Dr.Med, Professor L.V. Kapilevich¹
Ph.D. E.V. Koshel'skaya²
Postgraduate student A.V. Razuvanova^2
1National Research Tomsk State University, Tomsk
²National Research Tomsk Polytechnic University, Tomsk

Keywords: jump shot, coordination, basketball, motion tracking

Introduction. It is a matter of common knowledge that modern basketball is the sport that requires complex highly coordinated motor skills with an ample variety of active movements both on the playground and in the air. When highly skilled basketball master soars in the air for the shot or makes dribble drive to slip through the defense, the movement sequences are often as complicated and smooth as ballet steps. It is the shots to the ring from different distances that comprise an objective and a key element of any aerial (unsupported) position in basketball [5]. There is a great variety of such shots, with around 70% of them being performed in the game by one hand overhead in a jump (a jump shot) [3]. Jump shot perfecting practice is always rated among the top priorities of any training process by both basketball professionals and newcomers to the sport (including school and university students), and skillful jump shooting technique may heavily contribute to the player’s mental fitness, game success and the further educational process [1].

At the same time, sport physiology science qualifies the unsupported game position as a non-standard situation for any motor action [2, 4] and confirms that adaptation of the body to such movement sequences requires its functional systems being readjusted through complicated and multisided process.

The purpose of the study was to explore the specifics of the jump shot biomechanics depending on the skill levels of basketball players acting in the unsupported positions.

Materials and methods. 20 young men of 18 to 25 years of age that were broken down into two equal groups of 10 people were subject to the study. Main group included fairly skilled basketball players rated at least with Class 1 Seniors. Control group included 10 students qualified for basic physical education course based on the medical examination. Both of the groups were required to perform the same action that was the jump shot to the ring from the free-throw line, i.e. from 4.2 m distance.

Motion tracking method – meaning the frame-by-frame video capture of the movement sequence by a high-speed digital camera – was used to collect biomechanical data for the analysis. We used Vision Research Phantom Mire X2 video camera for the purposes of the study, with the video shooting rate set at 200 frames per second. StarTraceTracker 1.1 VideoMotion® software was applied to make the video data analysis with data processing and graphic presentations.

Results and discussion. The study was designed to profile only the active phase of the movement sequence. The active phase of a jump shot includes the elbow being extended towards the target with a simultaneous take-off movement by the both legs pushing away from the support with extension of the knee joints and hip joints. Then the body goes to the aerial position, extends and stretches up to the full vertical position and, when the top point is reached, the ball is thrown to the target.

Our video data analysis and graphic presentations detected some differences in the active phase performance sequence by both of the groups. One of the main differences was registered at the ball throwing moment. The main group players were found to throw the ball in the topmost point of the jump. Every main group diagram shows that the ball release point is fixed on the dotted line along the axis Х = 0.57 s; whilst the head movement tracking diagram (Figure 1, А) shows that it is the moment when the vertical travel curve reaches its peak at Y = 2.33 m.

The picture is totally different for the control group. First, the ball release moment comes well before the feet take-off moment that means that the player first throws the ball and then jumps. The ball release point is found along the axis Х = 0.46-0.47 s, and the aerial position timeframe is Х = 0.48-0.65 s (Figure 2). Therefore, it is quite obvious from the study that the control group players reach the top point of the jump without the ball, i.e. the jump is inactive in fact (Figure 1, B, head movement diagrams), with Y = 2.55 m and Х = 0.54 s. This typical error of the control group players is indicative of the poor timing and coordination of the movements prior to the jump; and this may mean that they feel awkward and perplexed on the verge of the unsupported position and this emotional disarray is of negative effect on their motor skill performance ability. Their movement control is focused on the jump as a dominating element that means that the jump is made for jumping, in contrast to the main group performance that is focused on the jump for shooting.

In the second part of the study we analyzed the extension-flexion dynamics of the anatomic angles in two groups. The anatomic angle formed by the pelvis-shoulder-head curve (Angle 1), for instance, is characteristic of the body positions vs. the vertical line. For the main group athletes, Angle 1 at the take-off moment is close to 150° (Figure 3, А), and thereafter the angle smoothly bends down to reach 120° at the ball release moment followed by some extension when nearing the landing point with Angle 1 coming to 140° when the feet touch the ground.

For the control group athletes, Angle 1 varies within the range of 100° to 120° during the jump sequence (Figure 3, B). Making the relatively low jump, the control group athletes are always more bent in the thoracic spine segment. Their movement sequence is absolutely uneven as the angle variation dynamics of the extension-bending sequence is never smooth in the aerial position, with strong fluctuations in this body segment. To put it in other words, even if the ball was released in the topmost point of the jump sequence, the shot accuracy would never be high for the reason that the fluctuations of the vertical axis of the body would give no chance for a precise shot. It may be interesting to note that the control group athletes in aerial position normally simulate the ball release action without the ball as demonstrated by the elbow angle dynamics for the throwing hand (Figure 3, B).

Angle 2 formed by the pelvis-shoulder-elbow curve is found to make up 80° at the start of the jump by the main group athletes. Thereafter it smoothly increases up to 130° (Figure 3, A), then goes the throw, and after that Angle 2 stays in the extended position all the way through till the landing moment. The control group Angle 2 dynamics (Figure 3, B) is different since Angle 2 at the start of the jump comes to 130° as if the throw was already completed and stays virtually the same all the way through till the landing moment.

Conclusion. Findings of the study are indicative of the fact that the control group athletes – even when they are skilled enough to throw ball from spot and perform high jumps – are unable to perform simple motor skills when it comes to an unsupported aerial position. Highly skilled basketball players realign the movement sequences so as to effectively adapt to the aerial position and secure the movements being duly coordinated in the air and the body soaring phase being mastered and turned to a technical skill. It should be mentioned at the same time that the physiological adjustment of the body systems to the unsupported positions of the jump shots may be considered a factor of generally negative effect on the success rate of the relevant motor actions.

Figure 1. Head movement diagram in unsupported body positions: main group (А) versus control group (B)

Figure 2. Wrist movement diagram in unsupported body positions: main group (А) versus control group (B)

Figure 3. Extension-flexion dynamics of anatomic angles in unsupported body positions: main group (А) versus control group (B)

References

1. Zagrevskiy, V.I. Komp'yuterny sintez dvigatel'nykh deystviy s upravleniem dvizheniem po kinematicheskomu sostoyaniyu biomekhanicheskoy sistemy (Computer synthesis of motor actions with movement control based on kinematic state of biomechanical system) / V.I. Zagrevskiy, O.I. Zagrevskiy // Teoriya i praktika fiz. kul'tury. – 2013. – № 7. – P. 10–15.
2. Kapilevich, L.V. Fiziologicheskiy kontrol' tekhnicheskoy podgotovki sportsmenov (Physiological control of athletes' technical training) / L.V. Kapilevich // Teoriya i praktika fiz. kul'tury. – 2010. – № 11. – P. 12–15.
3. Pritykin, V.N. Opredelenie optimal'nykh traektoriy poleta myacha i kharakteristik tseli v basketbole pri broskakh po kol'tsu so srednikh i dal'nikh distantsiy (Optimal ball flight trajectory and target characteristics in basketball at hoop shots from medium and long distances) / V.N. Pritykin, V.A. Lesukov, A.A. Geraskin, A.V. Rodionov // Teoriya i praktika fiz. kul'tury. – 1996. – № 10. Electronic resource. Available at: http://lib.sportedu.ru/Press/TPFK/1996N10/p48-54.htm (Date of access 17.01.2015)
4. Koshel'skaya, E.V. Upravlenie sportsmenami polozheniem tela v prostranstve v faze poleta (Athlete's body position control in aireal phase) / E.V. Koshel'skaya, A.V. Razuvanova, O.S. Smerdova et al. // Teoriya i praktika fiz. kul'tury, 2014, №12, P. 47-49.
5. Sportivnye igry: Tekhnika, taktika, metodika obucheniya: uchebnik dlya stud. vyssh. ped. ucheb. zavedeniy (Team games: Technique, tactics, training technique: textbook for students of higher. ped. ed. institutions) / Yu.D. Zheleznyak, Yu.M. Portnov, V.P. Savin, A.V. Leksakov; Ed. by Yu.D. Zheleznyak, Yu.M. Portnov. – 2nd ed., stereot. – Moscow: Akademiya, 2004. – 520 P. Electronic resource. Available at: http://fizkult-ura.ru/sci/basketball/24 (Date of access 17.01.2015)

Corresponding author: kapil@yandex.ru