Background and Study Aim. Movement variability is one of the fundamental topics concerning the control of human movement. In recent years, researches have focused on various aspects of variability, which has changed the noise to useful variable on human movement. Present study investigated movement variability level in high skilled dart players that repeated throws over many years. Material and Methods. Seven experienced dart players (three women and four men) were threw 36 darts in three sets (each set 12 throws) from a standard distance (2.37 meters), while the kinematic features of the shoulder, elbow, and wrist were recorded during the throws. Qualisys motion capture system with six cameras was used to record the kinematics of the elbow. Results: entropy analysis revealed that greater variability in movement angle, velocity and acceleration resulted in better dart throwing performance but after reach to this level, throw variability was decreased. The remarkable point in these findings was that variability was constant across all samples despite the varied range of experience in throwing darts from 2.37 meters distance. Entropy analysis showed that in the throws of highly experienced individuals, variation led to greater throwing efficiency. Conclusions: these findings suggest that variability in a throwing activity, which revealed that moderate movement variability results in optimal throwing performance when dart throw has massive amount of practice during many years.

中文翻译：

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在大规模练习飞镖时，适度的运动可变性是最佳的

背景和研究目标。运动可变性是与控制人类运动有关的基本主题之一。近年来，研究集中在可变性的各个方面，这已将噪声变成对人类运动有用的变量。目前的研究调查了高技能的飞镖运动员在多年反复投掷后的动作变异性水平。材料与方法。七名经验丰富的飞镖运动员（三名女子和四名男子）从标准距离（2.37米）以三组（每组12掷）投掷了36支飞镖，同时在投掷过程中记录了肩膀，肘部和腕部的运动学特征。Qualisys运动捕捉系统带有六个摄像头，用于记录肘部的运动学信息。结果：熵分析显示，运动角度的变化更大，速度和加速度导致更好的飞镖投掷性能，但达到此水平后，投掷变化性降低。这些发现的显着点是，尽管从2.37米的距离投掷飞镖的经验范围各不相同，但所有样本的变异性都是恒定的。熵分析表明，在经验丰富的个人掷球过程中，变异导致更高的掷球效率。结论：这些发现表明投掷活动存在可变性，这表明当多年进行大量飞镖投掷时，适度的运动可变性可导致最佳的投掷性能。这些发现的显着点是，尽管从2.37米的距离投掷飞镖的经验范围各不相同，但所有样本的变异性都是恒定的。熵分析表明，在经验丰富的个人掷球过程中，变异导致更高的掷球效率。结论：这些发现表明投掷活动存在可变性，这表明当多年进行大量飞镖投掷时，适度的运动可变性可导致最佳的投掷性能。这些发现的显着点是，尽管从2.37米的距离投掷飞镖的经验范围各不相同，但所有样本的变异性都是恒定的。熵分析表明，在经验丰富的个人掷球过程中，变异导致更高的掷球效率。结论：这些发现表明投掷活动存在可变性，这表明当多年进行大量飞镖投掷时，适度的运动可变性可导致最佳的投掷性能。