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423D ANALYSIS OF TWO DIFFERENT DIFFICULTY ELEMENTS (ILLUSIONS) IN AEROBIC GYMNASTICS
UDC 796.058
Master, Postgraduate student Anita Lamosova1 Associated professor Svetlana M. Lukina2 Dr.Hab., PhD., Associated professor Ol'ga Kyselovicova1 Master, PhD., Assistant professor Adriana Krnacova1 Master, Postgraduate student Lucia Selecka1 1Comenius University in Bratislava, Faculty of Physical Education and Sports, Slovakia
2SPBU Saint Petersburg University, Department of Physical Culture and Sports, Russia
Corresponding author: svetlanaueg@rambler.ru
Abstract
Biomechanical considerations as reflected in correct or incorrect technique, particularly in aerobic gymnastics with still not enough scientifically approved knowledge are more than undoubted. The aim of the study was to identify and evaluate by the Simi Motion 3D system the kinematic characteristics in the specific phases of two different aerobic gymnastics difficulty elements: Free illusion to vertical split (FIVS) and Free illusion to free vertical (FIFVS), performed by the female athlete and Slovakian national team member (age = 21 years, sport age = 16 years, height = 159 cm, body weight = 52 kg). The indicators that appeared to be the key in terms of correct technique were detected: duration of phases, angular variables, height of center of mass and acceleration and velocity of the leading leg. The results showed the major error in the second phase of FIFVS where the minimum requirement (at least 170° between the legs in the split position) has not been reached and gymnast showed only 161.31° range. Additionally, a mistake in the position of standing leg, which must be perpendicular to the floor in the vertical split, was detected in both elements (FIVS = 83.04°; FIFVS = 77.58°).
Keywords: biomechanical analysis, time and spatial characteristics, free illusion to vertical split, free illusion to free vertical split.
Introduction. The Aerobic Gymnastics (AG) as a competitive sport claims many specific assumptions. Therefore, the training process has high demands to the volume, intensity, and technical elements with a high difficulty level. Aerobic gymnasts continuously perform high-intensity and complex movements following music patterns, which require coordination, anaerobic endurance, power and explosiveness, strength and flexibility. Certainly, such qualities give value and excitement to this sport. However, gymnasts in motor abilities that reflect on the quality of performance, accuracy of techniques and movements are different [2, 5].
The correct "model" technique and difficulty element forms are specified in the AG Code of Points, updated for each Olympic cycle [1]. Judges evaluate technical skills of all movements in the routine - diffi-
culty and acrobatic elements, aerobic movement patterns, transitions, links and many more. Perfect technique means performing movements without errors, with high precision, correct posture, body alignment and recognizable shapes of the elements performed. Small, medium, large or unacceptable errors have to be identified by the gymnasts and coaches, who will focus on whether the error is caused by a lack of concentration or by an inadequate physical training level [7, 8]. Importance of a correct technique is also shown in case of a tie at any place in qualifications or finals, where the tie is broken by the athlete with higher execution score. In addition, difficulty elements serve as means of challenging, as well as attesting the acquisition of targeted physical qualities and strings of movements.
Despite the growing popularity of AG, there is still a lack of biomechanical analyses in literature, regard-
ing the techniques of the specific difficulty elements [2, 4]. Biomechanical analysis is very efficient in order to improve, describe and develop specific technique. Moreover, it gives us the possibility to calculate various aspects of motion such as velocity, acceleration, displacement, time and further allows to analyze the angles of body segments relative to its reference frame or angles relative to different body parts [3]. Understanding the movement patterns allows us to uncover errors and specially to find ways to make the movement more effective and optimal from the view of correct technique.
For the purpose of the study we analysed the routines of individual women category from previous European and World Championships and selected one of the most frequently occurred difficulty elements - free illusion in two different variations: 1) Free illusion to vertical split, 2) Free illusion to free vertical split. The aim then is to evaluate the temporal and spatial characteristics in the specific phases of the selected elements with the aspect of correct technique.
Research methods and organization. A senior Slovakian team member female aerobic gymnast (age = 21 years, sport age = 16 years, height = 159 cm, body weight = 52 kg) was involved in the investigation. After being informed on the procedures and methods, the gymnast signed the consent form to participate in the study. The experimental protocol was performed in accordance with the Declaration of Helsinki for human experimentation and was approved by the university ethical committee. Two difficulty elements Group D (balance & flexibility) have been investigated: Free illusion to vertical split (FIVS, Fig. 1), difficulty value of 0.6 points and Free illusion to free vertical split (FIFVS, Fig. 2), difficulty value of 0.7 points. The only difference in execution of the elements is in the second phase, where the vertical split is performed with or without the support of both hands to the floor.
Data recording and collecting were processed via SIMI Motion 3D system, version 8.5 German company SIMI Reality Motion Systems GmbH [3, 4] by 8 synchronized high-speed infrared cameras. 20 anthropo-metric points were assigned and marked by passive retrospective stickers (Fig. 3). Temporal and spatial variable were observed: duration of selected phases of the elements, acceleration (a) and velocity (v) of the leading leg., height of the centre of the mass (CM). For easier analysis of the elements we select 2 phases for each: 1st phase represents "illusion", 2nd phase depict "vertical split".
Figure 3. Anthropometric points & marker placements
Results and discussion. Temporal variables. We assumed that duration of the 1st phase of FIFVS will be affected by more difficult position in the unsupported vertical split, and thus it will be longer than the 1st phase of FIVS. However, in both elements, the performance time of the 1st phase was exactly equal (1.30 s). Comparison of the 2nd phase shows only 0.02 s difference in favour of a faster executed vertical split in FIVS. Flexibility and balance are dominant qualities of the illusion elements. However, they do not guarantee the correct execution with the necessary range and intensity as the importance of velocity and acceleration has been approved in several gymnastic studies [6, 8, 9, 10]. In our investigation maximum acceleration (a) and maximum velocity (v) of the leading leg was measured on the malleolus point. More detail values of both elements are described in Table 1.
Figure 1. Free illusion to vertical split (FIG 2017)
Table 1. Maximal acceleration (a ) & maximal ve-
v max7
locity (v )
max
1st phase of the elements 2nd phase of the elements
a [m.s-2] v [m.s-1] a [m.s-2] v [m.s-1]
FIVS 64.14 7.72 42.39 6.06
FIFVS 65.13 8.02 45.07 5.70
Angular variables. The most important parameter Figure 2. Free illusion to free vertical split (FIG 2017) could be seen in the maximum range between legs in
vertical split, where the angle of 170° was expected as minimum requirement given by the rules. In FIVS a sufficient range of 177.77° was reached, however, only 161.31° in FIFVS.
Height & trajectory of CM. In the starting position of FIVS the CM was at 0.94 m. The highest point of the CM was detected at the end of the first phase at 0.98 m, unsurprisingly higher than the starting position as the gymnast performed on tiptoe. The lowest point of the CM was determined while entering the second phase (0.61 m). As expected, in the FIVSF there were no significant differences between height of CM during the performance of the element, all values were almost similar (table 2).
The biggest advantage of biomechanical analysis is the improvement of gymnast's performance. One of the important factor evaluated by judges is the fluency of the illusions. Figure 4 represents comparison of both illusions. While entering the illusion there are no mistake in fluency either FIVS or FIFVS. However, at end of the 1st phase (finishing the "illusion part") mistakes in balance could be seen and continuously detected in the 2nd phase as well.
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formed without a mistake. Figure 5 shows the error in the body posture. Another major mistake can be seen while transferring from the 1st to the 2nd phase: gymnast's trunk is moving faster than the leg causing closed angle between the leading leg and torso (Fig. 6).
Serious errors in technique could be detect also in FIFVS. Figure 7 demonstrates incorrect body posture (similar to FIVS) of the 1st phase, as rigid body is required. Due to insufficient range between the legs - 161.31° in the free vertical split (Fig. 8), minimum requirement for the difficulty value (of at least 170°) has not been accomplished as well. Additionally, a small mistake in the position of standing leg, which must be perpendicular to the floor in the vertical split, was detected in both elements (FIVS = 83.04°; FIFVS = 77.58°).
t
Figure 5. Error in the first part of FIVS
Table 2. Height of the CM
CM height [m]
FIVS FIFVS
Starting position 0.94 0.94
1st phase Part 1 0.65 0.65
Part 2 0.98 0.97
2nd phase Part 1 0.61 0.61
Part 2 0.92 0.91
Figure 4. Trajectory of the CM
Figure 6. Errors in transfer from 1st to 2nd phase Based on the results of our investigation we were in FIVS able to analyze errors in technique that occurred while performing both elements. All minimum requirements were met in FIVS, however the element was not per-
Figure 7. Incorrect body posture in FIFVS.
Figure 8. Insufficient range between the legs.
Conclusions. The present study evaluates the kinematic characteristics of two types of difficulty elements in AG with the aspect of correct technique. The kinematic analysis demonstrates that the illusions possess all the characteristics of body rotation dynamics and flexibility as fundamentals. Despite the limitation of this case study the investigation helped to ease the identification of the key phases, movement of the limbs and the CM, resulting in elimination of the errors and further improvement of gymnasts technical preparation.
Aknowledgment
Special thanks are given to the gymnast and members of the technical staff. The study was supported
by the project of Ministry of Education, Science, Research and Sport of the Slovak Republic - VEGA 1/0754/20 & VEGA 1/0089/20.
References
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