Kinematic comparison of the seoi-nage judo technique between elite and college athletes

This study sought to identify biomechanical factors that determine fast and skilful execution of the seoi-nage (shoulder throw) technique by comparing kinematics between elite and college judo athletes. Three-dimensional motion data were captured using a VICON-MX system with 18 cameras operating at 250 Hz as three male elite and seven male college judo athletes performed seoi-nage. No significant difference was found in motion phase time of the turning phase between the two groups, indicating that motion phase time is not necessarily a factor contributing quickness in seoi-nage. The maximum relative velocity of the whole body centre of mass along the anterior–posterior direction was significantly greater in the elite athletes (2.74 ± 0.33 m/s) than in the college athletes (1.62 ± 0.47 m/s) during the turning phase (p = 0.023). The overall angular velocity of the body part lines, particularly the arm line, tended to be greater in the elite athletes (p = 0.068). The results imply that the velocity of the thrower relative to the opponent in the forward drive and turning motion reflects high skill seoi-nage. Coaches should recognise the relative forward velocity as a factor that may contribute to a successful seoi-nage when teaching the judo throw technique.     

对我国优秀女子铁饼运动员投掷技术的运动学分析

目前,我国优秀女子铁饼运动员的成绩与世界一流水平相比,存在不少差距。本文将第6届全运会优秀女子铁饼运动员的技术动作分为4个时相,对其运动学特征进行解析,为改进技术动作、提高运动成绩提供参考依据。     

运动技能学的迁移研究与练习法的分类

借鉴国外运动技能学有关迁移的研究结果对我国相对落后的练习法研究具有迫切意义.练习法分类的重要性以及我国当前练习法分类体系所存在的问题,要求我们重新审视练习法分类体系.以运动技能学习的迁移规律作为分类标准,可对练习法进行理想的分类.     

Effects of bilateral and non-dominant practices on the lateral preference in judo matches

This study analysed the effects of bilateral and non-dominant practice on novice practitioners’ lateral preference for judo skills in a combat context (i.e., randori). Thirty sports sciences students (22 men and 8 women; mean age 19 ± 1 years) with right hand, foot, and counterclockwise rotation preferences were divided into 3 groups: bilateral (BG; n = 8), non-dominant (NDG; n = 11), and control (CG; n = 11). Participants received 8 weeks of training at a rate of 3 days per week. The NDG was trained to perform judo skills exclusive with their non-dominant side, while the BG performed every task symmetrically. Before and after training, participants were recorded during two 3-min randoris to obtain the percentage of their engagement in dominant side actions. Pretest percentages were 73.1 ± 19.9%, 77.8 ± 18.8%, and 68.9 ± 27.2% for BG, NDG, and CG, respectively. Post-test values were 75.0 ± 15.6%, 23.3 ± 27.9%, and 72.2.9 ± 20.4%, respectively. Significant differences were observed between NDG and each of the other groups after the training. Changes from pretest were only significant for NDG (P = 0.003). These results suggest that lateral preference among novice judo practitioners during randori can be modulated by the type of practice.     

The effect of consistent and varied follow-through practice schedules on learning a table tennis backhand

In table tennis the follow-through action after a shot is an important part of skill execution. In this experiment, we aimed to extend literature around the contextual interference effect by investigating whether the way the follow-through is organised in practice affects learning of the backhand shot in table tennis. Thirty unskilled participants were allocated to blocked-variable practice, random-variable practice or a control-constant group and aimed backhand shots towards a target following ball projection from a machine. Each group completed these shots in a pre-test, a training phase with follow-through manipulations, a post-test, and a retention test. The random-variable group improved their shot accuracy from pre-test to post-test and from pre-test to retention test (both P < 0.01, d = 1.03), whereas neither the blocked-variable nor the control-constant group displayed any change in shot accuracy. Practising the follow-through in a random-variable fashion enhanced learning of the preceding shot compared with blocked-variable practice or no follow-through instructions. The benefits of learning motor skills under conditions of high contextual interference also apply to how follow-through actions are organised. The findings are valuable to coaches and suggest that instructions related to the follow-through action should be considered as well as the primary skill itself.     

Changes in joint kinetics during learning the longswing on high bar

Biomechanics helps us understand the association between technique changes and performance improvement during learning. The aim of this research was to investigate joint kinetic characteristics of technique during learning of the longswing on the high bar. Twelve male, novice participants took part in the learning study. During swing attempts in 8 weekly testing sessions, kinematic data were collected. Inverse dynamics analysis was performed from known zero forces at the toes to quantify joint moments and power at the hips and shoulders. Key biomechanical constraints that limited performance outcome were identified based on changes in joint kinetics during learning. These constraints were the ability to perform a large shoulder power and to overcome passive kinetics acting during the downswing. Constraints to action at the level of joint kinetics differentially challenge learners and therefore could underpin more individual, specific learning interventions. Functional phases, defined by maximum hyperextension to flexion of the hips and maximum flexion to extension of the shoulders, did not describe the key joint kinetics of the hip and shoulder for novices. The functional phases may serve however to identify novices that were unable to overcome the passive kinetic constraint.     

Self-controlled amount and pacing of practice facilitate learning of a sequential timing task

ABSTRACT

Allowing learners to control the number of practice trials has been shown to facilitate motor learning (Lessa & Chiviacowsky, 2015; Post et al., 2011; 2014). However, it is uncertain the extent to which prior findings were influenced by the combined effects of allowing participants to control both the pacing- and amount-of-practice. The present study examined the independent effects of self-controlled amount- and pacing-of-practice on learning a sequential timing task. Participants were assigned to a self-controlled-amount-of-practice (SCA), self-controlled-pacing-of-practice (SCP), yoked-amount-of-practice (YKA), or a yoked-pacing-of-practice (YKP) group. Participants completed acquisition, immediate retention/transfer and delayed retention/transfer. During acquisition, SCA controlled the number of acquisition blocks completed with a fixed inter-trial interval while SCP controlled the inter-trial interval with a fixed number of blocks. Yoked groups were matched to a self-control counterpart so the amount (YKA) and pacing (YKP) were equivalent. Self-control groups demonstrated lower absolute constant error during immediate-retention and lower absolute constant error and variable error during delayed retention (p < .05). For intrinsic motivation, SCA scored significantly higher than SCP for the subscale Interest/Enjoyment (p < .05). Findings indicated that self-control, regardless of type, facilitated motor learning. Further work is needed to continue to examine the relationship between controlling the amount and pacing of practice on skill acquisition.     

On the role of imagery modalities on motor learning

Abstract

In the present study, we examine specifically how the sensory conditions available during physical practice of a task might influence the subsequent use of motor imagery. First, as a pre-test, participants had to physically reproduce knee joint positions with or without vision. Second, they practised motor imagery (15 and 150 trials) with visual, kinaesthetic or visuo-kinaesthetic imagery. A control group with no imagery was included. Post-tests were then performed 10 min and 24 h after each imagery session in a sensory condition similar to that used in the pre-test. Results showed that efficient motor imagery instructions have to take account of the sensory information available during physical experience of the task: kinaesthetic or visuo-kinaesthetic imagery in a no-vision condition, and visual imagery or, to a lesser extent, visuo-kinaesthetic imagery in a vision condition. Discussion focuses on the role of sensory motor memory on motor prediction to simulate a specific movement, and on the similarities between physical and mental practice in the development of sensory-specific movement representation.     

最后用力阶段髋的稳定性对标枪运动员出手初速度的影响

通过对我国男子优秀标枪运动员最后用力阶段髋关节的运动状态进行测试与比较，发现左、右髋有其自身的运动规律，其稳定性直接影响到标枪的出手效果。     

Biomechanical energetic analysis of technique during learning the longswing on the high bar

Biomechanical energetic analysis of technique can be performed to identify limits or constraints to performance outcome at the level of joint work, and to assess the mechanical efficiency of techniques. The aim of this study was to investigate the biomechanical energetic processes during learning the longswing on the high bar. Twelve male, novice participants took part in a training study. Kinematic and kinetics data were collected during swing attempts in eight weekly testing sessions. Inverse dynamics analysis was performed from known zero forces at the toes. Joint work, total energy, and bar energy were calculated. Biomechanical constraints to action, that is, limits to novice performance, were identified as “total work” and “shoulder work”. The most biomechanically efficient technique was associated with an onset of the hip functional phase and joint work that occurred between 10–45° before the bottom of the swing. The learning of gross motor skills is realised through the establishment of a set of techniques with task specific biomechanical constraints. Knowledge of the biomechanical constraints to action associated with more effective and efficient techniques will be useful for both assessing learning and establishing effective learning interventions.     

论社会实践在高等体育教育中的地位与作用

通过社会实践对高等体育教育的导向作用,论述与分析了社会实践对人才培养的意义和作用,即:拓宽学生的知识面,培养管理能力及社交能力,扩大教育领域等.     

反馈频率对追踪任务技能学习影响的实验研究

采用单维电脑追踪任务,探讨反馈频率对追踪任务技能学习的影响作用.48名右利手的在校大学生随机分为4组(每组男、女各6人),分别按反馈次数占总练习次数比例的25%、50%、75%、100%的频率方式向各组受试者提供当前反馈.结果显示:①获得阶段,频繁反馈有利于提高操作绩效;②保持阶段,减少反馈频率有利于简单追踪任务技能学习.结论:①当前反馈对于练习者学习动作技能具有很强的指导作用,并且容易使学习者对反馈产生依赖性;②通过减少反馈频率的方式可以减少学习者对反馈的依赖作用;③追踪任务技能学习过程中存在反馈频率适宜值.     

沈阳体育教育专业网球专修学生发球技术学习情况的调查与分析

采用文献资料法、问卷调查法及数理统计法等,对沈阳体育学院体育教育系07、08级网球专修学生发球技术存在的问题进行调查与分析,结果表明：部分网球专修学生的引拍动作不规范;产生的原因主要是由于动作概念不清和身体素质较差,尤其是腹背肌力量、上肢力量及协调性差。     

Helping coaches apply the principles of representative learning design: validation of a tennis specific practice assessment tool

Representative Learning Design (RLD) is a framework for assessing the degree to which experimental or practice tasks simulate key aspects of specific performance environments (i.e. competition). The key premise being that when practice replicates the performance environment, skills are more likely to transfer. In applied situations, however, there is currently no simple or quick method for coaches to assess the key concepts of RLD (e.g. during on-court tasks). The aim of this study was to develop a tool for coaches to efficiently assess practice task design in tennis. A consensus-based tool was developed using a 4-round Delphi process with 10 academic and 13 tennis-coaching experts. Expert consensus was reached for the inclusion of seven items, each consisting of two sub-questions related to (i) the task goal and (ii) the relevance of the task to competition performance. The Representative Practice Assessment Tool (RPAT) is proposed for use in assessing and enhancing practice task designs in tennis to increase the functional coupling between information and movement, and to maximise the potential for skill transfer to competition contexts.     

高师体育专业学生LTT三级培养模式的实践与研究

近年来,国内外学者对高等师范实习教育进行了一定的研究,对体育专业实习教育也有相关分析,但大都将其认同于毕业前教育实习的范畴,本文收集了一定文献资料,运用数理统计等研究方法,结合重庆师专特点,构建体育专业学生“教学见习→试教→教育实习”(即 L-T-T)三级实习教育培养模式,延伸了实习教育的内涵,以适应当前的教育形式和21世纪对体育人才的要求。     

任务性质、观察学习和身体练习比例对运动技能学习的影响

观察使用计算机追踪任务探讨任务性质、观察学习和身体练习比例对运动技能学习的影响。72名受试划分为开放性任务学习组和封闭性任务学习组,然后再根据观察学习+身体练习比例将受试随机分为25%观察学习+75%身体练习组、50%观察学习+50%身体练习组、以及75%观察学习+25%身体练习组,进行为期3 d的计算机追踪任务学习。第3 d学习结束后,对所有受试进行即刻测试2、4 h后保持测试和迁移测试。结果显示:对于封闭性任务技能学习而言,50%观察学习+50%身体练习的比例所获得的学习效果好于25%观察学习+75%身体练习的比例和75%观察学习+25%身体练习的比例;对于开放性任务技能学习而言,25%观察学习+75%身体练习的比例所获得的学习效果好于75%观察学习+25%身体练习的比例;使用相同比例条件下,封闭性任务技能的学习效果好于开放性任务技能。     

Task complexity and sources of task-related information during the observational learning process

Abstract

Although research has examined the influence of various sources of task information for skill acquisition during observational learning, the results have been ambiguous. The purpose of this study was to examine sources of information in relation to the type of task. One hundred and twenty participants were randomly assigned to one of two sets of six treatment strategies: (1) all model demonstrations; (2) model demonstrations with physical practice with knowledge of performance; (3) model demonstrations with physical practice without knowledge of performance; (4) physical practice without knowledge of performance; (5) physical practice with knowledge of performance; or (6) verbal instructions only. One set learned a simple version of the task while the other set learned a more complex version. Cognitive representation and performance accuracy (spatial and temporal) were assessed. Results indicate that task type does influence the source of information to facilitate skill acquisition. The simple task benefited from model demonstrations, physical practice with knowledge of performance, or a combination of model demonstrations and practice both with and without knowledge of performance, while the complex version benefited more from a combination of model demonstrations and knowledge of performance practice. The results of this study provide an insight into the ambiguity that exists within the observational learning and motor learning literature regarding the effectiveness of information sources for motor skill acquisition.     

运动技能学习的结构与本质特征探究

结合运动技能学习的相关理论,研究对运动技能学习的结构进行了探究,发现运动技能学习既包含有运动技术和运动技能两个目标要素的目标结构,还包含有动力、操作和知识三个过程要素的过程结构,两者紧密结合共同反映着运动技能学习的本质特征,也就是以学习运动技术,培养运动能力为核心的教学/训练活动,教师/教练是运动技能学习的主导,学生是学习运动技能的主体,在相关过程要素的影响下,主体的认知结构会随着学习策略应用能力的不断提高而不断完善,从而获得个体运动技能的内化与发展。     

任务难度和学习目标对学习动机的影响

通过对体育课堂中学生投入意愿数据的统计分析,在探讨体育课堂中不同的学习目标对学习动机的影响以及在不同的学习目标情境中,任务难度对学生学习动机的影响,验证了培养学生对体育本身内在而持久的学习动机的重要性.     

任务复杂程度对反馈频率适宜值的影响研究

采用单维简单和两维复杂电脑追踪任务,探讨任务复杂程度对反馈频率适宜值的影响.96名右利手的在校大学生随机分为简单任务和复杂任务组(每组男、女各24名).两组受试者分别在25%相对频率(提供反馈的练习次数占总练习次数的25%,简称反馈频率,下同)、50%反馈频率、75%反馈频率、100%反馈频率条件下,连续两天练习简单或复杂任务,每天练习36次.第2天练习结束后休息10min,2组受试者进行无反馈保持测试.一天后,再进行无反馈的保持测试.结果显示:(1)练习阶段,两组受试者的操作绩效随反馈频率增加呈提高趋势;(2)50%反馈频率利于简单任务的技能学习,75%反馈频率利于复杂任务的技能学习;(3)任务复杂程度与反馈频率适宜值存在交互作用,与简单任务相比,操作复杂任务时,应增加反馈的频率.以上结果提示:当信息加工负荷较小(如操作任务较简单)时,减少反馈频率利于技能学习;而当信息加工负荷较大(操作任务较复杂)时,频繁反馈利于技能学习.