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Israel Halperin Dale W. Chapman Kevin G. Thompson Chris Abbiss 《Journal of sports sciences》2019,37(1):59-66
Prior research indicates that providing participants with positive augmented feedback tends to enhance motor learning and performance, whereas the opposite occurs with negative feedback. However, the majority of studies were conducted with untrained participants performing unfamiliar motor tasks and so it remains unclear if elite athletes completing familiar tasks respond in a similar fashion. Thus, this study investigated the effects of three different versions of false-performance feedback on punching force (N), pacing (force over time) and ratings of perceived exertion (RPE) in 15 elite amateur male boxers. Athletes completed a simulated boxing bout consisting of three rounds with 84 maximal effort punches delivered to a punching integrator on four separate days. Day one was a familiarisation session in which no feedback was provided. In the following three days athletes randomly received false-positive, false-negative and false-neutral feedback on their punching performance between each round. No statistical or meaningful differences were observed in punching forces, pacing or RPE between conditions (P > 0.05; ≤ 2%). These null results could stem from the elite status of the athletes involved, the focus on performance rather than learning, or they may indicate that false feedback has a less potent effect on performance than previously thought. 相似文献
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Israel Halperin Dale W. Chapman David T. Martin Chris Abbiss 《Journal of sports sciences》2017,35(5):500-507
Research indicates that instructing athlete’s to focus on bodily movements (internal focus of attention [IFA]) may hinder performance, whereas instructing them to focus on the movement outcome (external focus of attention [EFA]) often enhances performance. Despite the importance of instructions in striking combat sports, limited research has examined the influence of IFA and EFA on performance in well-trained combat athletes. This study investigated the effects of different instructional cues on punching velocity (m · s?1) and normalised impact forces (N · kg?1) among intermediate (n = 8) and expert (n = 7) competitive boxers and kickboxers. Athletes completed three rounds of 12 maximal effort punches delivered to a punching integrator on three separate days. Day one was a familiarisation session with only control instructions provided. In the following two days athletes randomly received IFA, EFA or control instructions prior to each of the three rounds. Athletes punching with EFA were 4% faster and 5% more forceful than IFA (P < 0.05), and 2% faster and 3% more forceful than control (P < 0.05). Furthermore, experts punched 11% faster and with 13% greater force compared with intermediate athletes (P < 0.05). EFA led to a positive effect on punching performance and should be favoured over IFA and control instructions. 相似文献
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在分析"子"的"时"的含义的基础上,对《日知录》中的一处看法提出了商榷意见;并在汉语历时词汇学的启发下,分析认为:现代汉语的"日子"乃历时上并列短语"日子"通过词汇化降格而来."日子"词汇化的环境和条件为:"日子"作为短语和词之间具有衍生关系,魏晋以降词缀"子"的成熟以及"词根 子(词缀)"这一强势结构对相关词的类化作用;结果:"日子"至宋代就完成了由短语至词的降格,具备了现代汉语"日子"的结构、意义及用法,从而也使人误以为"日子"在历时层面上就是附加式构词. 相似文献
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王倩 《邢台职业技术学院学报》2010,27(5):69-71
本文以板状件冲裁模为例,通过在三维造型软件Pro/E系统中移植eDrawings技术,实现对再生模型进行多项功能的离线演示与其它操作。 相似文献
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分析了冲压等高线与冲压方向的相互关系,归纳出不同冲压方向下冲压等高线的变化规律,进而从图形比较的角度将冲压等高线转化为边心距曲线进行比较,从而建立基于冲压等高线的冲压方向优化模型,为后续进行基于CAD软件的优化计算奠定基础. 相似文献
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以取向硅钢的径向(与轧向分别成0°、25°、45°、55°、70°和90°)拉伸变形行为为案例,探讨影响汽车板深冲性能的因素。结果表明,材料的滑移系和强度是影响其延伸率和深冲性能的两个重要因素。由于具有强烈的γ-纤维织构的汽车板法向强度高、径向强度低,并且各向异性小,延展性好,因此其深冲性能极好。利用X-射线织构分析技术可以较好地评估其深冲性能。 相似文献
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本文通过研究和分析数控冲加工的工艺特点,提出了在冲孔机的程序设计中应当注意的一些事项,将数控冲程序设计在生产过程应用中常见的问题进行剖析,并以相应的实例阐述了完成各项工作和解决具体问题的办法。 相似文献
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针对手表主夹板精冲孔模结构进行改进,并对凸模固定板中少数坐标位置度超差孔进行精度修正,提高了手表主夹板精冲孔模具的冲孔坐标位置度精度及工作稳定性。 相似文献
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在数控冲床加工中,模具的排刀最为重要,是很多工厂都很想解决的问题。若是产品的排刀不合理,容易造成产品带料、跳料、模具偏载、影响生产等现象。产品的合理排刀能节约很多模具成本,关系着产品的质量、交期、成本等问题。主要阐述了通过模具排刀来解决产生偏裁现象的主要问题。 相似文献