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11.
Vanda Correia Duarte Araújo Keith Davids Orlando Fernandes Sofia Fonseca 《Psychology of sport and exercise》2011,12(6):662-669
Background and objective
Field invasion games, such as rugby union, can be conceptualised as dynamic social systems in which the agents continuously interact to contest ball possession and territorial gain. Accordingly, this study aimed to identify the collective system dynamics of rugby union phases-of-play near the try line by investigating whether ball displacement trajectory on the playing field provides insights on successful team performance.Methods
Five rugby union matches were videotaped involving teams at a national league performance level. From these matches, 22 second phases-of-play were selected and digitized for analysis. The variable “distance gained” was investigated as a potential coordination variable describing functional coordination between players and teams. This variable concerned the distance between ball initial position and ball current position over time and was used to define the degree of territory gained by an attacking team.Results
Analysis of distance gained dynamics in attacking sub-phases demonstrated the intermittent character of rugby union performers displacement trajectories on the playing field. Amplitude of ball movements was revealed as a distinguishing feature related to attacking effectiveness. Successful attacking phases displayed lower distances of positional retreat, with the maximum retreat distance achieved sooner in successful compared to unsuccessful phases-of-play. Autocorrelation and ApEn analyses suggested low system variability within time series data concerning both performance outcomes. However, evidence of less regularity and more complexity was found in unsuccessful phases-of-play.Conclusion
Results suggested that distance gained dynamics manifests a characteristic collective behaviour pattern that captures the macroscopic functional order of multi-player attack–defence systems in team sports like rugby union. 相似文献12.
Availability of advance visual information constrains association-football goalkeeping performance during penalty kicks 总被引:1,自引:0,他引:1
A pressing concern within the literature on anticipatory perceptual-motor behaviour is the lack of clarity on the applicability of data, observed under video-simulation task constraints, to actual performance in which actions are coupled to perception, as captured during in-situ experimental conditions. We developed an in-situ experimental paradigm which manipulated the duration of anticipatory visual information from a penalty taker's actions to examine experienced goalkeepers' vulnerability to deception for the penalty kick in association football. Irrespective of the penalty taker's kick strategy, goalkeepers initiated movement responses earlier across consecutively earlier presentation points. Overall goalkeeping performance was better in non-deception trials than in deception conditions. In deception trials, the kinematic information presented up until the penalty taker initiated his/her kicking action had a negative effect on goalkeepers' performance. It is concluded that goalkeepers are likely to benefit from not anticipating a penalty taker's performance outcome based on information from the run-up, in preference to later information that emerges just before the initiation of the penalty taker's kicking action. 相似文献
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14.
Movement organization of cricket batters' actions was analyzed under three distinct experimental task constraints: a representative condition of a practice context in which the batters batted against a "live" bowler, a ball projection machine, and a near life-size video simulation of a bowler. Results showed that each distinct set of task constraints led to significant variations in the patterns of movement control. Removal of advanced information sources from a bowler's actions when the batters faced the ball projection machine caused significant delays in movement initiation, resulting in reduced peak bat swing velocities and a reduction in the quality of bat-ball contact, when compared with batting against a "live" bowler. When responding to a two-dimensional video simulation, batters were able to use information from the bowlers' action, enabling fidelity of initial behavioral responses consistent with the task of batting against a "live" bowler. However, without interceptive task requirements or actual ball flight information, significant variations in downswing initiation timing and peak bat velocities were demonstrated. Findings stress the need for representative experimental and learning designs in fast ball sports for developing performers. 相似文献
15.
The question addressed in this study was the effects of the manipulation of the informational constraints of practice conditions on the acquisition of one-handed catching skill. Three groups of poor catchers (8 participants per group) practiced in either a normal-light, ball-only, or interspersed ball-only and normal-light condition (N = 450 trials). All groups exhibited a significant improvement in the number of catches and catching score and a reduction in the number of misses by the end of practice. The structural organization of the practice conditions had a significant effect on catching performance. Practicing in the interspersed condition had a positive residual effect on subjects' performance in normal light. Similarly, there was a positive residual effect of practicing in the ball-only and the interspersed conditions on subjects' normal-light, posttest performance. The findings are interpreted as support for the argument that practicing under varying informational constraints can benefit skill acquisition by directing the subjects' search toward relevant sources of information. 相似文献
16.
More than 20 years ago, Swenson (1988) proposed and elaborated the Law of Maximum Entropy Production (LMEP) as the missing piece of physical or universal law that would account for the ubiquitous and opportunistic transformation from disordered, or less ordered, to more highly ordered states. Given Boltzmann's (1974) interpretation, the Second Law of Thermodynamics has generally been interpreted as a “law of disorder.” Schrödinger (1945) and Bertalanffy (1952) had shown, however, that the Second Law, viewed from the classical perspective of Clausius (1865) and Thomson (1852), was not anathema to order. Ordered flow, including life, was permissible as long as it produced enough entropy to compensate for its own internal entropy reduction. The central problem remained, however: If the spontaneous production of order was “infinitely improbable,” as Boltzmann had surmised, then why were ordered systems such a fundamental and characteristic property of the visible world? LMEP provided the answer: Order production is inexorable because order produces entropy faster than disorder. In Swenson (1989d), LMEP was given expression as a precise law that could be demonstrated in falsifiable, experimental, physical terms. In Swenson and Turvey (1991), LMEP was tied explicitly to the progressive emergence of living things with their perception–action capabilities. 相似文献
17.
Pamela Naidoo Geri Donenberg Alicia Davids Kim Jonas Redwaan Vermaak Leickness Simbayi 《Journal of Psychology in Africa》2013,23(3):232-240
This study explored South African adolescents’ perceived risk and protection for HIV infection. Adolescents (N=28) with a mean age of 14.6 years receiving mental health care participated in Focus Group Discussions (FGDs) to engage in an in-depth exploration of their perceived risk and protective mechanisms for HIV prevention. The data were analysed using thematic content analysis. Themes that emerged from the FGDs associated with risk for HIV infection were: Alcohol and illicit drug use; Non-condom use; Prostitution and risky sexual activity with multiple partners; and Non-disclosure of HIV status. Themes that emerged as protective mechanisms included: HIV knowledge and appropriate HIV risk reducing behaviour; and Proactive parental attitudes and behaviour. These findings highlight the importance of ascertaining the perceptions of adolescents about risk and protection from HIV infection in order to inform future programs for HIV prevention among adolescents. 相似文献
18.
Kelso, Southard, and Goodman (1979) and Marteniuk and MacKenzie (1980) have each proposed a different theoretical model for bimanual coordination. In the model of Kelso et al., a close temporal relationship between the hands in a bimanual task is predicted, even when each hand is required to move different distances. In Marteniuk and MacKenzie's model, separate motor commands are issued so that each limb will arrive simultaneously at the specified movement endpoint, leading to low temporal associations between limbs. In most previous work on bimanual coordination, manual aiming tasks with differing constraints have been used by subjects in individual studies. In this study, the usefulness of existing models for predicting performance in a real-world catching task in which the required movement pattern was constrained by ball flight characteristics was examined. Eleven university students caught tennis balls with both hands in the following 3 conditions: Condition 1. Ball projected to the right shoulder area (left hand moved a greater distance than the right); Condition 2. Ball projected to center of the chest area, (both hands moved same distance); and Condition 3. Ball projected to left shoulder area (right hand moved a greater distance). Kinematic data (time to peak velocity, movement initiation time) indicating significant cross-correlations between the left and right limbs in all 3 conditions concurred with the data of Kelso et al. (1979) on manual aiming. Timing appeared to be an essential variable coordinating bimanual interceptive actions. Although the limbs moved at different speeds when each was required to move different distances, times to peak velocity showed strong associations, suggesting the presence of a coordinative structure. 相似文献
19.
Body dissatisfaction and eating disorder symptomatology were examined in bisexual individuals (n?=?139 women, n?=?37 men) and compared to lesbian/gay (n?=?51 women, n?=?96 men) and heterosexual individuals (n?=?82 women, n?=?34 men) in a U.S. online sample. Age, body mass index (BMI), income, and exercise frequency served as covariates. MANCOVA results showed a significant gender by sexual orientation interaction and significant main effects of gender and sexuality. Univariate tests were used to explore multivariate results. ANCOVA results for body dissatisfaction showed a significant gender by sexual orientation interaction. Post-hoc comparisons revealed higher levels of body dissatisfaction among all groups compared to heterosexual men. ANCOVA results for eating disorder symptomatology showed a significant main effect of sexual orientation. Post-hoc comparisons revealed higher levels of eating disorder symptoms among bisexual compared to heterosexual individuals. For bisexual men, gay community involvement, maladaptive social comparison, drive for muscularity, self-esteem, gender role orientation, and body dissatisfaction were explored as predictors of eating disorder symptomatology while controlling for age, BMI, exercise frequency, and income in a hierarchical regression analysis. The same factors, minus body dissatisfaction, were explored as predictors of body dissatisfaction in bisexual men. For bisexual women, similar factors, with the exception of drive for muscularity, were explored. Drive for muscularity predicted body dissatisfaction and exercise frequency predicted eating disorder symptomatology in bisexual men. BMI and self-esteem predicted body dissatisfaction in bisexual women; gay community involvement and body dissatisfaction predicted eating disorder symptomatology. 相似文献
20.
This study investigated how novices re-organized motor system degrees of freedom when practicing a multi-articular discrete kicking task. Four male participants practiced a soccer chipping task to seven different target positions over 12 sessions for 4 weeks. Data from each participant indicated changes in degrees of freedom involvement as a function of practice. Further, each participant showed a different progression of change in levels of joint involvement for hip, knee and ankle in the kicking limb. Cross-correlations between joints in the kicking limb also showed different pathways of coupling and de-coupling with practice. Performance outcome scores improved and variability of intra-limb coordination decreased as a consequence of practice for all participants. Angle-angle plots also showed qualitative changes in intra-limb coordination between early and late practice sessions. Evidence suggested that foot velocity at ball contact was functionally manipulated by participants when kicking to target positions with varying height and distance constraints. Referencing data to a model of learning [Newell, K. M. (1985). Coordination, control and skill. In: Goodman, D., Franks, I., & Wilberg, R.B. (Eds.), Differing perspectives in motor learning, memory, and control. Amsterdam: North-Holland, pp. 295-317] determined that progression through different stages of learning may not be sequential and could alternate between learning stages. The present study highlighted individual differences in acquisition of coordination and control of joint motion even under similar task constraints, showing how degeneracy in movement systems facilitates learning. 相似文献