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Fine body movements and the cardiac cycle in archery 总被引：3，自引：1，他引：2
This study examined the relationships between postural sway, aiming time, the cardiac cycle time and the placement of the first finger movement within the electrocardiac cycle, with the quality of the arrow shot. A small group of elite male and female archers who shot either the recurve or the compound bow, freestyle or bare bow was used in this study. A total of 240 arrows were shot, classified as being of good, average or bad quality and analysed in detail. The analyses were undertaken over two occasions up to 100 days apart. The area of postural sway, as measured by the movement of the centre of pressure coordinates, varied significantly (P less than 0.05-0.001) both within and between trials for all archers and for all quality of arrows shot. There was a tendency for the area of postural sway to increase as the quality of the arrow shot decreased. This increase in postural sway exceeded, for arrows of bad quality, that exhibited as normal postural sway when standing relaxed and addressing the target with the hands at the side. Aiming time was variable within the quality of arrow shot, although it was consistent for each archer. In some cases the aiming time increased as the quality of the arrow decreased, whereas in the case of bare bow archery the aiming time tended to decrease as the quality of the arrow deteriorated. The cardiac cycle time increased significantly (P less than 0.05-0.01) as the archers approached the loose of the good quality arrows but there was no significant increase in cardiac cycle time when arrows of average or bad quality were shot. The most consistent parameter related to the quality of the shot was the placement of the first finger movement within the ST phase or the mid-cycle phase of the electrocardiogram for arrows of good quality (P less than 0.0001). 相似文献
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A predominant archery coaching tenet holds that the most effective means of releasing the bow string is by relaxation of the finger flexor muscles without activation of finger extensors. To evaluate the validity of this view, EMG patterns of the flexor digitorum superficialis and extensor digitorum muscles of the draw arm were examined using surface EMG electrodes in 15 highly skilled archers as each performed six shots. Each archer displayed consistent EMG patterns from shot-to-shot and two distinct flexor-extensor patterns were exhibited by the sample. The first, characterized by eight of the archers, supported the relaxation principle. For these archers, both flexor and extensor digitorum activity decreased markedly immediately prior to or at arrow release. The second pattern, characteristic of the remaining seven archers, contradicted the coaching tenet. While the flexor digitorum pattern was essentially the same as that described for the first pattern, the extensor digitorum displayed a marked increase in activity just prior to release, indicating that string release was facilitated by an active extension of the fingers. It was concluded that highly skilled archers do not predominantly reflect a release consistent with the coaching canon and that factors other than the string release mechanism discriminate the performances of skilled archers. 相似文献
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The ability to recognize patterns of play is fundamental to performance in team sports. While typically assumed to be domain-specific, pattern recognition skills may transfer from one sport to another if similarities exist in the perceptual features and their relations and/or the strategies used to encode and retrieve relevant information. A transfer paradigm was employed to compare skilled and less skilled soccer, field hockey and volleyball players' pattern recognition skills. Participants viewed structured and unstructured action sequences from each sport, half of which were randomly represented with clips not previously seen. The task was to identify previously viewed action sequences quickly and accurately. Transfer of pattern recognition skill was dependent on the participant's skill, sport practised, nature of the task and degree of structure. The skilled soccer and hockey players were quicker than the skilled volleyball players at recognizing structured soccer and hockey action sequences. Performance differences were not observed on the structured volleyball trials between the skilled soccer, field hockey and volleyball players. The skilled field hockey and soccer players were able to transfer perceptual information or strategies between their respective sports. The less skilled participants' results were less clear. Implications for domain-specific expertise, transfer and diversity across domains are discussed. 相似文献
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The ability to recognize patterns of play is fundamental to performance in team sports. While typically assumed to be domain-specific, pattern recognition skills may transfer from one sport to another if similarities exist in the perceptual features and their relations and/or the strategies used to encode and retrieve relevant information. A transfer paradigm was employed to compare skilled and less skilled soccer, field hockey and volleyball players' pattern recognition skills. Participants viewed structured and unstructured action sequences from each sport, half of which were randomly represented with clips not previously seen. The task was to identify previously viewed action sequences quickly and accurately. Transfer of pattern recognition skill was dependent on the participant's skill, sport practised, nature of the task and degree of structure. The skilled soccer and hockey players were quicker than the skilled volleyball players at recognizing structured soccer and hockey action sequences. Performance differences were not observed on the structured volleyball trials between the skilled soccer, field hockey and volleyball players. The skilled field hockey and soccer players were able to transfer perceptual information or strategies between their respective sports. The less skilled participants' results were less clear. Implications for domain-specific expertise, transfer and diversity across domains are discussed. 相似文献
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Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age?=?24.7?±?7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers. 相似文献
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Effect of graded competition on student opportunities for participation and success rates during a season of Sport Education 总被引：1，自引：0，他引：1
Peter A. Hastie Jeffrey K. Ward Sheri J. Brock 《Physical Education & Sport Pedagogy》2017,22(3):316-327
Background: A guiding principle of Sport Education is that all students get equal opportunity to play, which is expedited through the use of small-sided contests. One element included within the philosophy of Sport Education is that of ‘graded competition.’ In graded competition, leagues are arranged that match students of similar skill level against one another, and in some cases, even the game forms are different across the competition levels. To date, there are no studies that have examined the utility of graded competition as promoting either student engagement or learning. Purpose: The purpose of this study was to test the hypothesis that using graded competition would increase opportunities for game involvement and success rates of both higher and lower skill level students. Participants and setting: The participants in this study were 106 fourth-grade students (51 boys and 55 girls, aged 10–11) from two physical education classes within an elementary school in the southeastern United States. The content was an 18-lesson season of mini-handball taught following the principles of Sport Education. While the overall season format for both classes was the same, the composition of teams varied between the two. In the first class, all teams were heterogeneous with a mix of higher and lower skilled players. These students were able to divide into their sub-teams in any combination they wished. In the second class, two homogeneous leagues were formed; one consisting of teams with all higher skilled students and the other with teams of all lower skilled students. There was no inter-league play. Rather, there were two parallel competitions and two championships. Methods: Digital video records were made of 76 games played during the seasons. Each time a player (a) made contact with the ball (a pass, catch, or interception), (b) was the target of a pass but did not receive it (overthrow or interception), or (c) was involved with a shot on goal (as shooter or goalkeeper), that activity was recorded. A 2 (skill: high/low)?×?2 (sex)?×?3 (grouping: all low/all high/mixed) full factorial mixed analysis of variance was conducted on the following dependent variables: (a) percent success, (b) ball engagement rate, and (c) efficiency, with the game being the unit of analysis. Findings: The key finding from this study was that in terms of success rates, engagement rates and playing efficiency, lower skilled students seemed to be at a disadvantage when they participated alongside higher skilled classmates. While less severe, there were also decrements in higher skilled student success rates and efficiency in these mixed-skill conditions. By consequence, while higher skilled boys could thrive in either homogenous or mixed level competitions, many girls and all students with lower skill levels benefitted from playing against students of similar skill levels. Conclusions: The grouping of students in terms of skill level has implications for their in-game behaviors, for the extent to which they can develop improved game performance, and potentially for their motivation to persist during play. 相似文献
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《European Journal of Sport Science》2013,13(4):213-222
Abstract At the end of the aiming phase, an archer pulls the arrow back a little bit before he releases the shot. This pulling back of the arrow is called the “final pull”. Simultaneous with the final pull, the archer has to hold the bow calm. The aim of this paper was to examine the motion of the bow and the final pull in highly skilled archers. From a technological point of view, we wished to develop a system to measure the draw-length in the final pull that could be used during archers’ normal training. Seven archers (two males, five females), all of whom were participants at the Junior World Championships and German National Championships, performed 66 shots indoors at a target 30 m away. Each archer shot the same bow as used in competition. On-target trajectories of the aim point movement were measured. Also, the alterations of the draw-length in the final pull were determined. The results suggest that irregularities in the final pull have a negative influence on archers’ scores. Intra-individually, a smaller range of motion of the bow in the last second before the shot appears to have a positive influence on archers’ scores. 相似文献
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This study reinvestigated and extended the findings of Landers and Landers (1973), which examined the influence of skilled and unskilled teacher and peer models on motor performance. Sixth grade females (N = 100) were randomly assigned to groups in a 2 x 2 (Model Type x Model Skill) factorial design or to a no-model group. In the treatment groups, subjects observed one of four unfamiliar models--(a) a skilled teacher, (b) an unskilled teacher, (c) a skilled peer, or (d) an unskilled peer--perform on the Bachman ladder task. Subjects performed 30 trials of the task and also completed self-efficacy questionnaires on three occasions. Results showed that subjects who watched a skilled model performed better than subjects who watched an unskilled model. Unlike the Landers and Landers study, no model type by model skill interaction was found. In addition, the skilled model group reported higher efficacy beliefs than the control group after performing and were more efficacious than the unskilled model subjects both after watching the model and after performing. These results suggest when students view unfamiliar models, the skill rather than the status of the model may be more salient. 相似文献
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Abstract This study reinvestigated and extended the findings of Landers and Landers (1973), which examined the influence of skilled and unskilled teacher and peer models on motor performance. Sixth grade females (N = 100) were randomly assigned to groups in a 2 × 2 (Model Type × Model Skill) factorial design or to a no-model group. In the treatment groups, subjects observed one of four unfamiliar models—(a) a skilled teacher, (b) an unskilled teacher, (c) a skilled peer, or (d) an unskilled peer—perform on the Bachman ladder task. Subjects performed 30 trials of the task and also completed self-efficacy questionnaires on three occasions. Results showed that subjects who watched a skilled model performed better than subjects who watched an unskilled model. Unlike the Landers and Landers study, no model type by model skill interaction was found. In addition, the skilled model group reported higher efficacy beliefs than the control group after performing and were more efficacious than the unskilled model subjects both after watching the model and after performing. These results suggest when students view unfamiliar models, the skill rather than the status of the model may be more salient. 相似文献
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目的：对不同注意力焦点下射箭运动员执行技术动作时的姿态控制特征进行研究。方法：基于传统线性测量及非线性动力学两个视角对运动员执行技术动作时的运动学与动力学数据进行分析。结果：（1）外部注意力焦点减少了运动员右脚左右及前后方向上的压力中心（COP）最大位移以及双脚的COP包络面积 ;（2）外部注意力焦点增加了运动员双腿踝关节、左腿膝关节累计运动幅度,以及双腿前后方向、左腿左右方向上的COP样本熵 ;（3）注意力焦点与运动技术水平在左右方向的COP最大位移指标上存在交互作用 ;（4）不同技术水平运动员的姿态控制能力差距明显。结论：（1）外部注意力焦点通过增强下肢关节协调来增强对干扰的应对能力从而改善姿态控制 ;（2）外部注意力焦点的促进作用随着技术水平的提升逐渐下降 ;（3）运动技术水平越高,姿态控制能力越强 相似文献
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Oliver R. Runswick André Roca A. Mark Williams Allistair P. McRobert Jamie S. North 《Journal of sports sciences》2019,37(5):537-543
Skilled anticipation is underpinned by the use of kinematic and contextual information. However, few researchers have examined what happens when contextual information suggests an outcome that is different from the event that follows. We aimed to bridge this gap by manipulating the relationship between contextual information and final ball location in a cricket-batting task. We predicted that when contextual information is congruent with the eventual outcome then anticipation would be facilitated. In contrast, when contextual information is incongruent, this would lead to a confirmation bias on kinematic information and result in decreased anticipation accuracy. We expected this effect to be larger in skilled performers who are more able to utilise context. Skilled and less-skilled cricket batters anticipated deliveries presented using a temporally occluded video-based task. We created conditions whereby contextual information and event outcome were either congruent or incongruent. There was a significant skill by condition interaction (p < 0.05). The skilled group anticipated significantly more accurately than the less-skilled group on the congruent trials. Both groups anticipated less accurately on incongruent trials, with the skilled participants being more negatively affected. Skilled performers prioritise contextual information and confirmation bias affects the use of kinematic information available later in the action. 相似文献
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Oar force and oar angle data resulting from a 6‐min maximal rowing ergometer test undertaken by novice (n = 9), good (n ‐ 23) and national (n = 9) level male rowers, were used to identify biomechanical performance variables which accurately discriminated between rowers of differing ability levels. The variables included two work capacity measures, mean propulsive power output per kilogram of body mass (W kg‐1) and propulsive work consistency (%), and two skill variables, stroke‐to‐stroke consistency (%) and stroke smoothness (%). Discriminant function analysis indicated the presence of two functions, both of which clearly indicated the importance of mean propulsive power output per kilogram of body mass as a discriminating variable. Function 2 gave greater weight to stroke‐to‐stroke consistency and stroke smoothness than function 1; however, function 1 was the most powerful discriminator. Classification procedures were used to predict the ability level to which a rower most likely belonged and involved defining the ‘distance’ between each rower and each ability level centroid, with the rower being classified into the ‘nearest’ ability level. These procedures indicated that 100% of the elite, 73.9% of the good, 88.9% of the novice and 82.9% of all rowers were correctly classified into their respective skill levels. Stepwise discriminant analysis included the variables in the following order: mean propulsive power output per kilogram of body mass, stroke‐to‐stroke consistency, stroke smoothness and propulsive work consistency (P < 0.001). The results of this study indicate that biomechanical performance variables related to rowing capacity and skill may be identified and used to discriminate accurately between rowers of differing skill levels, and that, of these variables, propulsive work consistency is the least effective discriminator. 相似文献
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In this study, we examined the influence of internal and external attention instructions on the performance of a pitch shot by golfers who were either highly skilled (mean handicap = 4) or low skilled (mean handicap = 26). Ten golfers in each skill group used a 9-iron to pitch a ball as close as possible to an orange pylon, which was located at distances of 10, 15, 20 or 25 m from the golfer. Focus of attention was manipulated within participants (counterbalanced across golfers). Under internal focus of attention instructions, the participants were told to concentrate on the form of the golf swing and to adjust the force of their swing depending on the distance of the shot. For the external focus of attention conditions, the participants were told to concentrate on hitting the ball as close to the target pylon as possible. The most intriguing finding was an interaction of skill with focus of attention instructions for variability in performance. Similar to the findings of Wulf and colleagues, the highly skilled golfers performed better with external attention instructions than with internal focus instructions. In contrast, the low-skill golfers performed better with the internal than with the external focus of attention instructions. These findings are discussed relative to theoretical issues in motor learning and practical issues for golf instruction. 相似文献
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The study investigated the coordination and variability of posture and pistol motion for skilled pistol shooters and novices in a pistol-aiming task. The participants stood on a force platform and held a pistol with the preferred arm to aim for accuracy to a target on 30 s trials. The results revealed that the amount of the centre of pressure (COP) and pistol motion was lower for the expert than novice group. The time–varying structure of COP as indexed by multiscale entropy (MSE) and detrended fluctuation analysis (DFA) was also lower for the expert than the novice group. The relative phase between the COP in the anterior–posterior (AP) and pistol in the AP and between the COP in the medial–lateral (ML) and pistol in AP was close to inphase for the both groups. However, for the novice group the coordination patterns of posture and pistol motion were more variable with the pistol motion leading the posture motion while it was lagging in the skilled group. The findings show different qualitative and quantitative dynamics in pistol-aiming as a function of skill level with postural control foundational to supporting the reduced dispersion and complexity of the skilled arm-pistol motion. 相似文献
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Biomechanical understanding of the knee joint during a golf swing is essential to improve performance and prevent injury. In this study, we quantified the flexion/extension angle and moment as the primary knee movement, and evaluated quasi-stiffness represented by moment–angle coupling in the knee joint. Eighteen skilled and 23 unskilled golfers participated in this study. Six infrared cameras and two force platforms were used to record a swing motion. The anatomical angle and moment were calculated from kinematic and kinetic models, and quasi-stiffness of the knee joint was determined as an instantaneous slope of moment–angle curves. The lead knee of the skilled group had decreased resistance duration compared with the unskilled group (P < 0.05), and the resistance duration of the lead knee was lower than that of the trail knee in the skilled group (P < 0.01). The lead knee of the skilled golfers had greater flexible excursion duration than the trail knee of the skilled golfers, and of both the lead and trail knees of the unskilled golfers. These results provide critical information for preventing knee injuries during a golf swing and developing rehabilitation strategies following surgery. 相似文献
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The trajectory of the clubhead close to ball impact during the golf swing has previously been shown to be planar. However, the relationship between the plane orientation and the orientation characteristics of the clubhead at ball impact has yet to be defined. Fifty-two male golfers (27 high skilled, 25 intermediate skilled) hit 40 drives each in an indoor biomechanics laboratory. This study successfully fitted the trajectory of the clubhead near impact to an ellipse for each swing for players of different skill levels to help better explain this relationship. Additionally, the eccentricities of the ellipses were investigated for links to skill level. The trajectory of the clubhead was found to fit to an ellipse with RMSE of 1.2 mm. The eccentricity of the ellipse was found to be greater in the high-skilled golfers. The club path and angle of attack generated from the ellipse fitted clubhead trajectory were found to have a normalised bias-corrected RMSE of 2% and 3%, respectively. A set of “rule of thumb” values for the relationship between the club path, angle of attack and delivery plane angle was generated for use by coaches. 相似文献
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The effectiveness of pre-performance routines on skilled performance in a self-paced skill has yet to be verified. In this study, we examine the importance of temporal and behavioural consistency in these routines. The duration and specific pattern of behaviours exhibited before each free throw (n = 284) were observed during 14 National Basketball Association play-off games. An intra-individual standardized score was calculated for each shot's duration. Each player's dominant behavioural routine was identified and each shot was classified as "sequence followed" or "sequence not followed". No difference was observed in the success rates of shots associated with brief, long, and regular duration routines (P > 0.05). However, players were more successful when they followed their dominant behavioural sequence (83.77% success) than when they deviated from their specific behavioural pattern (71.43% success) (P < 0.05). The findings are interpreted in light of relevant theory and implications for practice are discussed. 相似文献