Accuracy and Velocity of the Elite Female Turkish Handball Players

Transcription

1 International Journal of Sports Science 2014, 4(1): DOI: /j.sports Accuracy and Velocity of the Elite Female Turkish Handball Players Zeynep Inci Karadenizli 1,*, Habibe Serap Inal 2, Bergün Meriç 3, Menşure Aydın 3, Çiğdem Bulgan 4 1 Marmara University, School of Physical Education and Sports, Anadolu Hisari, Istanbul, Turkey 2 Yeditepe University, Faculty of Health Sciences, Physiotherapy and Rehabilitation Department, Istanbul, Turkey 3 Kocaeli University, School of Physical Education and Sports, Kocaeli, Turkey 4 Halic University, School of Physical Education and Sports, Istanbul, Turkey Abstract We aimed to compare the overarm throwing accuracy of the handball players to the goal with/without the signed target (w/wost) and to assess the role of the trunk and the throwing arm segments. Elite female handball players (N=12) are in the age of ± 2.43 years and have been in the Turkish National Team since they are 12.0 ± 2.2 years, were participated to this study. In this study, he segmental angular and linear velocities of their trunk and the throwing arm, with the speed of the ball were examined. The maximum speed of the ball to the goal was 85 kmh -1 during wst and 88kmh -1 wost. The decrease in the angular velocity of the internal rotation (55%) and the flexion (66%) of the upper arm segment was significant in favour of the goal wst (p < 0.01). The angular velocity of shoulder internal rotation and the resultant linear acceleration of the elbow joint during the wost accurate throws were related (p = 0.02). Thus, there is a slowing down in the upper arm segment (flexion and internal rotation) at pre-release to ensure the accuracy of the throws wst. Additionally, internal rotation and extension of the elbow velocity are important for the maximal accurate throws to the target; pelvic rotation is effective on elbow internal rotation at pre-release. Therefore, for the acquired overarm throws, the elbow extension and internal rotation; shoulder internal rotation are important as well as the pelvic rotations of the handball players. Keywords Kinematic, Handball, Overarm Throw, Velocity, Accuracy 1. Introduction Among the kinematic features of overarm handball throwing to the goal, velocity and accuracy are considered as the most important parameters of the performance of players[1,2]. Although the maximum or near maximum throwing velocity is required for scoring[3], the hardest and the fastest throw may not always be the most successful factor[4]. Therefore, a speed-accuracy trade-off exits during performing an overarm throw[3-5]. According to Fitt's Law, both are inversly interrelated each other: as the ball speed increases, the accuracy decreases. The increased difficulty of the throw is another factor that may govern the accuracy; in other words the smaller the target area of a well-defended goal is the longer the distances to target are [2,3,6,7]. Thus, it can be concluded that velocity and accuracy are incompatible and may require different strategies during the execution of the motor task[8]. According to the previous kinematic studies done in this issue, there are interactions concerning many factors * Corresponding author: inci.karadenizli@marmara.edu.tr (Zeynep Inci Karadenizli) Published online at Copyright 2014 Scientific & Academic Publishing. All Rights Reserved determining the ball velocity, which include the technique of motion, upper and lower extremity of muscle strength and power, and timing of the action[9] as well as anthropometric factors[10]. However, for an accurate throw, body segments are expected to exert the sufficient amount of angular velocity[11] and produce a forward acceleration from proximal to distal in favor of the distal segments[12,13]. The throwing arm that conducts the movement and transfers the generated velocity to the ball[12,2,14] determines the segmental angular and linear velocity as well as the acceleration of the joints, and the ball velocity at release[2,15,16]. On the other hand, it was reported that the forward acceleration of the distal segments occur with a non-proximal-to-distal progression in experienced handball players[9,17]. Throwing type is also another feature controlling the velocity of the ball. The most common overarm throws preferred by the players in handball are the vertical jump, on the spot and with the cross over step. The throw with the cross over step is considered as the one with the highest velocity compared to the other types[1,18]. Thus, the throwing velocity composed of the segmental velocities and the ball speed are important factors for the accuracy of the overarm throws in handball. However, as the degree of the difficulty of the task is increased, the

2 22 Zeynep Inci Karadenizli et al.: Accuracy and Velocity of the Elite Female Turkish Handball Players segmental interactions in regard to the velocity and accuracy of the players are becoming important features. Thus, we aimed to examine the segmental angular and linear velocities between trunk, shoulder, elbow and wrist joints during the accurate overarm throws with cross-over step of the players. We also aimed to observe their role in the accuracy of the task. 2. Material and Methods 2.1. Subjects Twelve (12) elite female handball players in the age of ± 2.43 years have been in the Turkish National Team since 8-15 years (12.0 ± 2.2 yrs), and competed internationally 57.0 ± times participated in the study. Dominant side of the players were left side except three of them, and their mean height and weight were ± 3.9 cm and 66.8 ± 8.6 kg, respectively. The inclusion criteria for the study were (a) being female between the ages of years, (b) currently playing in the national team, (c) having no shoulder or elbow injuries that were reported by the team physician. Before the test, players were informed about the test procedures and they consented for the procedures carried out in accordance with the protocol approved by Marmara University Ethical Advisory Committee ( /19). The players were informed about the importance of the procedure to encourage them to get maximum performance. It was explained that the achieved outcomes as a result of their maximum effort and their accuracy in performing the test will exhibit their skills in overarm handball throw with a cross over step. This motivation, however, might be considered as the weak point of our methodology Instruments Three Basler A602f black and white digital cameras were used to capture of the images, which were 100 Hz. and Before the recording, 8 point calibration cage (5600 cm³ rectangular) was placed and captured at the middle of the field for the DLT method to describe the three dimensional coordinates[19] were placed at 90º angles to each other on the field. The six reflector markers reflecting the infra-red lights were placed on both acromions for shoulders, lateral epicondyle for elbow and lateral styloid process for wrist of the throwing arm, and also spina iliaca anterior superior for pelvis. For analyzing kinematic data SIMI 6.2 Motion Analyze System was used. Molten brand leather handballs, each weighted 325 g (No. 2) were placed in the ball case on players non-dominant side. We also used Sports Radar Gun (km.h -1 ) Astro Products, CA to measure the ball velocity, which was positioned 2m behind the players in the throwing area at the 9m line of the field Procedure We let players warm up for 15 minutes of free run and throws just before the test. The test were implemented at two stages that the players were asked to perform basic overarm throws with a cross over step, defined as with three steps and a support step 9 m away from the target within the three seconds[20]. In the first stage, each player was asked to carry out two throws with maximum velocity to the goal as much as possible (throws without a signed target - wost). Then, the four iron square target frames with the dimensions of 60 x 60 cm were placed on each corner of the goal and a randomly controlled light system by the same person who had experience in handball game situations, was hired in the second stage of the test to indicate the target location. The light was on when the player touched the ball in the case besides her. They were asked to throw the ball four times again with their maximum velocity to the singed target frame (throws with the signed target - wst). A 1-2 min rest elapsed between the first and the second stage and s elapsed between the throws were given[1]. The differences between the accurate throws without a singed target and with the signed target regarding to the angles of shoulder, elbow and wrist joints were evaluated. The angular and linear velocities and accelaration of the upper arm and forearm segments, as well as shoulder, elbow and pelvic rotations in horizontal, frontal and sagital planes and related axises as xy, xz, yz, were examined. The highest accurate throws without a signed target (two throws) and with the signed target (four throws), were taken in consideration for the kinematic evaluations. Figure 1. Calibration cage, radar, markers and target frames Figure 2. Views of three camera during the throws

3 International Journal of Sports Science 2014, 4(1): Statistical Analysis The achieved data was analyzed with parametric tests through the Statistical Packages for Social Sciences for Windows. Descriptive analysis was used for measureable values and Wilcoxon Signed Ranks Test was used for significant of the mean differences between the ball speed and the angular, linear and resultant velocities of the segments and the joints. To understand the significance between the throws to the goals without a singed target and with the signed target Two tailed Pearson Correlation Test was used and the significance was considered as 5%. The power analyses of the test were performed to understand the sensitivity of the tests. 3. Results Table 1 reveals that the maximum overhead accurate throwing speed with a cross over step measured by radar was 88 km.h -1 to the goal without singed target and 85 km.h -1 with the signed target (p < 0.01). The accurate overarm throwing with a cross over step was 93.8% of the maximal ball speed. That means the speed of the accurate throw to the signed target was 6.1% less than the ones without a signed target. According to the SIMI Motion Analyze System, the upper-arm segment angular velocity of the athletes showed significant differences in internal rotation and flexion in favor of the acquired goals with signed targets just before the ball releases the hand (pre-release). In other words, athletes had tendency to decrease the angular velocity of their upper-arm segment while throwing the ball to the signed target in the goal to secure the accuracy. Table 2 reveals that these decreases were 66% in internal rotation (horizontal axis-xy) and 55% in flexion (sagital axis-yz) (p < 0.01). We have found a significant relation between the angular velocity of shoulder internal rotation and the resultant linear acceleration of the elbow joint during the accurate throws to the goal without target at pre-release of the ball (r = 0.64, p = 0.02). The resultant velocity of elbow was related with maximal accurate speed of the ball thrown to the goal with signed target at pre-release (85 km.h -1 ) (r = 0.59, p = 0.01). On the other hand, the angular velocity of pelvic rotation and the forearm segment s internal rotation (pronation) velocity to the goal without the signed target were also found related with each other at pre-release (r = 0.59, p = 0.05). Thus, shoulder internal rotation and the elbow velocity is important for the accurate ball throws. Table 3 reveals that we have not found any significant relation between the linear velocities of the joints, however, when we compare the resultant linear velocities of the elbow with shoulder joints, although, it is not statistically significant; there was a decrease in both joints' resultant linear velocities during the throwing to the signed targets, to secure the velocity. These differences were 37% for the shoulder and 10% for the elbow joints. Table 4 reveals that in horizontal axis (xy), the angular velocity of shoulder joint and pelvis rotations presented a decrease while the ball was being thrown to the goal with the singed target. Though this difference was not significant, it presented the idea that during the overarm throwing, the players may have tendency to slow down their arm velocity towards the end of the throw, just before the release of the ball for the favor of the accuracy. Table 1. Post-release ball velocities of the accurate overhead throws with a cross-over step measured by radar Ball velocity wost wst Difference N= 12 Min- Max X SD Min-Max X SD z P km.h m.s * p < 0.01; 1 m.s kmh -1 wost: without a singed target ; wst: with the singed target * Table 2. The angular velocity of the upper arm segment at the beginning of the throw and at the pre-release of the ball Angular Velocity (.s -1 ) N= 12 Internal Rotation Adduction wost wst Difference X SD X SD Z p BoT PR * BoT PR Flexion BoT PR * *p < 0.01 wost: without a singed target ; wst: with the singed target; BoT: beginning of throw; PR: pre-release

4 24 Zeynep Inci Karadenizli et al.: Accuracy and Velocity of the Elite Female Turkish Handball Players Table 3. Resultant linear velocity of the elbow and shoulder joints at the beginning of the throw and at the pre-release of the ball Resultant Linear velocity (m.s -1 ) wost wst Difference X SD X SD Z P Elbow Shoulder Joint BoT PR BoT PR * p < 0.01 wost: without a singed target ; wst: with the singed target; BoT: beginning of throw; PR: pre-release Table 4. The angular velocity of the rotation of shoulder joint and pelvis at the beginning of the throw and at the pre-release of the ball Angular velocity (.s -1 ) Horizontal (xy) wost wst Difference X SD X SD Z P Shoulde Joint Pelvis BoT PR BoT PR * p < 0.01 wost: without a singed target ; wst: with the singed target; BoT: beginning of throw; PR: pre-release 4. Discussion We assessed the relationship between the throwing velocity and the accuracy of elite female handball players as the execution of the task was becoming harder due to the limited target area in the goal. We have found that the fastest accurate cross over step throw to the goal with signed target was 85 km.h -1 and without target it was 88 km.h -1. Similar to our results, the maximum ball velocity reported was 85 km.h -1 for female handball players[12]. Jensen et al. (1999) were also reported the throwing velocity as 94.08±5.1km.h -1 [20], and Gorostiaga et al. (2005)[1] as 25.3 ± 2.2 ms -1 (91.08 ± 7.92 kmh -1 ) for elite male handball players during overarm throwing with the cross over step[1]. Although these were higher than ours and the results of Jöris et al. (1985) [12], obviously gender differences were the main criteria as were reported by Freeston et al. (2007) [3]. However, we aimed to examine the effectiveness of the speed-accuracy trade-off[2,3,5,7] on the maximum accurate throws to the singed target and to understand at which point the accurate velocity is reduced to the critical level while the players were performing their maximum effort. As we expected, their mean maximal ball velocity to the goal with the singed target (65.92 ± km.h -1 ) was 6.17% slower than the goal without the target (70.25 ± km.h -1 ) (p < 0.01). This data supports our hypothesis that the accurate throwing velocity of the players to the singed target was 93.83% of their maximum. This was reported as 85% of maximum overarm throwing velocity of the experienced handball players[8] and 75% to 85% of maximum of throwing of the cricket players[3]. The maximal accurate overhead throwing velocity found in this study is higher than the reported results, however, this might be related with the sports experience of the players in this study. Although Van den Tilliar et al. (2006) emphasized the importance of velocity on accuracy without considering the training experience of the elite handball players[21], the results of the Freestone et al. (2007) highlights the importance of experience since the elite senior female players' throwing velocity (83%) was reported higher than the elite under-females (79.5%) in cricket[3]. Therefore, further studies are possibly required to determine the critical velocity that could be achieved during different throwing techniques in both gender. On the other hand, since the maximum throwing velocities belong to one of the left handed players, as Dane and Erzurumluoglu stated, this may also be related with the handedness of the athletes[22]. Thus, the effectiveness of handedness on the acquired velocity may be another feature to be worked on. It was stated that the shoulder joint has an important role during the overarm throws due to the open kinetic loop and that the velocity transferred from the shoulder segment has potential to generate the linear extension of the elbow segment[23]. Supporting this, Hong (2001) stated that the upper trunk and shoulder are the main proximal segments assisting the elbow joint to produce rapid elbow extension near the ball release[24]. The overarm throw to the goal without signed target, was higher than the goal with signed

5 International Journal of Sports Science 2014, 4(1): target and it exhibited a significant effect of the angular velocity of the shoulder internal rotation to the resultant linear acceleration of the elbow joint (p < 0.02). However, as the accuracy of the throwing action is becoming more important due to difficulty of the task (throwing to the goal with singed targets), a decrements in the angular velocity of the upper arm segments occurred. Table 2 reveals that this was 66% in flexion and 55% in internal rotation of the shoulder joint when it was compared with the maximum angular velocity of players and it was considered as their maximum exertion while throwing to the goal without a signed target (p < 0.01). This decrease might result with a slowing down of the transfer of velocity to elbow joint, which can be related with the diminished ball velocity (6.17%) (p < 0.01) during the acquired throws with the singed target. This may be related with the nonproximal-to-distal sequence for the linear velocities of shoulder, elbow and wrist of the throwing arm in handball, which is due to the fact that different conditions may occur during the game then to those involved in other throwing activities[9]. For instance, the handball players either have defenders in front of them and/or the goal keepers to beat, however, baseball pitchers, javelin throwers, even the football quarterback have actually nobody in front of them while throwing the ball or the javelin. The significant relationship with the throwing performance and the elbow extension, as well as the level of internal rotation velocity of the shoulder at ball release was reported[25]. We have found a decrease in the velocity of the players that it is one of the features of their throwing performance during the signed target as the shoulder internal rotation and flexion decreases for the sake of accuracy (p < 0.01). On the other hand, during the without signed target throw, since the task is easier than the signed target, as it is defined in Fitt's Law, pelvic rotation and forearm internal rotation velocities were higher (p < 0.05). Additionally, these differences may also be explained by the timing of the segmental velocities as the maximal linear velocity of the shoulder occurred after the maximal linear velocity of the elbow[20]. Table 4 reveals that this may explain the decrease of the resultant linear velocities of both the shoulder (37%) and the elbow (10%) joints, though they were not significant. These findings may point out the importance of elbow and forearm for the transfer of velocity from shoulder to the throwing hand and the ball. However, pelvic rotation has also a leading effect on the internal rotation (pronation) of the forearm and the hand. It was stated that the timing of the wrist, elbow and hip joints and their maximum resultant linear velocities cause the differences observed in ball velocity at the moment of pre-release[8]. In relation to this, it was reported that the maximal angular velocity of the wrist occurs earlier than the elbow extension in the throwing side[2]. This supports the idea of Hore et al. (2005) that the wrist flexion contributes only a very small amount to the total throwing velocity, but may be more crucial for throwing accuracy[25]. Unfortunately, the results of the tests have low statistical power, which may be due to the relatively small sample size that was considered as the limitation of the study. Additionally, the absence of the hand movement assessment was also a limitation of this study that can be considered as a different unique study. 5. Conclusions In conclusion, we can express that during the overarm throw with a cross over step in handball, there has been a deceleration in the shoulder joint and an acceleration in the elbow joint at pre-release of the ball. Pelvic rotation towards the throwing arm is positively effecting the shoulder internal rotation, that is thought to be responsible for the accuracy of shoulder joint and upper arm. In the light of these outcomes, we may suggest to the trainers emphasize on the elbow joint extension and internal rotation. Also the shoulder joint internal rotation as well as the pelvic rotations of the handball players may improve their performance in the training programs. ACKNOWLEDGEMENTS This study was supported by Marmara University Scientific Researches Committee (Project number SAG-D ). The authors would like to thank to the National Female Handball Team for their contribution to this study. 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