How do technique and coordination change during learning of a whole-body task: Application to the upstart in gymnastics

ABSTRACT

When learning swinging skills on a bar there has been conflicting advice in the research literature regarding whether to coach the “gold standard” technique to novices. The present study aimed to determine how technique (joint angle time histories) and (inter-limb) coordination changed as novice gymnasts learned a fundamental gymnastics skill (the upstart). It was hypothesised that both technique and coordination would become more like an expert as learning progressed. Eight novice gymnasts, unable to perform an upstart, underwent four months of training, with the number of successful upstarts out of 10 recorded at the start and then every month subsequently. In the first and last sessions motion capture was used to determine joint kinematics. Root mean squared differences for the joint angle time histories and continuous relative phase at the shoulder and hip were calculated between the novices and an expert gymnast. As training progressed technique and coordination became more like the expert gymnast. The more successful novices were better able to time their actions within the swing than the less successful novices. Gymnastics coaches teach towards a “gold standard” technique since being successful at the skill is not the only goal, as considerations for future skill development are made.     

The influence of the vaulting table on the handspring front somersault

The traditional “horse” was replaced by a new vaulting “table” in artistic gymnastics competitions in 2001.The aim of this study was to determine whether the table led to a change in vaulting technique. This was achieved by comparing three-dimensional video-based analyses (50 Hz) of selected biomechanical discrete and continuous variables across four elite male gymnasts performing a series of handspring front somersault vaults on the traditional horse and the new table. Individual joint and inter-segment coupling (continuous relative phase) were used to quantify techniques used on the two apparatuses. Differences were attributed in part to the design and construction of the new table. No differences were observed for the approach and take-off from the board. Significant differences in hip flexion at board take-off and strike angle on the table were observed. One of the effects of the latter was an increase in vertical take-off velocity compared with the horse. Individual strategies were observed in hip and shoulder coordination patterns that were obscured when group data were considered. Close monitoring of the evolution of skill on this new apparatus is paramount for gymnastics coaching, and further studies of current elite competitive vaulting techniques are required.     

A multi-component assessment model for monitoring training distress among athletes

Abstract

We report the initial validation of a multi-component assessment model for monitoring training distress among athletes. The model combines measures of mood disturbance with measures of perceived stress and symptom intensity. Altogether, 492 athletes completed the 10-item Perceived Stress Scale (PSS-10; Cohen et al., 1983), the 24-item Brunel Mood Scale (BRUMS; Terry et al., 2003), and a checklist of 19 symptoms associated with acute overtraining (Fry et al., 1994). Six training distress factors were identified by an exploratory factor analysis: “depressed mood”, “perceived vigour”, “physical symptoms”, “sleep disturbance”, “perceived stress”, and “general fatigue”. Comparisons of group means of these factors with a previously validated inventory were consistent with theoretical predictions and provided evidence of construct validity. Internal consistency of the subscales was also confirmed, with Cronbach alphas ranging from 0.72 to 0.86. Together, these findings suggest that this multi-component model provides a sound conceptual basis for the assessment of training distress among athletes.     

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.     

The relationship between shoulder alignment and elbow joint angle in cricket fast-medium bowlers

Abstract

The aim of this study was to examine the relationship between shoulder alignment and elbow angle during the delivery action of fast-medium bowlers. The elbow and upper trunk alignment were recorded for 13 high-performance bowlers (mean age 20 years) using a 12-camera Vicon motion analysis system operating at 250 Hz. The three highest velocity trials for “good” and “short” length deliveries were analysed. Results showed that bowlers with a more front-on shoulder alignment at back-foot impact and when the upper arm was horizontal to the ground experienced a significantly greater elbow flexion – extension range when compared with those who had a more side-on orientation at the same point in the delivery action. Bowlers with greater shoulder counter-rotation also recorded higher elbow flexion and subsequently extension during the period from upper arm horizontal to ball release. Shoulder alignment and elbow angles were similar for “short” and “good” length deliveries. It was concluded that bowlers with a more front-on shoulder orientation at back-foot impact demonstrated a higher elbow extension from upper arm horizontal to ball release and are therefore more likely to infringe International Cricket Council elbow tolerance levels, compared with those who adopt a more side-on shoulder orientation at back-foot impact.     

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.     

等速康复训练在集体小球项目中的应用研究

对2007-2012年间广东省集体小球类项目(手球、曲棍球、垒球)运动损伤后等速肌力康复效果进行归纳总结。应用等速肌力测试系统为广东集体小球项目运动员提供了419人次5 872关节次等速康复训练,康复前后进行角速度为60°/s的膝、肩关节等速肌力测试,以及角速度为30°/s的踝关节等速肌力测试,结果发现:(1)膝关节损伤发生率最高,达到60.88%,踝、肩也是损伤多发部位,整体看来,下肢损伤发生率高于上肢。(2)各项目运动员经过一段时间的等速康复训练后,关节等速肌力得到显著提高。结论:(1)在集体小球项目中,运动损伤发生部位与运动专项特点密切相关,损伤发生率从高到低依次为膝、踝、肩、腰背、髋。(2)等速肌力康复作为一种康复手段,在集体小球项目运动员运动损伤过程中效果明显,提供了客观可靠的量化指标。     

运动性疲劳对横踢技术动作特征及其击打速度的影响研究

探究高水平跆拳道运动员身体出现不同量度的运动性疲劳时,横踢技术动作特征出现的差异及其对击打速度产生的影响程度。对20名跆拳道运动员采用Excalibur Sport cycle ergometer功率自行车进行诱导疲劳和YSI 1500 SPORT乳酸测试仪测定疲劳程度并划分为轻度、中度、重度三个量度;运用VICON Nexus三维系统捕捉横踢技术的运动轨迹,运用VICON Polygon软件将运动轨迹划分为启动、击打、回收三个时段进行分析。结果显示：启动时段三种疲劳的动作时间为：轻度疲劳0.25 s < 中度疲劳0.27 s < 重度疲劳0.29 s;击打时段的动作速度为：轻度疲劳12.20 m/s > 中度疲劳11.75 m/s > 重度疲劳10.64 m/s;横踢技术在回收时段的启动和加速过程中,三种类型之间的动作特征所表现出来的差异存在显著性（p<.05）。运动性疲劳的量度对横踢技术动作特征及其击打速度的影响较为显著。运动性疲劳的量度越大,技术动作的稳定性相对较差,鞭打动作形式也相对较差,对动作特征和击打速度的影响程度也越大;运动性疲劳的量度随着体内乳酸含量的变化而发生改变,乳酸峰值出现的时间节点是反映身体重度疲劳的时间节点,同时也是教练员合理调整技战术,通过消除疲劳的方式,减小对技术动作影响的重要节点。     

国家队激流回旋运动员肩关节脱位的分析研究

通过对国家队激流回旋运动员损伤状况的检查和治疗发现 ,肩关节脱位发生率比较高 ,女性高于男性 ;肩关节脱位与肩周围软组织损伤密切相关 ;“爱斯基摩翻滚”是导致肩关节脱位的主要技术动作。据此 ,提出了 4项建议     

Evolution of muscular fatigue in periscapular and rotator cuff muscles during isokinetic shoulder rotations

To this day, how shoulder muscles react to a strong fatigue stimulus during dynamic shoulder rotations remains unknown. The aims of this study were to assess the effect of repeated maximal internal-external isokinetic shoulder rotations on shoulder strength and muscle activity. Twenty-four individuals completed a 50-repetition fatiguing isokinetic protocol while electromyography was recorded on eleven muscles of the shoulder girdle. Time-frequency transformation and an ANOVA model using statistical parametric mapping methods were used to analyze shifts in instantaneous median frequency (MDF) between each 10-repetition Blocks. Peak torques decreased in both internal and external rotation (P < 0.01) by 24.8% on average which indicated the presence of fatigue. Significant decrease in MDF (P < 0.01) was observed for pectoralis, middle deltoid, upper, middle and lower trapezius, infraspinatus and subscapularis muscles. The observed fatigue to the periscapular and rotator cuff muscles suggests that shoulder stability could be compromised during repeated shoulder rotations, which could underlie the increased risk of scapular dyskinesis and shoulder impingement during fatiguing tasks. The present study provides a deeper understanding on the manifestations of fatigue within muscles of the shoulder girdle and the results could be applied toward improvements in athlete shoulder injury prevention and rehabilitation programs.     

The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.     

Examining coaches’ perceptions of how their stress influences the coach–athlete relationship

This study extends recent coach stress research by evaluating how coaches perceive their stress experiences to affect athletes, and the broader coach–athlete relationship. A total of 12 coaches working across a range of team sports at the elite level took part in semi-structured interviews to investigate the 3 study aims: how they perceive athletes to detect signals of coach stress; how they perceive their stress experiences to affect athletes; and, how effective they perceive themselves to be when experiencing stress. Following content analysis, data suggested that coaches perceived athletes able to detect when they were experiencing stress typically via communication, behavioural, and stylistic cues. Although coaches perceived their stress to have some positive effects on athletes, the overwhelming effects were negative and affected “performance and development”, “psychological and emotional”, and “behavioural and interaction” factors. Coaches also perceived themselves to be less effective when stressed, and this was reflected in their perceptions of competence, self-awareness, and coaching quality. An impactful finding is that coaches are aware of how a range of stress responses are expressed by themselves, and to how they affect athletes, and their coaching quality. Altogether, findings support the emerging view that coach stress affects their own, and athlete performance.     

Analgesics use in competitive triathletes: its relationship to doping and on predicting its usage

The two major objectives of this study were (i) to assess variables that predict the use of analgesics in competitive athletes and (ii) to test whether the use of analgesics is associated with the use of doping. A questionnaire primarily addressing the use of analgesics and doping was distributed among 2,997 triathletes. Binary logistic regression analysis was performed to predict the use of analgesics. Moreover, the randomised response technique (RRT) was used to estimate the prevalence of doping in order to assess whether users of analgesics have a higher potential risk for doping than non-users. Statistical power analyses were performed to determine sample size. The bootstrap method was used to assess the statistical significance of the prevalence difference for doping between users and non-users of analgesics. Four variables from a pool of 16 variables were identified that predict the use of analgesics. These were: “version of questionnaire (English)”, “gender (female)”, “behaviour in case of pain (continue training)”, and “hours of training per week (>12 h/week)”. The 12-month prevalence estimate for the use of doping substances (overall estimate 13.0%) was significantly higher in athletes that used analgesics (20.4%) than in those athletes who did not use analgesics (12.4%). The results of this study revealed that athletes who use analgesics prior to competition may be especially prone to using doping substances. The predictors of analgesic use found in the study may be of importance to prepare education material and prevention models against the misuse of drugs in athletes.     

Shoulder 3D range of motion and humerus rotation in two volleyball spike techniques: injury prevention and performance

Repetitive stresses and movements on the shoulder in the volleyball spike expose this joint to overuse injuries, bringing athletes to a career threatening injury. Assuming that specific spike techniques play an important role in injury risk, we compared the kinematic of the traditional (TT) and the alternative (AT) techniques in 21 elite athletes, evaluating their safety with respect to performance. Glenohumeral joint was set as the centre of an imaginary sphere, intersected by the distal end of the humerus at different angles. Shoulder range of motion and angular velocities were calculated and compared to the joint limits. Ball speed and jump height were also assessed. Results indicated the trajectory of the humerus to be different for the TT, with maximal flexion of the shoulder reduced by 10 degrees, and horizontal abduction 15 degrees higher. No difference was found for external rotation angles, while axial rotation velocities were significantly higher in AT, with a 5% higher ball speed. Results suggest AT as a potential preventive solution to shoulder chronic pathologies, reducing shoulder flexion during spiking. The proposed method allows visualisation of risks associated with different overhead manoeuvres, by depicting humerus angles and velocities with respect to joint limits in the same 3D space.     

乒乓球运动员肩关节损伤原因及预防对策

肩关节损伤在乒乓球运动损伤中最为常见,损伤不仅影响运动员运动成绩的提高、运动寿命的减短,甚至给运动员的生理、心理造成严重的影响。本文分析了乒乓球运动员肩关节损伤的原因,并相应提出有效的预防措施,旨在为保证训练的正常进行及提高运动员的运动寿命提供参考。     

Effects of volleyball match-induced fatigue on knee joint position sense

Abstract

It has been suggested that a greater number of injuries during the last third of practice sessions or matches could be related to alteration of lower limb neuromuscular control due to neuromuscular fatigue. This fatigue-related effect can be mediated by changes in joint proprioception. In athletes, the use of functional fatigue protocols could have the advantage of mimicking the demands of sporting activity, thus reflecting more specifically the changes in neuromuscular control and proprioception observed in sport settings. The purpose of the present study was to assess the effect of fatigue induced by a volleyball match on knee joint position sense in elite volleyball players. Seventeen female volleyball players aged 18.9±4.2 years from the Portuguese national team volunteered for the study. Knee joint position sense was evaluated by an open kinetic chain technique and active knee positioning, and was reported using absolute, relative, and variable angular errors. Joint position sense measures were obtained before and immediately after a simulated volleyball match of five sets. To ensure that the match was sufficiently intense to induce fatigue, the perceived exertion or exercise intensity was assessed at the end of the match using Borg’ s rating of perceived exertion (RPE) scale. All participants completed the volleyball match (90min duration), reaching or exceeding 15 on the RPE scale (15.59±0.71; range 15–17), equivalent to “hard/heavy work”. After the volleyball match, a significant increase in absolute (2.11°) and relative (1.71°) angular errors was detected. Match-induced fatigue significantly exacerbated the overestimation of the test position. Moreover, the reliability and accuracy in estimating knee angles decreased from rest to the fatigued state, as shown by the increase (264%) in variable error. Our results show that fatigue induced by a volleyball match has a marked effect on knee joint position sense in elite female volleyball players. Knee joint position sense was less accurate and less consistent after the volleyball match. Fatigue induced by a simulated competitive volleyball match resulted in proprioceptive deficits, decreasing sensorimotor system acuity in female volleyball players.     

我国优秀女子铅球运动员巩立姣最后用力技术的运动学分析

选定进入2013年全国田径大奖赛（苏州站）女子铅球决赛运动员巩立姣最后用力阶段技术为研究对象,研究结果显示：右侧技术中,右踝关节蹬伸比较积极,右膝角幅度大整个右侧各关节伸展比较充分;左侧技术中,左膝角偏小,蹬伸幅度、左膝关节缓冲幅度与世界优秀运动员一致;最后用力阶段各环节特征技术中,左脚着地瞬间身体重心速度、右髋速度、右肩速度都低于3位优秀运动员,而铅球出手瞬间右肩速度、右肘速度较强,另外最后用力出手瞬间,出手高度和出手速度都低于我国3位世界级优秀运动员相应指标。     

男子标枪运动员“第二支撑制动现象”的运动学特征分析

借助KS— 16mm高速摄影机 ,对我国第五届大学生运动会前 8名男子标枪运动员最后用力双支撑阶段的投掷动作进行了拍摄。研究结果 :把髋理解为“第二支撑制动环节” ,有助于对该环节的重视 ,更有助于了解其在最后用力过程中产生制动所发挥的作用。“第二支撑制动现象”的出现 ,对上肢的“鞭打”动作 (投掷效果 )有着直接的影响     

The off-break and “doosra”: Kinematic variations of elite and sub-elite bowlers in creating ball spin in cricket bowling

This study sought to identify kinematic differences in finger-spin bowling actions required to generate variations in ball speed and spin between different playing groups. A 12-camera Vicon system recorded the off-spin bowling actions of six elite and 13 high-performance spin bowlers, and the “doosra” actions of four elite and two high-performance players. Forearm abduction and fixed elbow flexion in the bowling arm were higher for the elite players compared with the high-performance players. The elite bowlers when compared with the high-performance players delivered the off-break at a statistically significant higher velocity (75.1 and 67.1 km/hr respectively) and with a higher level of spin (26.7 and 22.2 rev/s respectively). Large effect sizes were seen between ball rotation, pelvic and shoulder alignment rotations in the transverse plane. Elbow extension was larger for elite bowlers over the period upper arm horizontal to ball release. Compared to the off-break, larger ranges of shoulder horizontal rotation, elbow and wrist extension were evident for the “doosra”. Furthermore, the “doosra” was bowled with a significantly longer stride length and lower ball release height. Although not significantly different, moderate to high effect size differences were recorded for pelvis rotation, elbow extension and elbow rotation ranges of motion.