Effect of gender on trunk and pelvis control during lateral movements with perturbed landing

In lateral reactive movements, core stability may influence knee and hip joint kinematics and kinetics. Insufficient core stabilisation is discussed as a major risk factor for anterior cruciate ligament (ACL) injuries. Due to the higher probability of ACL injuries in women, this study concentrates on how gender influences trunk, pelvis and leg kinematics during lateral reactive jumps (LRJs). Perturbations were investigated in 12 men and 12 women performing LRJs under three different landing conditions: a movable landing platform was programmed to slide, resist or counteract upon landing. Potential group effects on three-dimensional trunk, pelvic, hip and knee kinematics were analysed for initial contact (IC) and the time of peak pelvic medial tilt (PPT). Regardless of landing conditions, the joint excursions in the entire lower limb joints were gender-specific. Women exhibited higher trunk left axial rotation at PPT (women: 4.0 ± 7.5°, men: ?3.1 ± 8.2°; p = 0.011) and higher hip external rotation at both IC and PPT (p < 0.01). But women demonstrated higher knee abduction compared to men. Men demonstrated more medial pelvic tilt at IC and especially PPT (men: –5.8 ± 4.9°, women: 0.3 ± 6.3°; p = 0.015). Strategies for maintaining trunk, pelvis and lower limb alignment during lateral reactive movements were gender-specific; the trunk and hip rotations displayed by the women were associated with the higher knee abduction amplitudes and therefore might reflect a movement strategy which is associated with higher injury risk. However, training interventions are needed to fully understand how gender-specific core stability strategies are related to performance and knee injury.     

Geography and the Methodological Ballpark: Putting Place into Sports History

This short reflection highlights five aspects of geographical methodological practice which together capture a flavour of how place is being researched, and which offer interesting challenges for historians of sport. A willingness to innovate, to rethink mapping, to enact methods on the move, to deal with big and crowd-sourced data and to adopt playful, positioned approaches are flagged here. Historians of sport can usefully place their research and learn from our diverse geographical experience!     

Inter-joint coordination between hips and trunk during downswings: Effects on the clubhead speed

Understanding of the inter-joint coordination between rotational movement of each hip and trunk in golf would provide basic knowledge regarding how the neuromuscular system organises the related joints to perform a successful swing motion. In this study, we evaluated the inter-joint coordination characteristics between rotational movement of the hips and trunk during golf downswings. Twenty-one right-handed male professional golfers were recruited for this study. Infrared cameras were installed to capture the swing motion. The axial rotation angle, angular velocity and inter-joint coordination were calculated by the Euler angle, numerical difference method and continuous relative phase, respectively. A more typical inter-joint coordination demonstrated in the leading hip/trunk than trailing hip/trunk. Three coordination characteristics of the leading hip/trunk reported a significant relationship with clubhead speed at impact (r < ?0.5) in male professional golfers. The increased rotation difference between the leading hip and trunk in the overall downswing phase as well as the faster rotation of the leading hip compared to that of the trunk in the early downswing play important roles in increasing clubhead speed. These novel inter-joint coordination strategies have the great potential to use a biomechanical guideline to improve the golf swing performance of unskilled golfers.     

Effect of short-term application of kinesio tape on the flexion-relaxation phenomenon,trunk postural control and trunk repositioning in healthy females

This study was designed to investigate the potential effects of kinesio tape on the flexion-relaxation phenomenon, trunk postural control and trunk position sense when applied for a short period (30 min) to the low back of healthy female participants. Twenty-four participants were assigned to one of two groups: kinesio tape applied in either the recommended stretched or non-stretched (control) manner over the low back. Tests were performed at three time points (pre-tape, with tape, post-tape) to assess low-back muscle flexion-relaxation, position sense during active trunk repositioning and trunk postural control during seated balance. Results demonstrated that wearing kinesio tape did not affect the angle at which the erector spinae muscles became silent during trunk flexion (flexion-relaxation). Trunk repositioning error increased when wearing kinesio tape in both the stretched and non-stretched manner, and this increased error persisted after the tape was removed. Seated balance control improved when wearing kinesio tape in both the stretched and non-stretched manner, and these improvements persisted after the tape was removed. In conclusion, these findings do not support the general suggestions that short-term use of kinesio tape on the low-back region alter low-back muscle activation and enhance tasks related to proprioception, at least under these taping conditions in a group of healthy females.     

推铅球技术的演变暨旋转式推铅球技术的要点和难点

推铅球运动．经历了几百年的发展过程。近年来．在世界田径赛场上，运用背向滑步技术和旋转式技术的运动员均创造了优异的成绩。而在我国国内铅球比赛中仍然是背向滑步技术一枝独秀。稀有使用旋转式技术的运动员。在体育院校田径教学中，旋转式推铅球技术也基本是个“空白点”。为了对旋转式技术做进一步了解，丰富体育院校田径教学内容，本运用献资料法、数理统计法、对比分析法对旋转式推铅球技术要点和难点在理论上进行分析探讨。结果表明：(1)旋转式技术比较符合投掷的原理，与背向滑步技术相比具有一定的先进性；(2)旋转式技术以其加速路径比较长，预先速度大。动作自然连贯等技术特征比较适合中国铅球运动员协调性好、爆发力强、速度快等特点。     

推铅球运动项目发展的回顾与展望

采用献资料法对国内外推铅球项目的发展进行了全面简要的回顾，介绍了目前推铅球训练理论研究的热点和前沿，总结了世界高水平铅球运动员训练的特点，揭示了推铅球技术的发展趋势。     

Kinematic constraints associated with the acquisition of overarm throwing part I: step and trunk actions

The purposes of this study were to: (a) examine differences within specific kinematic variables and ball velocity associated with developmental component levels of step and trunk action (Roberton & Halverson, 1984), and (b) if the differences in kinematic variables were significantly associated with the differences in component levels, determine potential kinematic constraints associated with skilled throwing acquisition. Results indicated stride length (69.3 %) and time from stride foot contact to ball release (39. 7%) provided substantial contributions to ball velocity (p < .001). All trunk kinematic measures increased significantly with increasing component levels (p < .001). Results suggest that trunk linear and rotational velocities, degree of trunk tilt, time from stride foot contact to ball release, and ball velocity represented potential control parameters and, therefore, constraints on overarm throwing acquisition.     

Acceleration patterns in the lower and upper trunk during running

Abstract

The purpose of the present study was to relate 3D acceleration patterns of the lower and upper trunk during running to running gait cycle, assess the validity of stride duration estimated from acceleration patterns, investigate speed-dependent changes in acceleration, and examine the test–retest reliability of these parameters. Thirteen healthy young men performed two running trials each on a treadmill and on land at three speeds (slow, preferred, and fast). The 3D accelerations were measured at the L3 spinous process (lower trunk) and the ensiform process (upper trunk) and synchronised with digital video data. The amplitude and root mean square of acceleration and stride duration were calculated and then analysed by three-way analysis of variance to test effects of running conditions, device location, and running speed. Bland-Altman analysis was used to evaluate the test–retest reliability. Marked changes in acceleration were observed in relation to foot strike during running. Stride durations calculated from the vertical accelerations were nearly equal to those estimated from video data. There were significant speed effects on all parameters, and the low test–retest reliability was confirmed in the anterior–posterior acceleration during treadmill running and the anterior–posterior acceleration at slow speed during treadmill and overground running.     

The effects of conscious processing on golf putting proficiency and kinematics

Abstract

Researchers have suggested that skill performance deteriorates when people try to exert conscious control over automatic actions. Unfortunately, little is known about the effects of different types of conscious processing on skilled performance by expert athletes. We conducted two experiments to address this issue. Experiment 1 investigated the influence of a specific form of conscious control (making technical adjustments to a stroke) on the putting skills of expert golfers. The expert golfers maintained putting proficiency (i.e. number of putts holed) when making technical adjustments. However, this form of conscious processing altered the timing and consistency of golfers' putting strokes. Experiment 2 compared the influence of technical adjustments and conscious monitoring (paying attention to the execution of the stroke) on expert golfers' putting skills. Technical adjustments had no disruptive influence on expert golfers' putting proficiency but did reduce the consistency of their strokes. However, conscious monitoring was found to impair putting proficiency. The implications of the work for theory and future work are discussed.     

推铅球最佳成绩和铅球最佳投出角度问题新探

本文通过分析铅球抛体的运动轨迹，得出推铅球的最佳成绩公式及新的铅球最佳投出角度公式，抽样检验，本文给出的两个公式能够准确地描述出高、中、低各种水平铅球运动员最佳投出角度和最好的运动成绩。     

Enhancing motor learning through dyad practice: contributions of observation and dialogue

It has been shown that practice in dyads, as compared to individual practice, can enhance motor learning and increase the efficiency of practice (as two participants can be trained at the same time; Shea, Wulf, & Whitacre, 1999). The dyad practice protocol used by Shea et al. included both observation and dialogue between partners. Thus, it was not clear whether the learning benefits of dyad practice were due to observation, dialogue, or both. The present study examined the individual and interactive effects of observation and dialogue. The task used was speed cup stacking. Participants practiced under one of four conditions: observation/dialogue, observation/no dialogue, no observation/dialogue, and no observation/no dialogue. The two conditions that included observational practice were more effective (i.e., produced faster movement times) than the two conditions without it, both during practice and on a retention test performed under individual performance conditions. This suggests that the learning advantages of dyad practice are primarily due to the opportunity to observe another learner.     

从娱乐与健康的视角提出健美操课程设置应趋向多元化

就目前普通高等院校健美操选修课的教材设置情况,提出课堂内容应赶上时代步法,将时下流行并风靡全国的街舞、有氧搏击、拉丁健美操、爵士舞、瑜珈等深受学生喜爱并亟需了解的内容列入教学大纲,以满足广大学生的求知和娱乐欲望.     

关于投掷最后用力中用力顺序的探讨

我国投掷界对最后用力阶段的用力顺序看法比较一致,认为用力的顺序是自下而上,即腿一髋一躯干(腰、胸)一臂一手。对此,我们有不同的看法,认为正确的用力顺序是髋先发力,然后再向上向下同时发展。在髋动之初,腿的作用仅是一种被动的支撑,其主动用力应在髋动之后。不同认识的用力顺序与最后用力阶段的划分有关,单支撑和双支撑的最后用力阶段分别是不同认识的缘由。双支撑的最后用力是正确用力顺序的基础。用力顺序中的“用力”是一种人为的用力过程,而不是被动过程,是人的主动参与而不是被动接受。从而排除了腿的先动,否定了自下而上的用力顺序。在双支撑状态下的最后用力中强调髋的先动和加强髋周围肌群的力量将有助于投掷运动成绩的提高。     

The movement of the trunk and breast during front crawl and breaststroke swimming

Breast displacement has been investigated in various activities to inform bra design, with the goal of minimising movement; however, breast motion during swimming has yet to be considered. The aim was to investigate trunk and breast kinematics whilst wearing varying levels of breast support during two swimming strokes. Six larger-breasted females swam front crawl and breaststroke (in a swimming flume), in three breast support conditions while three video cameras recorded the motion of the trunk and right breast. Trunk and relative breast kinematics were calculated. Greater breast displacement occurred mediolaterally in the swimsuit condition (7.8, s = 1.5 cm) during front crawl and superioinferiorly in the bare-breasted condition (3.7, s = 1.6 cm) during breaststroke, with the sports bra significantly reducing breast displacements. During front crawl, the greatest trunk roll occurred in the sports bra condition (43.1, s = 8.3°) and during breaststroke greater trunk extension occurred in the swimsuit condition (55.4, s = 5.0°); however, no differences were found in trunk kinematics between the three breast support conditions. Results suggest that the swimsuit was ineffective as a means of additional support for larger-breasted women during swimming; incorporating design features of sports bras into swimsuits may improve the breast support provided.     

The effects of conscious processing on golf putting proficiency and kinematics

Researchers have suggested that skill performance deteriorates when people try to exert conscious control over automatic actions. Unfortunately, little is known about the effects of different types of conscious processing on skilled performance by expert athletes. We conducted two experiments to address this issue. Experiment 1 investigated the influence of a specific form of conscious control (making technical adjustments to a stroke) on the putting skills of expert golfers. The expert golfers maintained putting proficiency (i.e. number of putts holed) when making technical adjustments. However, this form of conscious processing altered the timing and consistency of golfers' putting strokes. Experiment 2 compared the influence of technical adjustments and conscious monitoring (paying attention to the execution of the stroke) on expert golfers' putting skills. Technical adjustments had no disruptive influence on expert golfers' putting proficiency but did reduce the consistency of their strokes. However, conscious monitoring was found to impair putting proficiency. The implications of the work for theory and future work are discussed.     

铅球投掷最佳出手角度推断的假设检验

铅球投掷远度完全由出手参数所决定。假定出手速度不变，推算出的铅球最佳出手角度为４２°的结论是值得怀疑的。笔者采用统计学的假设检验方法对此立论加以证明，认为优秀运动员的理想出手角度为３７°～３９°     

Three-dimensional trunk kinematics in golf: between-club differences and relationships to clubhead speed

The aims of this study were (i) to determine whether significant three-dimensional (3D) trunk kinematic differences existed between a driver and a five-iron during a golf swing; and (ii) to determine the anthropometric, physiological, and trunk kinematic variables associated with clubhead speed. Trunk range of motion and golf swing kinematic data were collected from 15 low-handicap male golfers (handicap = 2.5 ± 1.9). Data were collected using a 10-camera motion capture system operating at 250 Hz. Data on clubhead speed and ball velocity were collected using a real-time launch monitor. Paired t-tests revealed nine significant (p ≤ 0.0019) between-club differences for golf swing kinematics, namely trunk and lower trunk flexion/extension and lower trunk axial rotation. Multiple regression analyses explained 33.7–66.7% of the variance in clubhead speed for the driver and five-iron, respectively, with both trunk and lower trunk variables showing associations with clubhead speed. Future studies should consider the role of the upper limbs and modifiable features of the golf club in developing clubhead speed for the driver in particular.     

赔款摊入田赋的物证

鸦片战争后，帝国主义国家加紧在中国扩张势力范围，妄图瓜分中国，激起中国人民的愤怒和反抗，爆发了义和团反帝爱国运动，西方列强遂组成联合侵略军即所谓“八国联军”，大举进犯天津，北京及我国北方地区，犯下滔天罪行。清政府软弱无能，     

推铅球技术发展趋势

我国女子铅球曾经在世界辉煌一时，但近些年来却出现了严重的滑坡，因而我们有必要进一步认识推铅球技术的发展趋势，从而提高我们训练的科学化水准。本文就推铅球的发展趋势从６个方面进行了分析，期望对提高推铅球水平有所帮助。