Biomechanics and Medicine in Swimming XI

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correctly executed, in order for the whole to be effective. It is possible that inefficient swimming technique has a negative effect on shooting accuracy. Effective swimming technique is one of the main factors that determines swimming performance in a given distance. One other main factor is the fitness level. In the present study, the participants of higher swimming performance had greater shooting accuracy than participants with lower swimming performance. According to our results, it was revealed that fitness level is a significant predictor of accuracy either in shooting in a static position or after previous swimming. However, Δ values in accuracy between shot in a static position and after previous swimming were not different in relation to fitness level. Significantly high correlation was observed in swimming performance and training age. Moreover, training age and swimming performance were significantly correlated with shooting accuracy either in a static position or after previous swimming. It seems that yearly training improves shooting accuracy. The swimming performance, also, which can be considered not only as a fitness level index but as an index of adequate swimming technique, strongly affects shooting accuracy. According to our findings, our hypothesis that shots in a static position would be more accurate than after previous swimming and that waterpolo players of greater training age and those with better swimming performance would be more accurate compared with inexperienced water-polo players, of lower fitness level, was verified. conclusIon The present study is the first to investigate shooting accuracy in a static position and after previous swimming of water-polo players differing in training age and swimming performance. These results suggest that shots in a static position are more accurate than shots after previous swimming. Additionally, shooting accuracy is highly dependent on training age. The inexperienced water-polo players were less accurate than players of greater training age. According to our results, it seems that shooting accuracy is highly dependent on swimming performance. The water-polo players of lower swimming performance had a significantly lower percentage of accurate shots than players of greater swimming performance.There is no difference in accuracy between shot in a static position and after previous swimming as Δ values, in relation to training age or swimming performance. Previous swimming has a negative effect on shooting accuracy, regardless of the training age. The data of this study should be applied to athletes of similar level and could provide water polo coaches with guidelines for training. reFerences Bloomfield, J., Blanksby B.A. & Ackland T. (1990). The influence of strength training on overhead throwing velocity of elite water polo players. Aus J Sci Med Sport. 22, 63-67. Erquli, F. & Supej, M. (2009). Impact of fatigue on the position of the release arm and shoulder girdle over a longer shooting distance for an elite basketball player. J. Strength Cond Res. 23(3), 1029-1036. Feltner, M.E. & Nelson, S.T. (1996). Three-dimensional kinematics of the throwing arm during the penalty throw in water polo. J Applied Biomech. 12, 359-382. Triplett, T., Fleck, S.J., & Smith, S.L. (1991). Isokinetic torque and throwing velocity in water polo. Med Sci Sports Exer. 23, 11-14. Royal, K.A., Farrow, D., Mujica, I., Halson, S.L., Pyne, D. & Abernethy, B. (2006). The effects of fatigue on decision making and shooting skill performance in water polo players. J. Sport Sci. 24(8), 807-815. chaPter4.trainingandPerformance The Effect of Cognition-Based Technique Training on Stroke Length in Age-Group Swimmers schmidt, A.c. 1 , ungerechts, B.e. 2 , Buss, W. 1 & schack, t. 2 1University of Göttingen, Department of Society and Training, Germany 2University of Bielefeld, Department of Neurocognition and Action – Biomechanics, Germany This study deals with a specific and innovative aspect of long-term performance-planning in swimming: cognition-based technique training. Based on the studies of Thomas Schack on the cognitive architecture of movements, the cognition-based technique training method was developed and proved the first time in swimming. The study applies the program ‚Split’, which has already been successfully used in other sports. Split uses distance scaling between the elements of a system of concepts to measure conceptual structures. To evaluate the potential introduction of cognition-based technique training in long-term performanceplanning of swimmers, biomechanical criteria were used. Key words: age-group swimmers, crawl, representational structure, stroke distance, stroke rate IntroductIon Highly skilled swimmers aspire to cover as much distance per stroke as possible. According to Reischle (1988) and Arellano et al. (1991) an improved swimming technique results in a longer stroke length. Therefore it is likely that the athlete swims the same race-distance with fewer strokes and probably in less time. In the case of less time and increased stroke length, the so-called stroke-index (speed squared and multiplied by stroke length) will also be increased. Knowing this, it is obviously important to increase the stroke length of any swimmer. To gain more effective underwater-movement, the swimmer could increase his power (without technical training this might be limited soon) and / or try to optimize his motion sequence in relationship to the water. In contrast to most other sporting activities, swimmers do not have a fixed base to push off. Swimmers, instead, produce propulsion due to interaction of body and water-mass. Therefore it is very important to educate swimmers at the beginning of long term performance planning on how to work with water properly while executing regular strokes. To reach this, emphasis should be placed on how stroking is mentally represented by swimmers, even age-group swimmers. Advanced age-group swimmers, in order to improve the efficacy of their stroking actions, have to control the stroke-technique mentally as a prerequisite to optimize details of motion sequences. In this context a cognitive intervention can be used which is based on the Structural Dimension Analysis of Motor Memory (SDA-M) according to SCHACK (2003). UNGERECHTS/SCHACK (2006) did a first study of the representation of butterfly-swimmers using SDA-M and described the method. SDA-M is used to describe mental representation structures and it enables statements about the cognitive architecture of complex movements in the long-term memory. This means, interpreting the results, one can understand how the swimmer is thinking about his movements, which parts (nodes) he connects closely and where there are large distances or connections, which – biomechanically – are not reasonable. So the major cause of problems of (stroking) actions can be localized in a way which fits with the demand of effective communication between coach and athlete. The purpose of this paper is to examine the effect of cognition-based technique training on the stroking ability of age-group swimmers. 283
BiomechanicsandmedicineinswimmingXi Method The empirical study was carried out on three test days. A test group and a control group with 23 and 24 age-group swimmers, respectively, were involved in the study. Between the first and second test day the test group performed specific workouts for six weeks. On the test days the program ‘Split’ (SCHACK et al., 2000) was used to evaluate the representational structure and the swimmers also performed a swimming test of 2 x 25 meters crawl stroke at full speed. The control group only performed the swimming test. To evaluate the long-term educational effects of the cognition-based training, the swimmers of both groups trained for another 12 weeks. The study was concluded by a final swimming test for both groups and the test group also used ‘Split’ again. During the sprints on the test days a) the time over a 10m distance – from 10 to 20 m – and b) the stroke rate were measured and finally the stroke length and the stroke index were calculated (the data of the two trials were averaged). “Split” was used to sort out “basic action concepts”, called nodes, representing arm/hand actions during crawl stroke. The nodes were established by the coach in close relation to how he/ she normally describes stroking, however in a more structured manner. After sorting out all nodes according to the criteria, if they belong to the anchor node or not, as result one gets an impression of the mental representation, which the swimmer has of its motion sequence (in this example of the crawl arm stroke). By means of this computer programme, the so-called split technique is used in order to achieve the data of proximity. “The SDA-M consists of four steps: First, a special split procedure involving a multiple sorting task delivers a distance scaling between the BACs of a suitably predetermined set. Second, a hierarchical cluster analysis is used to transform the set of BACs into a hierarchical structure. Third, a factor analysis reveals the dimensions in this structured set of BACs, and fourth, the cluster solutions are tested for non-variance within- and between-groups (for psychometric details, see Schack, 2001, 2002” (BLÄSING et al. 2009). The mental representation is described by a so-called dendrogram and clusters (groups of individual nodes). Analyzing the dendrograms and the clusters special training-programs were created (theoretical and practical), which were performed during the six week training period. The individual stroking instructions were inferred from the results of the SDA-M tests. The communication between coach and athlete was based on defined notes. During the workouts established drills were used in another context, dealing with one or more BAC and their connection to each other. First the coach explained to the athlete (a) the results of split and in most of the cases (b) again all the nodes and their impact in the stroking action, especially the ‘problem-nodes’ of the athlete. This was the basis of the workouts covering each node with drills and then later on groups of nodes and especially the ‘problem’ nodes. So in each workout (after one or more drills) by using the nodes, the connection of one node to the neighbor-nodes or a group of nodes to each other was discussed. During stroking the swimmer had to concentrate on what he was doing and on his feelings (e.g. stroking, propulsion) telling this later to his coach. As an example, the BACs of one of the training groups are shown here: Fingers enter water (1), Shrugging shoulders (2), Rolling to side of action (3), Downwards (4), Pronation (5), Elbow extension (6), Rolling back (7), Slicing hand (8), Breathing (9), Hand forward (10). results The following figures show the representational structure of one swimmer at test 1, 2 and 3. 284 Fig. 2 Dendrogram of one swimmer (test 1) without any cluster and without a real regularity of the nodes. The distances between the nodes are quite large, therefore do not cluster. Fig. 3 Dendrogram of the same swimmer after the six week training period (test 2) with three clusters (all nodes are integrated in clusters and are in biomechanical regularity) Fig. 4 Dendrogram of the same swimmer after 18 weeks (six weeks specific training and 12 weeks ‘normal’ training (data 3). The dendrogram shows four clusters, regularity of nodes, but also partly increased distances between nodes. At test 1 the structure is not really sorted, the distances between the BACs are quite large (it does not have any clusters). After the training period
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Pahlen Norge AS Pahlen Norge AS Cha
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