Jump Shot In Handball

Jump Shot In Handball The jump shot is one of the most important elements of handball as in the game, motor behavior are performed in specific conditions with the presence of players of the opposing team and while adhering to the regulations. However which areas can be controlled and are used to make the handball action more efficient? Thus we will look into the jump shot in which handball is analyzed in its different phases to find out its efficiency. The goals of the run, jump, shoot are ball velocity and accuracy. Maximum ball velocity and precision is required to minimize the chance of the opponent or goal keeper intercepting the shot. In team handball, shooting to score goals is one of the most important aspects of the game. In order for a shot to be successful, it must have maximum ball velocity and precision for an element of surprise for the goalkeeper (Wagner Muller, 2008). Wagner, Buchecker, Duvillard, and Mulller (2010) state that 67% of ball velocity at ball release was explained by the summation effects from the velocity of elbow extension and internal rotation of the shoulder. Thus we divide them into Approach, Take-off, Shoot, Land. Logically speaking, the faster the ball is thrown at the goal the goalkeeper will have a lesser time to save the shot. In order for a throw to be successful, the highest velocity at ball release together with aiming accuracy is required therefore during the game, thus the athlete has to keep up with the optimal efficiency of these two factors (Zapartidis, Gouvali, Bayios, Boudolos, 2007). Accuracy is something defined as variable. We didnt want to make it become a close-system where the subject keeps hitting at the same spot. Thus in the analyzing performance stage, we came out with a table to judge the subject throwing effectiveness in performing the skill. Zapartidis, Toganidis, Vareltzis, Christodoulidis, Kororos, and Skoufas (2009) reported that players during the game are notably affected by time as aiming accuracy or ball velocity gradually decrease. In all sports tasks, most coaches apply eight biomechanical principles when analyzing their athletes (Bartlett, 2007). These eight principles can be separated into two broad categories. The 3 basic universal principles; use of the stretch-shortening cycle, minimization of energy used, control degrees of freedom. The other 5 general principles; sequential action of muscles, minimization of inertia, impulse generation, maximizing the acceleration path, stability. These apply to sports tasks which are usually used by speed generation. However not all of the principles can be used to apply in every sport. For example, the stability is a one of the biomechanical principle which is applicable to sumo wrestling. Whereas it is not applicable in the game of handball, as there is a lesser emphasis on having a wide base of support for stability when preparing for a shot (Knudson, 2007). In handball, the biomechanical principles that can be applied are use of the stretch-shortening cycle, minimization of energy used, control degrees of freedom, sequential action of muscles, minimization of inertia, impulse generation and maximizing the acceleration path. The recruitment of each part of the body is important by allowing the development of maximal velocity of these parts. This begins from the proximal parts then to the distal parts of the body. The larger proximal joint starts the action by accelerating, thus a transfer of momentum results in a high velocity to the smaller distal joints. Each segments of the kinetic chain is linked to the stoppage of the proximal part results in the increase of angular velocity (Pori, Bon, Sibila, 2005). When performing the shot, certain physiological characteristics are taken into considerations. Therefore, at least for some muscular groups there should be the shortest possible time between extension and contraction for muscles involved in this phase (Pori et al., 2005). Pori et al. (2005) concluded that better players make use of extensors in the wrist better than worse players. Components of Skill 1. Approach (Run-up) Physique We assume there will be significant differences to the speed of ball release in our goal of skill regarding to body height and body weight between handball players of different performance levels (Hasan, Reilly, Cable, Ramadan, 2007). Are tall athletes better than shorter ones? Thus we have physique. Taller handball players with greater body weight have the ability to achieve a higher ball release speed (Wagner et al., 2010). Maximizing acceleration path is a critical factor Using the work-energy relationship which shows that a moving object is equals to work done. This is important for the handballer maximizing use of the run-up which to apply force (Bartlett, 2007). Using the formula: Velocity/Time Acceleration for an increase in velocity, acceleration also increases. 2. Take-off Contact Maximize force generation is a critical factor This is where the Angle, Speed, Height of Jump comes. Further increase in speed at take-off is required by generating more impulse just at take-off. Using the impulse-momentum relationship where change of momentum, I=Ft, increased in I= increased Force exerted on the ground multiply by increased Time of force. From an increased in F we have F=Mass of the athlete multiply by increasing Acceleration of the athlete. This movement requires being fast and powerful at take-off. 4. Shoot Sequence of trunk joint and muscle group in throw Ball velocity at ball release was explained by the summation effects from order of the proximal parts to the distal parts of the body (Wagner et al., 2010). High release point is a critical factor A high elbow release point needed to generate much velocity. The time of the take-off contact would point to fast and elastic strength of the subject and indirectly affect the height of a throw and ball velocity. 5. Land Contact with the ground is a critical factor Decreased force over a period of time by bending knees when landing to reduce the mean impact force which also can prevent further injury. Deterministic Model Run, Jump, Shoot Figure 1 Important considerations for videotaping the skill The points below have been well thought-out to minimize errors recorded during two-dimensional filming, thus improving the accuracy of all data (Bartlett, 2007). Perspective and parallax errors were paid carefully attention to. 1) Position of camera The camera is mounted on a fixed tripod, on a level ground and aiming at the subject. The camera is positioned as far away from the action in order to reduce perspective error. The field of view (FOV) is adjusted to match with the performance of the subjects which as is recorded. As this take advantage of the performer on the projected image and increases the accuracy of digitizing. Once the FOV is in place and it is kept constant at all time. The camera is placed perpendicular to capture the movement of the subjects, horizontal scale of 7m and vertical reference from the goal post. The set-up is shown below, Figure 2. Figure 2 A line was marked out 7 meters from the goalpost and subject use the take off area as point of jump. The camera was place 10 meters perpendicular to the take off area. 2) Lighting Filming is done outdoors, a location with a dull and non-reflective background was use to allow the athlete and the ball to standout. This will make it easier to assess the movement patterns and biomechanics of the jump shot. In contrast, if the background or backdrop was to be too bright, the athlete would be hard to spot. 3) Background The background is as neat as possible, simple and non-reflective as it provides a good contrast which allows the viewing and estimating of the axes of rotation from the subjects anatomical landmarks. 4) Shutter Speed A shutter speed of 1/2000 was selected as this shutter speed would allow for slow motion playback and ease the motion analysis process. Using a lower shutter speed would cause blurriness when the video is playback, while a higher shutter speed comes with a decrease in image quality, thus making analysis impossible. 5) Subject Preparation The recording of the movement is as unpretentious as possible. The subject is briefed that he is performing in front of a camera in an experimental perspective and had little clothing to minimize errors in locating body landmarks. A verbal consent is obtained from the athlete participating in the analysis. The subject was told to throw the ball as fast as possible into the net for the initial 4 shots. After which, he was given coaching cues to correct his technique and delivery of the skill. Results of the Videotaping Session The male subject is a national basketball player who trains 5 times a week (Height-189 cm; body mass 82kg; age 24 years old). He does not have prior experience to playing handball therefore is a suitable candidate. In order to evaluate the over arm throwing performance, according to the International Handball Federation, (IHF), rules of the game a standard handball was used: (Circumference 58-60cm and Weight 425-475g, IHF Size 3, for Men and Male Youth (over age 16). The subject was told to throw as fast as possible; no coaching cues were given for the first 4 shots. Therefore we came up an evaluation of the quality of the execution skill for the subject in Table 3. Table 3 Mark Run-up Take-Off Shoot Land 3 Optimal speed of stride and synchronized lowering of CG, Execution is smooth, in cadenced Planting of takeoff leg accurately, take-off is vertical, explosiveness The elbow is high and moving along height of the head, correct use of sequential muscle groups into the throw, explosive finishing Land on take-off leg or on both legs simultaneously with knees bend 2 Fairly too short or too long stride, Execution still fluent, in cadenced Placement of takeoff leg rather far from the goal, take-off going a little too forward The elbow still moving low, technique of execution better Average execution, with slight unbalance 1 Lack of speed, hasty lowering of CG, not in cadenced, poor execution, execution is poor Placement of takeoff leg is too far from the goal, take-off oriented too forward, lack of explosiveness Placement of takeoff leg is significantly away from the goal, take-off directed markedly forward Land on non-take- off leg, poor execution Legend: CG centre of gravity; Mark: 1 Poor, 2 Average, 3 Good As for the first 4 jumps shots, the subject attainted 10.6  ± 0.2 m/sec for the ball velocity at release. The following are the results of the first 4 jump shots, Table 4. Table 4 Attempt Run-up Take-Off Shoot Land Total Score 1 2 1 1 1 5 2 1 2 1 2 6 3 2 1 2 1 6 4 2 1 3 1 7 Attempts to give too many cues to the subject will paralyze the subject. After letting him explore the jump shot on the initial 4 shots, this time the subject was then told to aim for the top right hand corner of the goalpost, using the jump shot technique. We gave him coaching cues to correct his technique starting from the run-up phrase, take-off, shoot and then leading to landing phrase, Table 5. Table 5 Critical Features Coaching Cues Run-up Take a long third step Take-off Explosiveness-gain vertical height Optimize height of release Release at the top Angle of release Draw a semi circle Summation of forces Smooth-jump and shoot Rotation of ball Flip wrist Land Bend knees The following are the results of the jump shots with coaching cues given to him in Table 6. The subject attainted an improved 12.6  ± 0.4 m/sec for the ball velocity at release. Table 6 Attempt Run-up Take-Off Shoot Land Total Score 5 2 2 3 1 8 6 3 3 2 2 10 7 2 3 2 2 9 8 3 3 3 3 12 Qualitatively analysis Evaluation of performance After taking the video for the running jump shot, we compare it to a elite athlete jump shot. There are a few features which are important in the sequence, the run up (3 steps), the jump and the throw. The run up The 3 steps run up will provide the athlete impulse for the jump shot. As impulse = change in momentum (Blazevich, 2007). F.t = m.v m.u Momentum is the quantity of motion possessed by the body. Therefore a run up is important in this aspect. After assessment, we found out that the subject did a 1 step run up which did not create enough impulse. Therefore the rating is poor -good for the run up Critical Features Rating The run up Poor 1 step run up The jump The height of the jump is determined by a few factors, the weight of the athlete and the acceleration. F = ma The reason for the bending of the knees for a higher jump is that the time it takes for the athletes to leave the floor (Muller, 2009). v = u + at Vavg = s/t Presume the jump height is the same, the less time, he takes to jump the same distance, the more velocity the person create, the higher the person will go. By contracting the quadriceps, will stretch the tendon, by doing this, it is possible to jump higher. The assessment for the subject is poor-good as he did not bend his knee, and straighten his leg after that. Critical Feature Rating Bend Knees Poor-Good Straighten leg Poor Bend Knee? Straighten leg? The throw The speed of the throw is determined by the speed difference and the time it take for the ball to leave the hand. It is similar to the theory of the jump, where the more distance and less time you take the faster the ball will travel. The difference is that there is a twist to the body; therefore there is an angular motion to it. ÃŽÂ ±= (à Ã¢â‚¬ °f à Ã¢â‚¬ °f)/t à Ã¢â‚¬ ° = Ó ¨/t Since the mass of the ball is the constant. The only factor that can influence the amount of force being exacted on it is acceleration. T = I ÃŽÂ ± (angular) Critical Features Rating The pull back Poor Good The follow through Poor Good Pull back? Follow through Correcting the performance The whole sequence of the running throw will be broken to parts to teach the subject. Critical Features Rating Picture Remarks / Strategies Coaching Cues The run up Poor The run up will be done in 3 steps, the subject will attempt to take 3 wide steps to gain speed. Wide Step; More Force Bend Knees Poor Good The subject will jump on the spot, with the knees bend before the jump. Squat more Straighten leg Poor The subject will jump and straighten the leg to gain more height. Explode; Stretch The pull back Poor Good The subject will try to shoot with the jump. By pulling the arm further back. Arc back; Roll Shoulder The follow through Poor Good With the pull back, the subject will attempt the follow through with the same action. Follow through; Swing arm Discussion There are mainly two factors in shooting technique of handball, the first is speed ball velocity of shoot, and the second factor is that no clear prediction of direction to shoot for goal keeper. This approach gives a good evaluation on the kinematic structure in analyzing handball. Thus, this model can be used in detecting the efficiency of the jump shot. An examination of individuals information and its comparison with the model allow us to identify weakness in the execution of jump shot. The use of biomechanical analysis maybe helpful in correcting or perfecting techniques, however the efficiency of the player in a game does not depend solely on performing a perfect kinematics structure during an isolated testing environment.