EVALUATION OF THE KINEMATIC STRUCTURE OF INDICATORS KEY ELEMENTS OF SPORTS

Annotation. Purpose: Examine the kinematic structure of indicators key elements of sports equipment exercise (difficult to coordinate). The method of postural orientation movements. Material: The study involved acrobats jumpers on the path of high qualification (n = 7). The method used video computer recording the movements of the athlete. Results: Identified nodal elements of sports equipment double back somersault tuck. Exercise performed after rondat and double back flip and stretch after rondat flick (coup ago). In the preparatory phase of motor actions acrobatic exercises isolated and studied central element of sports equipment starting posture of the body; in the phase of the main motor action animation poses of the body; in the final phase the final body posture (stable landing). Conclusions: The method of video computer registration allowed to perform a biomechanical analysis and evaluation of key elements of sports equipment double back somersault tuck and a double back flip and stretch. Also gain new knowledge about the mechanism of the phase structure of movements when performing double somersaults.

practice other kinds of sports with complex coordination of movements (free style, jumping in water, jumping on trampoline and other). So, practical recommendations for mastering of exercises' technical structure are demanded. Back double somersault in group position, double back arching somersault -are exercises of high difficulty. Considering multi-functional purpose of the mentioned exercises (fulfillment with stoppage, transferring to combination of exercises; making this exercise more difficult in vertical direction, for example, triple back somersault in group position, triple back arching somersault) the role of technically correct body positions on rest for effective pushing off for somersault increases. Analysis of sportsmen's performances shows that most mistakes in fulfillment of somersaults were registered in pushing offs and landing [15].
Thus, method of movements' postural orient as mean of bio-mechanical study of sport exercises with the help of analyzing of preceding and following body postures, body positions in phase structure of fulfilled exercise is realized in sport science for learning of sport technique's key elements [3 -7, 11-14].
The work has been fulfilled in compliance with "Combined plan of SRW in field of physical culture and sports of Ukraine for 2011-2015" by topic 2.15 "Control of static-dynamic body balance by sportsman and system of bodies in kinds of sports with complex coordination of movements" and by governmentally financed topic "Technical training of qualified sportsmen on the base of simulation of sport exercises' motion structure".
Purpose, tasks of the work, material and methods The purpose of the work -is to study kinematic structure of indicators of sport technique's key elements, of exercises with complex coordination of movements with the help of method of movements' postural orient; to identify key elements in phase structure of exercises (on example of back grouped double somersault after rondat and arching back double somersault after rondat -back turnover. The method and organization of the research: video-recording of acrobatic exercises (with two digital cameras of 240 shots per second speed. Application of computer program APAS 2000 for receiving of quantitative data about bio-mechanical structure of the analyzed movements. In our research highly qualified acrobats-jumpers on track (п=7) participated. Mean indicators of body height, body mass and acrobats' age (х±S) were as follows: 170. 00±4. 00 cm, 72. 40±3.60 kg, 20. 40±1. 70 years old.

Results of research and their discussion
In preparatory phase of the analyzed somersaults we marked out starting position of body(SP) as sport technique's key element -bio-mechanically rational position of sportsman's body in coordinates' system, on floor, which creates effective conditions for pushing off and controlled upward flight; in phase of main movements -sport technique's key element is multiplication of sportsman body's postures (MP). Multiplication of sportsman body's postures is a process of consequent alternation of instant, fixed postures for creation of holistic movement; these postures determine and characterize content of exercise; in final phase -sport technique's key element was final posture of body (FP) -landing and stoppage.
Phase of preparatory actions. Indicators of angle joints (see fig.1) are as follows: the tested A (variant 1) had angle thigh -torso 177. 0°, the tested B (variant 2) had angle thigh -torso 184. 4°. In variant 1 sportsman keeps body posture rigidly; he interacts with support, he effectively use energy of elastic deformation. It is proved by scientific fact that resultant curves of speed of sportsman A body's bio links are bunched ((see fig.2), time 0.633 sec.) during short term fixing of starting body posture on support. In variant 2, sportsman B shows excessive plasticity of body position in short term fixing of SP with arms upward and slightly backward. It facilitates arching of body. Certain loss of energy during short term fixing of SP happened; rigidness of "sportsman-track" system was also lost and, finally, resultants of speed of body bio-links were not bunched (see fig.2, time, 0.583sec.).    Phase of final movements. In fig. 7 we present body postures of final phase, which go just before key element -FP (balanced landing), (variant 1 -1. 750 sec., variant 2 -1. 683 sec.). In variant 1 hip-torso angle is 144.63°, in variant 2 -141.93°. Video analysis, pedagogic observations permit to conclude that in variants 1 and 2 sportsmen demonstrate elastic-rigid interaction with support, which facilitated taking optimal FP -"half squatting" with "half bending" of body, arms forward-downward and effective control of body posture on support..

Conclusions
In phase structure of acrobatic jumps on track (grouped back double somersault after rondat and arched back double somersault after rondat -back turnover) we, with the help of movements' posture orient method, indentified key elements of sport technique. We found that key element of sport technique is a signal posture of movement, which predetermines effective following actions in certain exercise.
We have proved that signal postures of the studied by us sport exercises were: starting posture of body (biomechanically rational posture of body on support for effective upward flight in somersault), multiplication of body postures (consequent alternation of instant, fixed postures fro creation of holistic movement), final posture of body (landing and stoppage).
Solution of tasks of acrobatic exercises' bio-mechanical analysis and working out of up-to-date training programs will permit to realize significant reserves of training process, improve theory and practice of all kinds of sports, which are characterized by complex coordination of movements.