Postural tremor and control of the upper limb in air pistol shooters

Abstract

A postural tremor appears whenever someone attempts to maintain a steady position against gravity. We examined the postural tremor that occurred while air pistol shooters were taking aim so as to compare the coordinative control of the shooters and to identify the features critical to successful shooting. Ten elite and ten pre-elite athletes participated in pistol shooting at 10 m, and the postural tremors in the pistol and upper limb were recorded with lightweight accelerometers. Exploratory analysis showed that the elite shooters had smaller tremor amplitudes than the pre-elite shooters in the pistol and distal arm segments. Compared with the pre-elite shooters, the elite shooters had a smaller tremor amplitude in the lateral direction relative to that in the vertical direction, together with weaker tremor coupling in the lateral direction and stronger vertical coupling of the pistol–hand complex. The resulting shot performance was inversely related to the amplitude of the tremor and to the 8–12 Hz spectral peak of the lateral tremor in the pistol–hand complex. We conclude that the postural tremors of air pistol shooters are associated with the skill of the shooters, and that the elite shooters could optimize the control of the pistol–hand complex, which strongly determined success in shooting.     

Jump higher,run faster: effects of diversified sport participation on talent identification and selection in youth basketball

ABSTRACT

The aims of this study were to examine the medium-term effects of previous experiences during early stages of sport development on physical capacities of under-13 (U-13) talented basketball players and, to identify variables that discriminated under-14 (U-14) national team training camp selection. Anthropometrical and physical measurements were collected during a basketball training camp. Previous sport experiences (6–10 years), maturity offset, power outputs for jumping and sprinting were determined. A cluster analysis was used to allocate the subjects according to their different levels of sport experiences (more specialized vs. less specialized) to allow creating a dummy variable for the subsequent analysis of the physical variables. A stepwise discriminant analysis was computed to identify the construct that best classifies selected and non-selected players for U-14 national team training camp. The less specialized group outscored more specialized in all physical parameters, irrespectively of gender. The Abalakov Jump Peak Power and Predicted Adult Height (PAH) could successfully discriminate selected from non-selected players for U-14 national team training camp in boys and PAHin girls. The diversified and non-specific sport stimulus during early ages seem to be determinant to the acquisition and development of fundamental movement skills of talented basketball players.     

Three-dimensional analysis of blade contact in an ice hockey slap shot,in relation to player skill

The purpose of this study was to examine the three-dimensional movement profile of the blade during a stationary slap shot, as a function of player skill level. A total of 15 subjects participated; eight were classified as elite and the remaining seven were recreational. Performances were evaluated by simultaneously recording the movements of the stick’s lower shaft and blade with high-speed video (1000 Hz), the time of stick-ground contact with two uniaxial forceplates and time of blade-puck contact with a uniaxial accelerometer mounted within the puck. Data were analysed with a two-way MANOVA for several dependent variables including linear kinematics, temporal phase data and global angles. The results indicated that skill level affected blade kinematics, with elite shooters tending to alter timing parameters (i.e. phase length), magnitude of linear variables (i.e. displacement, etc.) and the overall blade orientation to achieve a higher velocity slap shot. These analyses identified a unique ‘rocker’ phase within the execution of the slap shot in both groups.     

从第15届世锦赛看中国女篮与世界强队的差距

通过对第15届女篮世锦赛中国女篮全部七场比赛技术统计的分析,从投篮命中率、得分能力、篮板球能力、助攻、失误、抢断、盖帽等技术与世界强队进行对比研究,分析中国女篮与世界强队的差距。     

Postural tremor and control of the upper limb in air pistol shooters

A postural tremor appears whenever someone attempts to maintain a steady position against gravity. We examined the postural tremor that occurred while air pistol shooters were taking aim so as to compare the coordinative control of the shooters and to identify the features critical to successful shooting. Ten elite and ten pre-elite athletes participated in pistol shooting at 10 m, and the postural tremors in the pistol and upper limb were recorded with lightweight accelerometers. Exploratory analysis showed that the elite shooters had smaller tremor amplitudes than the pre-elite shooters in the pistol and distal arm segments. Compared with the pre-elite shooters, the elite shooters had a smaller tremor amplitude in the lateral direction relative to that in the vertical direction, together with weaker tremor coupling in the lateral direction and stronger vertical coupling of the pistol-hand complex. The resulting shot performance was inversely related to the amplitude of the tremor and to the 8-12 Hz spectral peak of the lateral tremor in the pistol-hand complex. We conclude that the postural tremors of air pistol shooters are associated with the skill of the shooters, and that the elite shooters could optimize the control of the pistol-hand complex, which strongly determined success in shooting.     

Managing pressure: patterns of appraisals and coping strategies of non-elite and elite athletes during competition

Abstract

The purpose of this study was to compare moment-to-moment appraisals and coping strategies of 4 non-elite and 2 elite male trap shooters during competitions and in particular during periods of competition perceived as critical to performance. Appraisals and coping patterns of trap shooters were captured via verbal reports of thinking provided between sets of shots during major competitions. Verbal reports were coded according to an appraisal and coping typology. Coded data as well as shooting performance data were subjected to a sequential analysis of probabilities of pairs of events. Fewer reports of negative appraisals (NEGAs) and more frequent reports of problem-focused coping (PFC) were observed among both elite athletes compared to non-elite athletes. After making a NEGA, non-elite shooters often progressed to the next target without attempting to cope, whereas elite shooters used both PFC and emotion-focused coping (EFC) before proceeding to the next target. After missing a target, the non-elite athletes used more EFC than expected. These results indicate that elite athletes are more likely to cope with NEGAs than non-elite athletes using a wider variety of coping strategies. Athletes might benefit from increased awareness of the potentially detrimental impact of NEGAs on performance and by integrating coping strategies within preparatory routines.     

第14届世界女子篮球锦标赛中、外女子篮球队后卫运动员技术统计数据比较研究

采用技术统计、数据分析和归纳整理等方法 ,对我国女子篮球队后卫与第 14届世界女子篮球锦标赛前 4名队后卫运动员的各项技术指标进行对比分析 ,认为中国女子篮球队后卫运动员得分能力不强导致进攻能力下降 ,防守的灵活性和有效性不够。应加快优秀后卫运动员的培养 ,相应地提高后卫运动员的攻击意识和攻击能力 ;加强后卫运动员与前锋、中锋运动员之间的配合 ,提高防守技战术变化的协同性     

Prevalence of disordered eating in elite female athletes in team sports in Greece

ABSTRACT

The purpose of the study was to assess (a) the prevalence of disordered eating (DE) in elite female team sports players compared to non-athletes and (b) to compare DE prevalence in elite female players in basketball, volleyball and water polo. One hundred and seventy-five females were recruited (age 23.10?±?5.4, BMI 21.85?±?2.3?kg/m²), 53 were elite basketball players, 42 were elite volleyball players, 34 were elite water polo players and 46 were non-athletes. Participants completed the Eating Disorders Questionnaire (EDE-Q) and a physical activity questionnaire. The EDE-Q incorporates 36 statements which relate to the occurrence and frequency of key behaviours of eating disorders, under the following four subscales: Restraint, eating concern, shape concern and weight concern and a global score of disordered eating. No differences were found in the EDE-Q subscale score and global score between athletes and non-athletes. Only 6.2% of the total number of participants exhibited DE using the global score >2.3. Water polo players had significantly higher scores in the ‘eating concern’ subscale and in the frequency of key behavioural features of DE such as binge eating episodes and objective and subjective bulimic episodes, compared to volleyball and basketball players. In conclusion, team sport elite female players do not exhibit greater prevalence of DE compared to non-athletes. Water polo, a sport that emphasises leanness and control of body weight for international distinctions, is associated with a higher tendency to exhibit DE, when compared to other team sports.     

Metabolic optimisation of the basketball free throw

The free throw (FT) is a fundamental basketball skill used frequently during a match. Most of actual play occurs at about 85% of maximum heart rate (HR). Metabolic intensity, through fatigue, may influence a technically skilled move as the FT is. Twenty-eight under 17 basketball players were studied while shooting FTs on a regular indoor basketball court. We investigated FT accuracy in young male basketball players shooting at three different HRs: at rest, at 50% and at 80% of maximum experimentally obtained HR value. We found no significant FT percentage difference between rest and 50% of the maximum HR (FT percentage about 80%; P > 0.05). Differently, at 80% of the maximum HR the FT percentage decreased significantly by more than 20% (P < 0.001) down to about 60%. No preliminary warm-up is needed before entering game for the FT accuracy. Furthermore, we speculate that time-consuming, cooling-off routines usually performed by shooters before each FT may be functional to improve its accuracy.     

第29届奥运会中国男篮攻防能力的研究

采用文献资料、录像观察、数理统计等方法,对第29届奥运会中国男篮攻防能力进行分析,研究结果表明：第29届奥运会中国男篮攻防能力与对手和世界强队存在着多方位的差距,其中在进攻上与对手的差距主要表现在：2分投篮能力和助攻能力明显弱于对手和强队,具有显著性差异。在防守能力上与对手的差距主要表现在：抢断能力明显弱于对手,具有显著性差异。建议中国男篮应着重提高进攻配合的默契性、传接球的技巧性和突破分球的能力,增强适应凶狠防守的能力、投篮时的抗干扰能力和防守的攻击性。     

不同水平的气手枪运动员击发前动作稳定性的分析

气手枪项目是手枪项目中设计精确度要求最高的项目,对技术动作的稳定性、一致性及稳、瞄、扣的协调配合等要求比较高,使用激光瞄准测试仪,对我国优秀运动员及上海队一、二线运动员进行技术动作的稳定性的测试与分析,发现优秀运动员在进入瞄区后的稳定性方面显著高于一般运动员,具体体现在枪支稳定早、稳定时间长,并且在稳定期里枪支的晃动小.     

Caffeine and performance in clay target shooting

Abstract

Controversy surrounds the influence that caffeine has on accuracy and cognitive performance in precision activities such as shooting and archery. The aim of this study was to assess the effects of two doses of caffeine on shooting performance, reaction time, and target tracking times in the sport of clay target shooting. A randomized, double-blind, placebo-controlled design was undertaken by seven elite male shooters from the double-trap discipline. Three intervention trials (2 mg caffeine · kg^?1 body mass (BM); 4 mg caffeine · kg^?1 BM; placebo) were undertaken, in which shooters completed four rounds per trial of 50 targets per round. Performance accuracy (score) and digital video footage (for determination of reaction time and target tracking times) were gathered during competition. Data were analysed using repeated-measures analysis of variance. No differences in shooting accuracy, reaction time or target tracking times among the three intervention trials or across the four rounds within each intervention were observed (P > 0.05). The results indicate that ingestion of ≤4 mg caffeine · kg^?1 BM does not provide performance benefits to elite performers of clay target shooting in the double-trap discipline.     

Late information pick-up is preferred in basketball jump shooting

Abstract

In this study we examined the timing of optical information pick-up in basketball jump shooting using an intermittent viewing technique. We expected shooters to prefer to look at the basket as late as possible under the shooting style used. Seven experts with a high shooting style and five experts with a low shooting style took 50 jump shots while wearing liquid-crystal glasses that opened and closed at pre-set intervals. In principle, under this constraint, the participants could control when they saw the basket by actively modulating the timing of their movements. Analyses of the phasing of the movements relative to the events defined on the glasses revealed that low-style shooters preferred to see the basket just before the ball passed their line of sight, whereas high-style shooters tended to view the basket from underneath the ball after it passed their line of sight. Thus, most shooters preferred to pick up optical information as late as possible given the adopted shooting style. We conclude that, in dynamic far aiming tasks such as basketball jump shooting, late pick-up of optical information is critical for the successful guidance of movements.     

Physical demands of elite basketball during an official U18 international tournament

ABSTRACT

The aims of this study were (a) to compare players’ physical demands between different playing positions in elite U18 basketball games and (b) to identify different clusters of performance. Data were collected from 94 male subjects (age: 17.4 ± 0.7 years), competing in a Euroleague Basketball Tournament. Guards covered a greater relative distance than centres and forwards (small to moderate effect). Forwards and guards had more peak accelerations, high accelerations and high decelerations than centres (moderate to large effects). A cluster analysis allowed to classify all cases into three different groups (Lower, Medium and Higher activity demands), containing 37.4%, 52.8% and 9.8% of the cases, respectively. The high accelerations, high decelerations, peak accelerations and total distance covered were the variables that most contributed to classify the players into the new groups. The percentage of cases distributed in the clusters according to playing position, game type (worst vs worst, mixed opposition, best vs best) and team were different. Centres have lower physical demands specially related with the number of accelerations and decelerations at high intensity and the peak acceleration when compared with guards. Each team has a different activity profile, that does not seem to influence the tournament outcome.     

The relationship between functional potential and field performance in elite female wheelchair basketball players

The functional classification system for wheelchair basketball is based on an analysis of the players' functional resources through field-testing and game observation. Under this system, players are assigned a score of 1 to 4.5. The aim of this study was to determine if the wheelchair basketball player classification system reflects the existing differences in performance of elite female players. During the World Championship for Wheelchair Basketball in Sydney 1998, eight teams were videotaped for three 40-min games for a total of 120 min per team. Fifty-nine female players (Class I [1 and 1.5 points] n=12; Class II [2 and 2.5 points] n=20; Class III [3 and 3.5 points] n=13; Class IV [4 and 4.5 points] n=14) were retained for a detailed performance analysis by means of the Comprehensive Basketball Grading System (CBGS). Two-way analysis of variance showed high point players to perform better compared with low point players for the majority of variables determining the quality of game performance. A lack of significant differences between two adjacent classes was explained on the basis of the methodological approach, the class-position relationship in this sample, and the performance level of women's wheelchair basketball. We conclude that the performance of elite female wheelchair basketball players is dependent on functional ability.     

Anthropometric,physiological and maturational characteristics in selected elite and non-elite male adolescent basketball players

Abstract

We investigated the anthropometric, physiological and maturation characteristics of young players (13–14 years old) associated with being successful in basketball. Body parameters were measured (stature, total body mass, skinfolds and lengths) and physiological capacities were assessed by endurance, sprint (20 m), jump and dribbling tests. Chronological age (CA) was recorded and maturity estimated using predicted age at peak height velocity (APHV). Anthropometric analysis indicated that elite players were taller, heavier and had a higher percentage of muscle. Further, physiological testing showed that these elite players perform better in jump, endurance, speed and agility tests (especially in the agility and ball tests). In addition, these skills are correlated with point average during the regular season. More basketball players born in the first semester of the year are selected and there is a predominance of early-maturing boys among those selected for the elite team. Those who are more mature have advantages in anthropometric characteristics and physiological test results. In conclusion, around puberty, physical and physiological parameters associated with maturity and CA are important in determining the success of basketball players. These findings should be taken into account by trainers and coaches, to avoid artificial bias in their selection choices.     

从雅典奥运会看中国男篮的现状与发展趋势

运用文献资料法、观察法、逻辑分析法和数理统计法,对中国男篮在雅典奥运会上的进攻和防守情况进行分析。发现中国队进攻与防守战术方法有待改善、缺少及时的应变办法、内线优势无法充分发挥、忽略整体战略战术与队员个人技术及力量等因素之间的关系。认为中国队存在着内线以及心理方面的优势。提出中国队在以后的发展中应该完善阵容配备和战术打法,形成自己的特色、强化防守、强化全面,加强后卫的培养及时掌握世界篮球发展的趋势等建议。     

The relationship between functional potential and field performance in elite female wheelchair basketball players

The functional classification system for wheelchair basketball is based on an analysis of the players' functional resources through field-testing and game observation. Under this system, players are assigned a score of 1 to 4.5. The aim of this study was to determine if the wheelchair basketball player classification system reflects the existing differences in performance of elite female players. During the World Championship for Wheelchair Basketball in Sydney 1998, eight teams were videotaped for three 40-min games for a total of 120?min per team. Fifty-nine female players (Class I [1 and 1.5 points] n?=?12; Class II [2 and 2.5 points] n?=?20; Class III [3 and 3.5 points] n?=?13; Class IV [4 and 4.5 points] n?=?14) were retained for a detailed performance analysis by means of the Comprehensive Basketball Grading System (CBGS). Two-way analysis of variance showed high point players to perform better compared with low point players for the majority of variables determining the quality of game performance. A lack of significant differences between two adjacent classes was explained on the basis of the methodological approach, the class–position relationship in this sample, and the performance level of women's wheelchair basketball. We conclude that the performance of elite female wheelchair basketball players is dependent on functional ability.     

中、韩男子曲棍球短角球射门技术的运动生物力学分析

为确立较规范的短角球动作技术模式 ,以提高我国男子曲棍球短角球的射门技术水平 ,采用录像解析方法对中、韩两名优秀短角球射手的短角球射门技术进行分析。得出我国运动员在引杆时应注意遵循大关节带动小关节运动的生物力学原理 ;在击球时 ,要保持重心的平稳性