Postural tremor and control of the upper limb in air pistol shooters

A postural tremor appears whenever someone attempts to maintain a steady position against gravity. We examined the postural tremor that occurred while air pistol shooters were taking aim so as to compare the coordinative control of the shooters and to identify the features critical to successful shooting. Ten elite and ten pre-elite athletes participated in pistol shooting at 10 m, and the postural tremors in the pistol and upper limb were recorded with lightweight accelerometers. Exploratory analysis showed that the elite shooters had smaller tremor amplitudes than the pre-elite shooters in the pistol and distal arm segments. Compared with the pre-elite shooters, the elite shooters had a smaller tremor amplitude in the lateral direction relative to that in the vertical direction, together with weaker tremor coupling in the lateral direction and stronger vertical coupling of the pistol-hand complex. The resulting shot performance was inversely related to the amplitude of the tremor and to the 8-12 Hz spectral peak of the lateral tremor in the pistol-hand complex. We conclude that the postural tremors of air pistol shooters are associated with the skill of the shooters, and that the elite shooters could optimize the control of the pistol-hand complex, which strongly determined success in shooting.     

Effects of stance width on performance and postural stability in national-standard pistol shooters

Abstract

The aim of the present study was to determine whether changing stance width would result in a corresponding change in postural and/or pistol stability. Twelve national-standard male air pistol shooters performed 10 shots each at five stance widths (30 cm, 45 cm, 60 cm, 75 cm, and 90 cm). Postural stability was determined by measuring centre-of-pressure changes with a dual force-platform system. Shooting mechanics measures were determined by a NOPTEL ST-2000 optoelectronic training system. Medial-lateral centre-of-pressure excursion (F _4,44 = 7.17, P < 0.001, effect size = 0.99) and speed (F _4,44 = 77.03, P < 0.001, effect size = 3.88) were reduced as stance width decreased. Centre of gravity fine (the percentage of time held within an area the size of the ten-ring) improved during narrower stance widths (F _4,32 = 12.49, P < 0.001, effect size = 0.71). Our findings suggest that stance width affects postural and pistol stability in national-standard air pistol athletes. Moreover, the current method of suggesting a wider stance to improve shooting performance should be reconsidered and perhaps air-pistol shooters should use a 30-cm stance width to improve postural stability and shooting performance.     

优秀男子手枪运动员上肢关节屈伸肌群等速肌力测试研究

通过录像观察法、实验测试法,利用德国Isomed 2000等速力量测试系统对男子速射和男子慢射运动员右侧肩关节、肘关节、腕关节依次进行角速度为60°/s等速向心肌肉力量测试,选取屈肌肌群、伸肌肌群的相对峰力矩和相对峰值功率为指标,对手枪男子速射和慢射项目运动员的上肢肌肉力量进行了研究,比较分析了男子速射和男子慢射肩、肘、腕关节屈伸肌群的肌力特征。发现肘关节伸肌肌群、腕关节屈肌肌群分别为速射和慢射影响最大的关节肌群。     

优秀气手枪射击运动员临赛前脑电图变化的特征研究

目的:探讨我国优秀气手枪射击运动员赛前一天和临赛前脑电图变化的特征.方法:应用便携式无需屏蔽的脑电图测试系统,对参加好运北京气手枪射击比赛的我国优秀运动员的赛前一天和临赛前脑电图进行测试分析,比较安静状态和表象状态的变化.结果:赛前一天表象和安静状态相比,整个脑区α波能量百分比降低,β波能量百分比上升;临赛前比较该变化的趋势不明显;赛前一天的平均唤醒水平为17.91%±12.67%,临赛前平均为12.99%±11.65%(P＜0.01);赛前一天的疲劳参数表象状态较安静状态低(P＜0.01),应激参数表象状态高于安静状态(P＜0.05);临赛前的疲劳参数的表象和安静状态相比无差异(P＞0.05),应激参数表象状态小于安静状态(P＜0.01).结论:优秀气手枪射击运动员临赛前大脑平均唤醒水平低于赛前一天,大脑左右半球的协同能力提高,脑电图能在一定程度上反映赛前运动员的紧张度和疲劳度.     

Biomechanical analysis of the change in pistol shooting format in modern pentathlon

Abstract

Despite the importance of the Combined Event to the modern pentathlon competition, little is known about performance in the event. This study aimed to (i) identify the key variables affecting Combined Event shooting performance, and the extent to which these corresponded with those identified for precision shooting and (ii) investigate the impact of changing shooting format, and whether more successful precision shooters were also more successful in the Combined Event. Seven modern pentathletes and three pistol shooters completed precision and Combined Event trials. An opto-electronic shooting system recorded score and pistol movements, whilst force platforms recorded centre of pressure movements 1 s prior to every shot. Intra-individual analysis revealed that the extent of associations between variables was participant-specific, highlighting the need for individual analysis of performance. No participants displayed matching associations between variables for precision and Combined Event shooting, emphasising the difference between performances in the two events. Both groups experienced significantly reduced scores, and increased pistol and body movements for Combined Event shooting (P < 0.05). Despite the pistol shooters’ greater precision shooting ability, no significant differences were evident between the groups’ Combined Event performances (P > 0.05). This implies that experience in one event does not guarantee success in the other, indicating the importance of event specific training.     

探讨快打风格对气手枪项目的作用

射击快打是指在较短时间内快速射击,完成比赛的一种射击风格。随着训练水平提高和比赛规则的改变,加大了比赛难度。因此,快打在训练比赛特别是决赛中应用的优势日渐突出。运动员能否练成稳定的快打风格,适应电子靶训练,不仅是现在射击赛事的需要,也是手枪慢射项目运动员在气手枪训练方面一直在不断探究的方向。本文通过运动员训练数据分析对比,查阅文献,结合教学实际经验,提出快打风格能促进气手枪训练水平提高与比赛发挥这一观点。     

Skill level changes the coordination and variability of standing posture and movement in a pistol-aiming task

The study investigated the coordination and variability of posture and pistol motion for skilled pistol shooters and novices in a pistol-aiming task. The participants stood on a force platform and held a pistol with the preferred arm to aim for accuracy to a target on 30 s trials. The results revealed that the amount of the centre of pressure (COP) and pistol motion was lower for the expert than novice group. The time–varying structure of COP as indexed by multiscale entropy (MSE) and detrended fluctuation analysis (DFA) was also lower for the expert than the novice group. The relative phase between the COP in the anterior–posterior (AP) and pistol in the AP and between the COP in the medial–lateral (ML) and pistol in AP was close to inphase for the both groups. However, for the novice group the coordination patterns of posture and pistol motion were more variable with the pistol motion leading the posture motion while it was lagging in the skilled group. The findings show different qualitative and quantitative dynamics in pistol-aiming as a function of skill level with postural control foundational to supporting the reduced dispersion and complexity of the skilled arm-pistol motion.     

Postural stability,clicker reaction time and bow draw force predict performance in elite recurve archery

Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age?=?24.7?±?7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers.     

The relationship between multiscale dynamics in tremulous motion of upper limb when aiming and aiming performance in different physical load conditions

ABSTRACT

The dynamics of tremulous motion in the upper limb is complex. We aimed to explore the relationship between the complexity of upper limb tremor when aiming and aiming performance and the influences of physical load on the two outcomes. Fifteen modern pentathlon athletes were recruited and completed two 1000-m treadmill running and three 60-s standard aiming task trials: one at baseline and each of the other two immediately after each running. The time series of light spot trace on the target was measured using a high-speed camera. The complexity of this time series was quantified using multiscale entropy. The effective aiming rate was used to assess the aiming performance. We observed that participants with lower tremor complexity had lower effective aiming rate across three physical load conditions (r² > 0.38, p < 0.01). Physical load decreased both tremor complexity (F = 4.8, p = 0.01) and effective aiming rate (F = 13.5, p < 0.0001), but no difference was observed after 1000-m running compared to that after 2000-m running. The per cent change of tremor complexity associated with the change of effective aiming rate (r² = 0.55, p < 0.0001). This pilot study demonstrates that multiscale complexity of tremulous motion in the upper limb when aiming may serve as a novel marker to assess the physiologic system functionality when aiming.     

浅析体育教师体态语言美在教学中的作用

依据体态语言学原理 ,探析了体态语言美的内涵、价值和体育教师体态语言的美学修养、审美教育 ,以及由此对促进学生身心健康和谐发展的重要意义。     

60例颈椎病患者的姿势疗法及运动疗法

60例颈椎病患者进行治疗。采用姿势的调整,并辅以颈椎系列操,的锻炼对通过实践及部分随访发现疗法和运动疗法不仅治疗效果十分显著,而且对于巩固疗效,防止复发也十分有效。     

视觉和前庭功能对自由式滑雪空中技巧运动员姿势控制能力的影响

目的:探讨视觉、前庭功能对自由式滑雪空中技巧运动员姿势控制能力的影响。方法:利用多功能旋转椅和芬兰Metitur平衡分析系统,对18名(男、女各9名)运动员进行姿势控制的抗干扰测试。选取人体压力中心的侧方稳定性Vx、前后方向稳定性Vy和多方稳定性R为测试指标。按性别(男、女性)、站立方式(左腿和右腿站立)和感觉条件(6种)分为3个因素,采用3因素(2×2×6)重复测量方差分析检验不同因素对姿势控制能力差异性的影响。结果:1)各因素的主效应均存在显著性差异(P<0.05),站立方式×感觉条件的交互作用在Vy指标上具有显著性差异(P<0.05);2)各种感觉条件均造成姿势控制能力显著性降低(P<0.01),降低程度为:闭眼+抬头>睁眼+右转>睁眼+左转>闭眼>睁眼+抬头>睁眼;3)侧方稳定性Vx干扰显著性>前后方稳定性Vy(P<0.01);4)向右旋转干扰显著性>向左旋转(P<0.01);抬头条件下干扰男子显著性>女子(P<0.01);5)双重感觉干扰显著性>单一感觉干扰(P<0.01)。结论:前庭旋转的干扰严重降低运动员的姿势控制能力,该项目运动员在前庭旋转的干扰时存在特异性。     

运动中常见的上肢外周神经损伤

采用文献资料法，就常见运动的上肢动作与神经损伤的关系，各种常见上肢外周神经损伤的症状以及诊断，治疗的要点进行了综合分析。     

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.     

Kinetics of the upper limb during table tennis topspin forehands in advanced and intermediate players

The purpose of this study was to determine the significance of mechanical energy generation and transfer in the upper limb in generating the racket speed during table tennis topspin forehands. Nine advanced and eight intermediate table tennis players performed the forehand stroke at maximum effort against light and heavy backspin balls. Five high-speed video cameras operating at 200 fps were used to record the motions of the upper body of the players. The joint forces and torques of the racket arm were determined with inverse dynamics, and the amount of mechanical energy generated and transferred in the arm was determined. The shoulder internal rotation torque exerted by advanced players was significantly larger than that exerted by the intermediate players. Owing to a larger shoulder internal rotation torque, the advanced players transferred mechanical energy from the trunk of the body to the upper arm at a higher rate than the intermediate players could. Regression of the racket speed at ball impact on the energy transfer to the upper arm suggests that increase in the energy transfer may be an important factor for enabling intermediate players to generate a higher racket speed at impact in topspin forehands.     

铅球运动员惠振豹身体素质的灰色关联分析及模式训练研究

运用文献资料法和数理统计分析方法，对我国男子铅球运动员惠振豹各项素质进行了综合分析，找出了影响运动成绩的主要因素，建立了惠振豹的专项成绩的身体素质训练模型，为教练员的训练提供参考依据。     

试析我国女子铅球项目发展的主要特征及存在的主要问题

本文从训练学的角度,通过查阅大量的文献资料和调查研究,探讨了我国女子铅球形成优势的发展时期。其优势的主要特征是：高水平后备人才梯队的雄厚基础;以奥运会、世界田径锦标赛和全运会为训练周期的训练节奏;以速度为核心的投掷技术风格。另外研究发现了我国女子铅球项目高水平年轻后备力量脱节和优秀运动员年龄老化的问题。     

A biomechanical comparison of the topspin and backspin forehand approach shots in tennis

Three‐dimensional (3‐D) high‐speed cinematographic techniques were used to record topspin and backspin forehand approach shots hit down‐the‐line by high‐performance players. The direct linear transformation (DLT) technique was used in the 3‐D space reconstruction from 2‐D images recorded via laterally placed phase‐locked cameras operating at 200 Hz. A Mann‐Whitney U‐test was calculated for the different aspects of the topspin and backspin shots to test for significance (P<0.05).

A significant difference was recorded between topspin and backspin shots in the angle of the racket at the completion of the backswing. The racket was taken 0.48 rad past a line drawn perpendicular to the back fence for topspin trials, but only rotated 0.86 rad from a line parallel to the net in the backspin shot. Maximum racket velocities occurred prior to impact and were significantly higher in topspin (26.5 m s‐¹) compared to backspin (16.6 m s^‐1) trials. This resulted in the topspin trials recording a significantly higher ball velocity compared to backspin trials (27.6 m s^‐1 vs 21.7 m s^‐1). Pre‐impact racket trajectories revealed that in topspin shots the racket moved on an upward path of 0.48 rad while in backspin shots it moved down at an angle of 0.34 rad. In the topspin trials impact occurred significantly further forward of the front foot than in backspin shots (0.26 m vs 0.05 m) while the angle of the racket was the same for both strokes (0.14 rad behind a line parallel to the net). The mean angle of the racket‐face at impact was inclined backwards by 0.11 rad for backspin strokes and rotated forward by 0.13 rad for topspin strokes. Angles of incidence and reflection of the impact between the ball and the court showed that backspin trials had larger angles of incidence and reflection than topspin strokes.     

我国女子铅球一级运动员专项身体素质训练水平与运动成绩分析

通过收集我国27名女子铅球一级运动员65次运动成绩以及相应的专项身体素质指标测验结果,得出影响我国女子铅球一级运动员成绩的专项身体素质的主要因子为:最大力量因素因子、专门投掷训练因素因子、专项速度力量因素因子.并在此基础上,研究得出影响我国女子铅球一级运动员成绩的专项身体素质指标依次是:后抛4kg铅球、30 m站立式起跑、立定跳远和卧推,并给出相应回归方程.依据统计学正态分布原理,运用相应的计算公式,制定出专项身体素质综合发展水平、专项身体素质总体发展均衡程度以及专项身体素质综合发展水平与运动成绩适应程度的3种评定标准.     

Effects of fixed vs. self-suggested rest between sets in upper and lower body exercises performance

In its last position stand about strength training, the American College of Sports Medicine recommends a rest interval (RI) between sets ranging between 1 and 3?min, varying in accordance with the objective. However, there is no consensus regarding the optimal recovery between sets, and most studies have investigated fixed intervals. Therefore, the aim of this study was to analyse the effects of fixed versus self-suggested RI between sets in lower and upper body exercises performance. Twenty-seven healthy subjects (26?±?1.5; 75?±?15?kg; 175?±?12?cm) were randomly assigned into two groups: G1: lower body exercises and G2: upper body exercises. Squat and leg press 1 repetition maximum (1RM) were tested for the G1 and bench press and biceps curl 1RM for G2. After the 1RM tests, both groups performed three sets to concentric failure with 75% of 1RM in combination with different RIs (2?min or self-suggested) on separate days and the exercises performance was evaluated by the number of repetitions. The results demonstrated no significant differences in the number of repetitions between 2?min and self-suggested RIs that presented similar reductions with the sets progression. It was also shown that the self-suggested RI spent less time recovering than the 2?min RI group on average. This suggests that for individuals with previous experience, the self-suggested RI can be an effective option when using workloads commonly prescribed aiming hypertrophy. Also, the self-suggested RI can reduce the total training session duration, which can be a more time-effective strategy.