention to initiate an action through a pre-existing motor program anticipating the movement.
According to Pailhours andBonnard (1999, p.2160) the voluntary movement comes from a nervous command generated in the cortex which is called telekinetic, insofar as it expresses the intentions of the individual and where it may have different patterns due to the cognitive abilities of the human being.
According to Kandel et al. (2013, p. 862) the motor cortex although plays an essential role in controlling voluntary movements, its neurons do not function as spinal motor neurons whose unique role is to encode patterns of muscle activity. Instead, the motor cortex contains a heterogeneous population of neurons that contribute to several operations needed to convert an action plan into the motor controls that execute the motion pattern. The new evolutionary development in primates of a direct, monosynaptic projection on spinal motor neurons allows the primary motor cortex to control hand and finger movements in a uniquely skilled way. This feature was essential in acquiring the dexterity movements of the hand that only the upper primates possess and especially humans.
In this article we will highlight the values of an existing mechanism of anticipation due to the intention's effect of the predictive internal model ( on the muscles. The effect of telekinetic Kandel et al., 2013, pp.758-759) anticipation of a motor pre-action could be depend on the degree of development of the motor program that the child of our case study may have.
From our point of view, the term of telekinetic anticipation in this context expresses the various voluntary movements to which we attribute an intentionality for the body in the action of catching a ball.
The objective of our case study is to highlight the telekinetic anticipation mechanism for the learning area of a motor task by using an electrophysiological measurement technique.
The phenomenon of anticipation from the electrophysiological techniques point of view, demonstrates that the anticipatory processes can be observed only with a certain difficulty and as disconnected manifestations Bernstein, 1967, p.162) he surface electromyography (EMGS) is used in ( . T biomechanics to highlight the control of muscle contraction during effort, especially to be able to understand the role played by each muscle group in structuring an effective motor gesture (Hillerin, 2011, p.31). These processes can be observed before the movement begins when the weak bioelectrical manifestation of tonic impulses, involuntary, is not masked by the much Bernstein, 1967, p.163) stronger potentials that accompany muscle activity ( . An understanding of anticipatory muscle contraction in the devel- Ohashi, 1997) could opment of motor control as "being about something" ( be observed using the Delsys Trigno EMG wireless system with 16 electrodes. It requires knowledge of human anatomy because EMGS provides data on the analysis of the processing and recording of electrical signals between two or more recording electrodes placed on the muscles (Delafield-Gangopadhyay, Butt & 2013). election and placement of electrodes are important (Soltani & Vilas-S Boas, 2016) because the Delsys Trigno EMG wireless system measures the electrical signal associated with neural muscle activation, being an experimental technique that provides information about what is happening physiologically in the nerves and muscles, as well as information about sequences or synchronization over time of a several muscles activities. The importance of EMG wireless system is that it provides an objective assessment of when a muscle is active or not because it reflects electrical activity in the muscle fibers of the activated motor units (MU) where the electrical signal is proportional to the degree of muscle activation and it spreads over the muscle fibre surface (Hunter et al., 2002).
According to Hillerin (2011, p.34), electromyography is an application about the utility of understanding electrical phenomena for the performance sports domain and effort in general, as well as usefulness in physical education where the phenomenon of anticipation exists and continues to be the subject of research, but it is difficult to determine given the time of the order of milliseconds that requires advanced technical equipment to measure it.
We also mention other researches conducted over time which has shown that the posterior parietal cortex is involved in motor-sensor integration processes which allows the generation of predictive models, as well as the real-time estimation of the segmental position and the identification of the discrepancies between the anticipated consequences Baumann Müller versus real driving commands Brenton & , 2018;Bongaardt & Meijer, 2000;Botezatu & Andrei & Hillerin, 2014;Buckner et al., 2011;Gau et al., 2020;Macovei & Hillerin, 1997;Marin et al., 2015).

Research hypotheses
1. If we use surface electromyography (EMGs) then we could highlight the phenomenon of functional anticipation on the arm muscles in the execution of an absorption movement to catch a ball.
2. The measurement of the anticipation contraction is different both in relation to the task to be performed and for the muscle groups involved.
3. If we have different work tasks, then the anticipation time could also be different.

Research methods
The main research methods used were as following: • the bibliographic studying; • the observation method; • the laboratory experiment; • the case study • the data collection and data processing by filtering and RMS (the root mean square); • the mathematical method; • the graphic representation; • method of data analysis and interpretation. The subject of the research was a child 13-year-old, female gender, right-handed, who does not attend at any performance sport training and has no history of motor or neurological dysfunction. The participant was informed of the characteristics of the research and brought an informed written consent document signed by the parent.
1. The experiment took place at the Biomotor Laboratory of the National Institute for Sports Research, located on Bucharest, strictly following the rules of the World Health Organization (2020).
The work methodology was established as follows: before catching, the participant stood in a staggered stance with the legs apart and knees slightly bent, arms bent in front of the chest and hands with fingers slightly rounded and ready to catch the ball. In order to help the participant to perform the exercises, a researcher was located 2 m in front of her, with a similar staggered stance. The participant catches the ball with two hands to the chest by an absorption movement, hold the ball for 1-2 seconds and after that she throws the ball back to researcher. The participant was instructed to catch and throw the ball as fast as possible. In both exercises with the two different types of ball, the ball was caught in front of the chest and thrown directed towards the researcher and both legs were in contact with the ground throughout whole trial.
An accommodation period consisting of three repetitions of each exercise was performed prior to data collection. The participant was verbally instructed by the researcher on correct catching and throwing technique. A 3 min rest period between exercises was given to avoid muscular fatigue.
The participant performed three catches of the basketball and three catches with the medicine ball.

Results
Surface electromyography (EMG) signals were collected by using the EMG Trigno Delsys wireless system with 16 electrodes. An accelerometer is also incorporated in the composition of each sensor unit. We used 11 electrodes that were placed on the main muscle groups from kinematic chains involved in the absorption and propulsion movement of catching and throwing the ball to / from the chest with both hands.
A topographic marking of the different anatomical points was carried out to facilitate the placement of the electrodes and the skin zones for electrode locations were cleaned with an alcohol swab in order to reduce impedance. Then the surface electrodes were placed parallel to the muscle fibers to begin their electrical signals recording.
Using the dedicated software of the Trigno DelSys system, the information acquired using the EMG sensors was processed by filtering the signal for both acceleration and EMG signal and RMS (the root mean BRAIN. Broad Research in December, 2020 Artificial Intelligence and Neuroscience Volume 11, Issue 4, Supplementary 1 51 square) and then the data collected after filtering was exported to Excel. In this regard, we illustrated graphically the evolution of the acceleration over time and the surface electromyography (EMG) signals for the muscles monitored in order to observe what happens before catching the ball ( figure 1). From all the acceleration signals acquired we have chosen to use the one recorded from the sensor fixed on ED because it was the first segment that moved when the ball was caught.
Following the curves carefully, we identified the time t 0 when the forearm begins to move. On the x-axis of time in the surface electromyography (EMG) graph, we marked t 0 moment and tracked the muscle activity that precedes it, which is characteristic of the movement anticipation. On the acceleration graph, we analyzed the first decrease of the forearm acceleration in order to mark the t 1 -moment corresponding to the contact with the ball. The muscle activity between these two moments of time, t 0 and t 1 , represents the area of the contact anticipation, respectively the muscles preparation for contact. There are contractions between the interval t 0 -t 1 to a small extent for muscles monitored (TB, FCR, ED, BB and RA).
In order to participate in the preparation of contact with the ball, also have contractions during this time the muscles AD, TMF, TF and PM. Even before catching the medicine ball the activity of all muscle groups has been intensified. We can see that certain muscles groups come into action before the t 0 reference point like AD, TF, PM, TMF rather than TB, FCR, ED, BB (which have muscular coordination in the same time - figure 2). RA does not come into action before the same reference point shown above. Figure 2 shows how the muscle groups of TB, FCR, BB and ED acted. At t 1 -moment was made the synchronization of time variation curves of the potential electrical of the muscles involved. Following the data acquired and the graphs presented, we identified the reference points of the anticipation time values at t 0 and t 1 when the first movement of the forearm begins for each of the three catches of the ball.
In this regard, we have calculate the movement timing from the first contraction until the contact with a 3kg medicine ball (table 1). Once we discovered these reference points, we were able to observe in the participant how its muscles have prepared for the trials performed. Table 2 shows the maximum values of the EMG signals measured which are expressed in microvolts [µV] for each muscle involved in every of the three actions of movement. These values represent the maximum recorded before t 0 and between t 0 -t 1.  Figure 3 shows the same synchronization for the trunk and the abdominal muscle groups area. The overlap was not so good, which is a sign that every time the subject has organized its movements differently (as I said, the 13-year-old subject does not practice any sport in an organized way).  There is a contraction of anticipatory movement for three of the four muscle groups (TMF, TF and LD) presented above and, more strongly, another contraction in contact anticipation with the ball between t 1 -t 0 for the TB and BB muscles.
In the same way as for the medicine ball, we processed the data for catching a basketball. After we gained the data acquisitions we marked the reference points for the t 0 and t 1 -moment timing in order to observe in the participant's motor behavior how its muscles have prepared for the trials performed. The results obtained are represented in Table 3 for the time intervals delimited by the t 0 and t 1 moments.  Table 4 shows the maximum values of the EMG signals measured which are expressed in microvolts [µV] for each muscle involved in every of three motor actions representing the maximum recorded before t 0 and between t 0 -t 1.  Figure 5 shows the surface electromyography (EMG) signals for the TB, FCR, BB and ED muscles. To the right of the image are the variance curves of the surface electrical potentials for deltoid and biceps brachii. The timing was done all, the one that marks the contact with a basketball. It is observed how a pattern of movement is observed somewhat, but there are also variations that indicate a disorder in the organization of the movement.  Figure 6 shows the muscle activity recorded for the TMF, LD and TF muscle (left image) and for the RA and EO muscles (right image).

Conclusion
The results obtained demonstrate that the simple responses such as upper limbs extension can be produced with different neuromuscular pat-terns when the task was modified.
The coordination in the motor cortex is an important component of voluntary movement because specific anticipatory adjustments of certain postural muscles could provide the stable support needed to successfully complete the intended actions such as catching and throwing a ball as quickly as possible.
To the extent that postural muscle activity precedes and is specific to a given movement, it could be argued that muscle activity is a component of the voluntary response planning.
Regarding the time of information processing, the finding is relevant for improving the motor program because there may be an anticipation of movement even in the joint of the hand or fingers that initiates a motor act before muscle groups of other body segments.
The neuromuscular activity can be a component of a voluntary response which has implications for motor control models of response organization. This sort of feedforward mechanism may control both postural and task response components.
At this stage of learning, a complex motor action, like catching a ball of different sizes and weights, requires a stable connection between the systems involved in the trials, such as hand-eye coordination and telekinetic movement of the upper limbs. There is an anticipatory motor pattern activity in both work task and upper limbs muscles which was examined for catching a ball and may be considered a major component of voluntary bilateral arms extension.
Differences in the dominance of certain structural moment of anticipation related to the fact that the subject of the case study does not practice any sport can be revealed. But this does not mean that there is no representation (scheme or program) that determines certain aspects of the individual internal model according to the level of sports training. Even if it is currently a case study, the analyzes of the surface electromyography (EMG) signals indicate that there is a link between the evolution of anticipation times and the level of psychomotor training in the learning area, as well as the differences in anticipation of time between the catches.
Regarding the subject's age of our research as well as the lack of a training stage in any sport, we can highlight the existence of a weak telekinetic anticipation time, which shows that an internal learning model should be developed and supported from an early age less than 13 years. The participant's ability to use its own neural representation in a motor action requires future investigations of neural mapping during the execution of another motor task, in order to better highlight the mechanism of telekinetic anticipation.