BIOMECHANICAL ANALYSIS OF CLEAR HIP CIRCLE TO HANDSTAND ON LOW BAR OF UNEVEN BARS – JUNIOR FEMALE GYMNASTS AGED 12 TO 14

93 Резюме. Ідентифіковані елементи спортивної техніки оберта назад у стійку на руках на нижній жердині. У фазі підготовчих рухових дій під час виконання оберта назад в стійку на руках на нижній жердині виокремлено і досліджено ключовий елемент спортивної техніки «пускова поза тіла» – керована втрата рівноваги тіла назад із стійки на руках; у фазі заключних рухових дій – завершальна поза тіла – стійке положення у стійці на руках. Ключові слова: біомеханіка, гімнастика, бруси різної висоти, ключовий елемент, оберт назад в упорі.

and methods taken from other fields of knowledge (pedagogical, mechanical, physiological, psychologi cal, medical ones, etc.), mainly intended to high light the features of movement on various apparatus by selecting the means of data recording, processing and analysis [15]. Numerous studies and researches are applied for the scientific understanding and clas sification based on the clear establishment of move ments study field in terms of biomechanics. The current guidelines in the specific biomechanical re search of this sports branch and the interest shown in rotation biomechanics are presented as lines of re search on the establishment on the most important characteristics of gymnastics exercises and of compe tition events [6].
Due to the impetuous dynamics of gymnastics competition, the number of technical elements cre ated by the great male and female champions has in creased considerably, some of them taking over, be sides their coded names reflecting their biomechani cal features, the name of those who have created and executed them with a unique virtuosity (for exam ple, the elements «Endo», «Tsukahara», «Comane ci», «Korbut» etc.) [10].
Research and practice show that the efficiency of learning the complex gymnastics elements is in creased if during the process of technical training one check up the phasic structure of elements. In line with these ones, in the technical structure of gymnastics routine can be found out the periods of movement with or without support [2,166]. Sever al criteria can be used for splitting gymnastics el ements into parts, such as pedagogical, psycholog ical, physiological, biomechanical criteria etc. The increase of objectification level goes from the ped agogical criteria towards the biomechanical ones. That is why the biomechanical criteria are used for dividing the gymnastics elements into parts. Thus, the technical structure of gymnastics elements con tains three levelsperiods, stages and phases [13].
Uneven bars, women's artistic gymnastics event, enriched its content with new procedures, in addi tion to the specific trials, whose name is not yet found in the specialized publications. The main di rections of development on this apparatus are the following [9,19]: derivation that is based on trans fer of capacity; composition, namely two procedures merged into a single one characterized by conti nuity; concentration that resides in the increase of the number of complex procedures on bars, releas es and regrasps; loan refers to a critical taking over and integration of procedures from boys to girls and vice versa (more rarely).
Clear hip circle is an element of higher tech nique, of great methodical value, almost irreplace able in competition routines, but especially a ba sic one for acquiring different, difficult, spectacular, dynamic and modern variants. This element itself presents a high difficulty level, since it must be ap proached rather early, on a still weak field of techni cal training and as motor knowledge, due to the ac curacy and intensity of basic actions, to spatial ori entation and even to courage [3].
The review of specialized literature certifies about the importance of the research on gymnastics exercises technique and its learning, taking into ac counts the body postures and positions. In connec tion with this fact, V.N. Boloban and E.V. Biriuk (1979) propose the use of the movement postural ori entation method for studying the technique of gym nastics sports branches [4]. The concept and metho dology of using this method by studying the papers have been perfected during the recent years [1, 4, 5, 12, 16, 17 etc.].
The works has been fulfilled as per combined plan of scientific & research works in sphere of phys ical culture and sports of Ukraine for 2011-2015. Code of topic -2.15. Name of topic: «Control of staticdynamic stability of sportsman's body, sys tems of bodies in kinds of sports with complex coor dination structure of movement» ( state registration N 0111U001726).
The purpose of the paper is the biomechanical analysis of the clear hip circle to handstand on the low bar of uneven bars in the case of junior gym nasts aged 12 to 14.
Work hypothesis assumes that the performance of the biomechanical analysis of clear hip circle on uneven bars, by highlighting the key elements and the mistakes of technical execution, will lead to the ascertainment of training level and to the proposal of some methodological guidelines meant to improve the technical execution on this apparatus.
Methods. This scientific approach led to the or ganization of an ascertaining experimental study within the juniors' team of Deva, applied to a group of 7 female gymnasts, 12 to 14 years old, finalists on this apparatus. The study was conducted during the National Masters Championships, Onești, 16-18.XI.2012. The research used the method of bibli ographic study, the video computerized method by means of Physics ToolKit program; the method of graphical representation -Excel and the «KyPlot» statisticalmathematical processing. Recording was done with a Panasonic video camera of 50 Hz and a capture card with Pinnacle studio 9 software. The biomechanical analysis was performed using the off line markersfree program called Physics ToolKit Version 6.0, which can quantitatively describe, by means of kinematic and dynamic features, the ro tation trajectory of the pairs shoulder hip and of  Results. In table 2 ( fig. 1-3) are shown the re sults of the mean of body segments trajectories at clear hip circle to handstand on the low bar of un even bars, executed by 7 finalist gymnasts on this apparatus, highlighting the duration of the move ment per frames and the key elements (KE) of sport technique in accordance with the momentum of low vertical, the horizontal of movement descending and ascending phase (MP1, MP2, MP3) and the con cluding body posture (CP) -stable position in the handstand.
In figure 3 and 4 are shown the values of the mean of force and angular speed of body segments (G.C.G., Toes and Shoulders joint) at clear hip cir cle to handstand on the low bar of uneven bars.
In table 3 are shown the results of the perfor mances achieved by gymnasts on uneven bars at the    The results of body segments trajectories mean listed in table no. 2 highlight the following charac teristics: movement duration is 0,667 sec calculated at 3 steps of frames moving forward; the structure of key elements of clear hip circle technique present at SP from handstand in the momentum of the horizon tal of descending phase between SJ and T. is at the interval of 0,2 sec; the momentum of the low verti cal is at the interval of 0,4 sec while the momentum of passage from hanging position into handstand and the moment of entering into CP is at 0,467 sec.
Regarding the resultant of the force of the ana lyzed body segments mean, we notice that force val ue at the LP momentum is 1197,65 N at T.(toes), afterwards the force increases at the moment of the descending phase horizontal up to 3276,28 N; before the momentum of low vertical, the force increases up to 17281,67 N at the shoulder, after that the val ue decreases up to 9285 N in the ascending phase, at the horizontal moment; in the end of the movement, the force increases to 3193,33 N ( fig. 3).
In terms of average angular speed of body seg ments analyzed according to the key elements of clear hip circle technique, one can say that at SP momen tum the angular speed is higher at T.(toes), namely -1,65 rad/sec.; at the momentum of the descending phase horizontal the speed is -15,06 rad/sec and be fore the momentum of low vertical the angular speed increases at SJ up to -27,86 rad/sec; afterwards,   during ascending phase, at the momentum of hori zontal passage from hanging position into handstand, the higher speed is in (SJ) shoulders joint and GCG, approximately -16-18 rad/sec.; to the end of the movement, the angular speeds are equal, reaching -1,65-3,21 rad/sec ( figure 4). As for the competition results achieved by the subjects of the study, one can point out that all the 7 gymnasts participated in the finals, excepting the 7 th rank; as for the results of assessment of routines by the judges, one can highlight a mean of 4,77 points of the score for routines difficulty; 8,42 points for the execution score and 13,18 points for final score; the score for apparatus finals is 12,61 points, lower than in the allaround competition (table 3).
Conclusions. The biomechanical indicators re quired by the video computerized analysis used in this research show the number of studied cases, gym nasts' weight and size in handstand position; there are also shown the characteristics of the rotational movement around a fixed point on the apparatus in terms of rotational inertia and radius of movement of the analyzed body segments.
The results of the mean of body segments trajec tories highlight the duration of the movement cal culated at 3 steps of frames moving forward; the structure of the key elements of clear hip circle as for launching body posture from handstand position, the horizontal momentum of the descending phase between shoulders joint and Toes; momentum of low vertical and momentum of passage from hanging po sition to handstand position for entering into con cluding body posture.
The resultant of the average force and angular speed of the analyzed body segments emphasize their influence upon the technical execution in different moments of the movement.
The biomechanical analysis of the key elements highlights some mistakes in the execution of key ele ments of the clear hip circle to handstand technique, in terms of body start position, multiplication of po sition and final position of coming back into hand stand. These observations may serve us for future research that will aim to develop linear branched learning algorithmic programs for each key element of women's artistic gymnastics sports technique.
The biomechanical analysis of clear hip circle to handstand on uneven bars by emphasizing the key elements and the technical execution mistakes has led to the ascertainment of technical training lev el and to the proposal of methodological guidelines for improving the technical execution on this ap paratus.