Dynamics of the basketball shot with application to the free throw

Abstract

A completely general three-dimensional dynamic model is presented for the motion of basketball shots that may contact the rim, the backboard, the bridge between the rim and board, and possibly the board and the bridge simultaneously. Non-linear ordinary differential equations with six degrees of freedom describe the ball angular velocity and ball centre position. The model includes radial ball compliance and damping and contains five sub-models: purely gravitational flight, and ball – rim, ball – bridge, ball – board, and ball – bridge – board contact. Each contact sub-model has both slipping and non-slipping motions. Switching between the sub-models depends on the reaction force at, and velocity of, the contact point. Although the model can be used to study shots from any point on the court, we here use it to study the sets of free throw release angle, velocity, angular velocity, and lateral deviation angle that result in success (capture), as well as underhand free throws and those using an under-inflated ball. Free throw shots with larger backspin, lower inflation pressures, and underhand release conditions are shown to result in larger capture percentages.     

足球运动员视觉搜索策略研究

足球是一项攻防转换速度非常快的运动项目,良好的预测能力对足球运动员非常重要。足球比赛中,运动员比非运动员有更好的预测能力,这种差异可能是因为在视觉搜索过程中,运动员注意到了关键线索,而非运动员根本没有注视到。本研究通过不同时间阻断点、放映速度的足球罚点球视频分析不同水平运动员的预测能力和中枢资源占用程度,发现在触球瞬间,运动员组预测准确率较非运动组高。通过眼动仪分析视觉停留区域时间序列特征,发现运动员组采用了有规律的视觉搜索模式提取有效特征值进行预测。本研究认为运动员可以通过反复观看和分析不同场景下的比赛过程,提高视觉搜索能力,进而提高预测能力,结果对运动训练实践有一定的现实指导意义。     

信息量与认知负荷对羽毛球运动员视觉搜索特征的影响

选取14名羽毛球专业运动员和14名大学生初学者为被试,以羽毛球专项情境中对手即将回球的动作前情境图片预判为反应任务,探讨被试在不同信息量与认知负荷情况下知觉预判绩效及眼动特征。结果表明:运动员与初学者利用更多的信息来加快动作预判速度;运动员动作预判速度要快于初学者,二者在简单任务中的动作预判准确性优于复杂任务中的预判准确性;信息量主要影响运动员动作预判准确性。运动员视觉搜索的注视时间低于初学者;高信息量注视时间少于低信息量的注视时间,且运动员比初学者注视频率更少。运动员注视次数少于初学者;眼跳距离多于初学者;运动员注视轨迹比初学者更为集中。在视觉搜索分配上,运动员与初学者都主要关注球拍与持拍臂,但是在复杂任务与高信息量中,运动员比初学者更关注场上对手与场地位置关系。     

On the temporal and behavioural consistency of pre-performance routines: An intra-individual analysis of elite basketball players' free throw shooting accuracy

Abstract

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.     

足球运动员进攻战术决策任务下的视觉搜索特征

探讨足球运动员进攻战术决策任务下的视觉搜索特征.以"3V2"进攻战术决策视频为刺激材料,以8名职业联赛预备队队员为专家组,以8名足球专项大学生为新手组,采用德国Ergoneers生产的Dik-ablis Professional头戴式眼动仪配合D-Lab软件进行数据采集与处理,邀请专家采用Likert5点选项法对战术决...     

免费义务教育政策下武术馆校经营状况及发展对策研究

免费义务教育政策在一定程度上影响着武术馆校的发展,也成了研究武术馆校运营的切入点。运用文献资料、问卷调查等方法,对比分析实施免费义务教育前后武术馆校的生源状况、收费状况以及经营内容等的变化,阐述免费义务教育政策对武术馆校经营发展的影响,提出今后武术馆校进行合理化经营的若干建议。     

Especial skill vs. quiet eye duration in basketball free throw: Evidence for the inhibition of competing task solutions

Abstract

The quiet eye (QE) is a gaze phenomenon that has been studied over more than two decades. However, the underlying mechanisms of the well-known expertise effect, namely, longer QE durations in experts when compared to less-skilled athletes remain unclear. Therefore, from a functional perspective, an inhibition hypothesis was proposed that explains long QE durations in experts with increased inhibition requirements over movement parametrisation. This hypothesis was tested by making use of the especial-skill effect in basketball free throw which refers to the observation of higher actual performance than would be predicted on the basis of performance at the nearby locations. In line with the expectations, from the distance of the free-throw line, higher actual than predicted shooting accuracy and longer actual than predicted QE duration were revealed. This suggests that when performing free throws prolonged QE durations are required to shield the optimal against alternative task solutions within the very dense sub-space of this especial skill. These findings suggest an inhibition function of long QE durations in expert athletes.     

Quiet eye training aids the long-term learning of throwing and catching in children: Preliminary evidence for a predictive control strategy

Abstract

Quiet eye training (QET) may be a more effective method for teaching children to catch than traditional training (TT) methods, but it is unclear if the benefits accrued persist in the long term. Thirty children were randomly allocated into a QET or TT group and, while wearing a mobile eye tracker, underwent baseline testing, training and two retention tests over a period of eight weeks, using a validated throw and catch task. During training, movement-related information was provided to both groups, while the QET group received additional instruction to increase the duration of their targeting fixation (QE1) on the wall prior to the throw, and pursuit tracking (QE2) period on the ball prior to catching. In both immediate (R1) and delayed (R2, six weeks later) retention tests, the QET group had a significantly longer QE1 duration and an earlier and longer QE2 duration, compared to the TT group, who revealed no improvements. A performance advantage was also found for the QET compared to the TT group at both R1 and R2, revealing the relatively robust nature of the visuomotor alterations. Regression analyses suggested that only the duration of QE1 predicted variance in catch success post-training, pointing to the importance of a pre-programming visuomotor strategy for successful throw and catch performance.